JP2013116483A - Joining method of aluminum alloy material and dissimilar metal material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new joining method capable of achieving high reliability, excellent joining performance and small material deformation in joining, in a joining method of an aluminum alloy material and a dissimilar metal material.SOLUTION: The joining method of the aluminum alloy material and the dissimilar metal material is used for joining one joining member being the aluminum alloy material and the other joining member being the dissimilar metal material. In the method, the other joining member is the dissimilar metal material having higher solid phase line temperature than the aluminum alloy, and is joined at a temperature where a ratio of a liquid phase mass generated in the aluminum alloy material to the total mass of the aluminum alloy material is 5 to 35%. The one joining member breaks an oxidized film of the surface of the aluminum alloy material by adjustment of Mg concentration of the aluminum alloy material or use of a flux so as to contrive secure joining.

Description

  The present invention relates to a method for joining dissimilar metals, in which an aluminum alloy material is used as one member to be joined, and a metal other than aluminum and any alloy thereof is used as the other member to be joined.

  Conventionally, various methods have been employed for joining metal members. In Non-Patent Document 1, metal joining methods are roughly classified into material joining methods, chemical joining methods, and mechanical joining methods. Any of the above methods can be applied to the joining using an aluminum alloy material as the material to be joined, but the material joining method is particularly used.

  The chemical bonding method is a bonding method using a so-called adhesive. Unlike the material joining method, there is no need to join at a high temperature, and there is an advantage that the members to be joined themselves are not deformed. Examples of the mechanical joining method include rivets and bolting. This method has an advantage that bonding can be performed relatively easily as compared with material bonding methods and chemical bonding methods, and re-bonding can be easily performed depending on the method. However, the chemical bonding method has a drawback that reliability and thermal conductivity of the bonded portion are inferior to those of the material bonding method because strong bonding such as metal bonding cannot be obtained. In addition, the mechanical joining method has a drawback that the shape of the joining portion is limited and is not suitable for joining requiring airtightness and sealing.

  In contrast to the above two bonding methods, the material bonding method is a method in which the members to be bonded are firmly bonded to each other by metal bonding, and the reliability of the bonded portion can be increased by performing appropriately. Due to this advantage, the material joining method has become the most common joining method for aluminum alloy materials that require joining strength, airtightness, and the like.

  The material joining method can be further classified according to the state of the materials to be joined. Specifically, a welding method that melts and joins at least one of the materials to be joined, a diffusion joining method that does not involve melting of the materials to be joined, a friction joining method, a pressure welding method, and other solid-phase joining methods, and brazing And so on.

  In the welding method, the joint is heated by electricity or flame to be melted and alloyed to form a joint. When the gap between the joints is large or when bonding strength is required, the filler material is simultaneously melted at the time of joining to fill the gap. In this method, since the joining portion melts, reliable joining is performed. On the other hand, since the joined portion is melted and joined, the shape near the joined portion is greatly deformed, and the metal structure is also greatly changed locally to become another structure, which may cause local weakening. In addition, since it is necessary to locally heat only the joint portion, there is a problem that it is difficult to join multiple points at the same time.

  On the other hand, the soldering method and the brazing method, which are liquid phase-solid phase reaction bonding methods, use a solder material or a brazing material having a melting point lower than that of the member to be joined, and heat them by electricity or flame, so that these solder materials Only the brazing filler metal is melted to fill the gaps at the joints, thereby joining. This joining method is advantageous for joining point-like or line-like joints, and solder and brazing filler metal form a shape called fillet at the time of joining and solidification, so that it has extremely high reliability in terms of strength and thermal conductivity. Sex is obtained.

  Further, the soldering method and the brazing method can obtain a strong bond in a short time without melting the base material. In particular, in-furnace brazing methods such as the Nocolok brazing method and the vacuum brazing method use a brazing sheet clad with a brazing material and an aluminum alloy material to be joined. By pressing a brazing sheet, assembling a laminated heat exchanger having a hollow structure, and heating in a furnace, members / parts having many joints and a complicated shape can be efficiently manufactured. Brazing methods that take advantage of these advantages are often applied to the joining of products such as automotive heat exchangers and heat sinks that have many joints and are joined at narrow intervals.

  However, the soldering method and the brazing method also have a shortcoming and the liquid phase flows, so that fine flow paths and the like may be filled with wax. Further, in the joining using the brazing sheet, there is an advantage that the brazing can be easily and uniformly supplied to the joining portion. On the other hand, since the production of the brazing sheet is complicated, cost reduction and improvement in procurement are required. Furthermore, there is a problem that the degree of freedom of processing such as cutting on the joint surface side is impaired.

  As the solid-phase bonding method, a diffusion bonding method, a friction bonding method, and the like are known, and these are bonding methods that do not involve melting of the members to be bonded in principle. In the diffusion bonding method, the base materials are brought into close contact with each other, basically pressed to the extent that the plastic deformation does not occur below the melting point of the base material, and bonding is performed using the diffusion of atoms generated between the joint surfaces. In this joining method, multi-point joining and surface joining can be performed simultaneously without deformation of the members to be joined. Therefore, it is possible to join the members to be joined having a fine shape. However, in order to utilize the diffusion phenomenon, it takes a long time for joining as compared with welding, brazing or the like, and usually it is necessary to hold at a predetermined temperature for about 30 minutes or more. Moreover, since pressurization is required for joining, complication of joining operation and cost increase are inevitable. Furthermore, in the case of an aluminum alloy material, since a stable and strong oxide film exists on the surface and diffusion is inhibited thereby, it is difficult to apply solid phase diffusion bonding. In this regard, when an aluminum alloy material containing about 0.5 to 1.0 mass% of Mg is used for the member to be joined, the oxide film is destroyed by the reducing action of Mg, and it is possible to join relatively easily. However, other aluminum alloy materials require a cleaning process to remove the oxide film on the joint surface, and there are problems such as requiring special processes such as argon ion bombardment, glow discharge, and application of ultrasonic waves.

  The friction stir welding method applied to the aluminum material among the friction welding methods, which are also solid phase bonding methods, can be applied to all aluminum alloy materials. Since there is no melting of the base material, there is an advantage that deformation of the member to be joined due to joining is small. On the other hand, the shape of the joint is limited to a straight line or a gentle curve, and it is difficult to join a complicated shape. In addition, since the joining tool is brought into direct contact with the joining portion, it is difficult to join the fine shapes, and it is also difficult to join multiple points at the same time. In addition, in this joining method, it is inevitable that the mark of the joining pin remains at the joining end portion. Furthermore, since the member to be joined is agitated at the joint, there is also a problem that the joint strength is lowered by exhibiting a structure different from the base material.

  The welding method and the solid phase bonding method are distinguished by the presence or absence of melting of the material to be joined. However, other joining methods in which the entire metal member is in a semi-molten state have also been proposed. Patent Document 1 proposes a joining method using semi-melting of alloy powder. In this joining method, the alloy powder as a member to be joined is in a semi-molten state as a whole, so that its shape deformation is remarkable, and is not suitable for joining members for which shape deformation is to be suppressed. Patent Document 2 proposes a method in which a nonmetallic member is press-fitted into a semi-molten alloy base material to join the nonmetallic member and the alloy base material. However, in this joining method, since the punch is pressed and joined to a predetermined mold, the shape of the product is limited.

  Further, in Patent Document 3, an Mg-type aluminum alloy is used for a slot plate and a substrate constituting a waveguide, and a solid-liquid coexistence region or a solid-liquid coexistence of the aluminum alloy is disclosed. A method of performing diffusion bonding by heating and pressurizing at a temperature in the vicinity of the region has been proposed. In this method, the bonding surface is pressed with a jig using a wedge, and the bonding portion is further pressurized by using the difference in thermal expansion between the jig and the aluminum to perform diffusion bonding. At that time, the bonding conditions are shown such that the liquid phase ratio is 1.7% at the maximum between the slot plate and the substrate which are members. However, when the liquid phase ratio is about 1.7%, the liquid phase produced is too small, and there is a possibility that bonding having sufficient strength may not be performed. Further, in the method proposed in Patent Document 3, when the temperature is further increased so that the ratio of the liquid phase is increased, there is a possibility that a large deformation occurs due to excessive pressure. Furthermore, in this method, only a flat plate-like object can be bonded, and the direction of the bonding surface is limited to the pressing direction.

  In Patent Document 4, both of the members to be joined of two metal alloys are forged at a temperature where the solid phase ratio is in the range of 30% or more and less than 90% (liquid phase ratio is 10% or more and less than 70%). There has been proposed a method of inserting into a forging and joining at the same time as forming. Since this method is a method of forming a composite material by forging a plurality of alloy plates, it was not possible to join them while maintaining the shape before and after joining. Moreover, a hollow part cannot be provided between the materials to be joined, and a non-flat material cannot be joined. Furthermore, a large-scale forging device is required at high temperatures.

JP 2005-30513 A JP 2003-88948 A Japanese Patent Laid-Open No. 10-313214 Japanese Patent No. 4261705

Welding and joining technology data book, p. 57, Welding / Joint Technology Data Book Editorial Committee (2007)

  There are various joining methods by the material joining method of the aluminum alloy material as described above, but generally, a joining method that does not melt the member to be joined or a joining method that locally melts only the vicinity of the joint is adopted. Often. This is because if the members to be joined are melted extensively, the shape is not maintained and a desired shape cannot be obtained. However, in order to reliably perform the bonding at a practical speed, it is necessary to melt the members to be bonded even if they are partially rather than not being melted at all. However, even if it is partial, if the member to be joined is melted, deformation of that part cannot be avoided. Therefore, it is necessary to design and assemble the members in consideration of dimensional changes and strength changes after joining.

  Further, in the solid phase diffusion bonding not involving melting, a large pressure is required. Due to this pressurization, the aluminum alloy may be greatly deformed even if it is not melted. In particular, in the case of an aluminum alloy having a fine shape, it becomes difficult to maintain the shape.

  In view of the problems of the prior art as described above, the present invention provides a method for joining an aluminum alloy material and a dissimilar metal material with good joining properties and almost no deformation due to the flow of materials during joining. The purpose is to provide a highly novel joining method.

  As a result of intensive studies, the present inventors pay attention to the metallographic characteristics of the aluminum alloy that is the member to be joined, and use the liquid phase generated when the aluminum alloy is heated for joining with a dissimilar metal material. A new joining method has been found and the present invention has been completed.

  That is, in the first invention according to the present application, an aluminum alloy material is used as one member to be bonded, and a metal other than aluminum or a metal alloy thereof is used as the other member to be bonded. In the method of joining, the one member to be joined is made of an aluminum alloy whose Mg concentration is regulated to 0.5% by mass or less, and the other member to be joined has a solidus temperature higher than that of the one aluminum alloy. A liquid made of a metal or a metal alloy thereof and formed in the aluminum alloy material with respect to the total mass of the aluminum alloy material as the one member to be joined in a state where the flux is applied between the joining members in a non-oxidizing atmosphere. It is a joining method of an aluminum alloy material and a dissimilar metal material characterized by joining at a temperature at which the mass ratio of the phases is 5% or more and 35% or less.

  In addition, the second invention according to the present application uses an aluminum alloy material as one member to be bonded, a metal other than aluminum or a metal alloy thereof as the other member to be bonded, and the one member to be bonded and the other member to be bonded. The one member to be joined is made of an aluminum alloy containing a Mg concentration of 0.2% by mass or more and 2.0% by mass or less, and the other member to be joined is more solid than the one aluminum alloy. The ratio of the mass of the liquid phase generated in the aluminum alloy to the total mass of the aluminum alloy material that is one of the members to be joined in a vacuum or in a non-oxidizing atmosphere made of a metal having a high phase line temperature or a metal alloy thereof. Is a method of joining an aluminum alloy material and a dissimilar metal material, characterized by joining at a temperature of 5% to 35%.

  Hereinafter, the present invention will be described in detail. 1st, 2nd invention which concerns on this application utilizes the predetermined amount of liquid phase produced | generated at the time of the heating of the aluminum alloy material which is one to-be-joined member for joining with the dissimilar metal material which is the other to-be-joined member. The main composition is common. First, the liquid phase generation mechanism will be described. In the present application, the joining using the liquid phase generated by the aluminum alloy material is referred to as “seeding joining”.

  FIG. 1 schematically shows a phase diagram of an Al—Si alloy, which is a typical binary eutectic alloy. When an aluminum alloy material having a Si concentration of c1 is heated, generation of a liquid phase starts at a temperature T1 near the eutectic temperature (solidus temperature) Te. Below the eutectic temperature Te, as shown in FIG. 2A, crystal precipitates are distributed in the matrix divided by the grain boundaries. Here, when the generation of the liquid phase starts, as shown in FIG. 2B, the crystal grain boundary with a large segregation of the crystal precipitate distribution melts to become a liquid phase. Next, as shown in FIG. 2C, the periphery of the Si crystal precipitate particles and intermetallic compounds, which are the main additive element components dispersed in the matrix of the aluminum alloy, melts into a spherical shape to form a liquid phase. Further, as shown in FIG. 2 (d), this spherical liquid phase generated in the matrix is re-dissolved in the matrix with the passage of time and temperature due to the interfacial energy, and the grain boundaries and the surface are diffused by diffusion in the solid phase. Move to. Next, as shown in FIG. 1, when the temperature rises to T2, the liquid phase amount increases from the state diagram.

  Further, in FIG. 1, when the Si concentration of one aluminum alloy material is c2 smaller than the maximum solid solution limit concentration, the generation of the liquid phase starts near the solidus temperature Ts2. However, unlike the case of c1, as shown in FIG. 3A, the structure immediately before melting may not have crystal precipitates in the matrix. In this case, as shown in FIG. 3 (b), after first melting at the grain boundary to become a liquid phase, the liquid phase starts from a location where the solute element concentration is locally high in the matrix as shown in FIG. 3 (c). Occurs. As shown in FIG. 3D, this spherical liquid phase generated in the matrix is re-dissolved in the matrix with the passage of time and temperature due to the interfacial energy, as in the case of c1, and diffused in the solid phase. To move to the grain boundary or surface. When the temperature rises to T3, the liquid phase amount increases from the state diagram.

  The amount of the liquid phase that oozes out by the mechanism as described above and is supplied to the joined portion is very small compared to brazing, and the shape change in the vicinity of the joined portion hardly occurs after the joining step. In other words, the liquid phase supplied to the joint is just enough to fill the gap between the aluminum alloy material and the dissimilar metal material, and the shape change after joining, such as the bead of the welding method and the fillet in the brazing method, It hardly occurs in the joining method according to the present invention. In spite of this, joining by metal bonding is possible as in the welding method and the brazing method. Therefore, it is necessary to consider the decrease in product design. In the exudation joining of the present invention, since the dimensional change after joining is extremely small, a highly accurate product design is possible.

  Thus, the seepage bonding of the present invention utilizes a liquid phase generated by local melting inside the aluminum alloy material. And it can implement | achieve both joining and shape maintenance by making mass of a liquid phase into a suitable range by adjustment of heating temperature. In addition, the dissimilar metal material which is the other to-be-joined member in this invention needs to be below the solidus temperature at the said heating temperature. When the dissimilar metal material exceeds the solidus temperature, the dissimilar metal material starts to melt, reacts with the aluminum alloy near the joint interface, and the liquid phase generation accelerates rapidly near the joint interface. This is because the shape may not be maintained.

  The basic mechanism of joining common to the first and second inventions according to the present application is as described above. And, it is the difference between the first and second inventions according to the present application, but it is in a technique for destroying the oxide film of the aluminum alloy member which is one member to be joined. It is the presence or absence of adjustment of Mg concentration and use of flux. Details of these methods will be described later, and the features of the first and second inventions according to the present application will be described in more detail.

A. The combination of the bonded members First, the exudation joining of the aluminum alloy material according to the present invention, an aluminum alloy material as one of the workpieces, the dissimilar metal material as the other member to be joined, one of the workpieces and the other The member to be joined is joined. Note that, as described above, in order to enable exudation joining, the dissimilar metal material includes a metal having a solidus temperature higher than that of one aluminum alloy or a metal alloy thereof.

B. Range of mass ratio of liquid phase In the exudation joining of the aluminum alloy material according to the present invention, the ratio of the mass of the liquid phase generated in the aluminum alloy material to the total mass of the aluminum alloy material which is one of the members to be joined (hereinafter referred to as , Described as “liquid phase ratio”) at a temperature of 5% to 35%. If the liquid phase ratio exceeds 35%, the amount of the liquid phase to be generated is too large, and the aluminum alloy material cannot maintain its shape and undergoes large deformation. On the other hand, if the liquid phase ratio is less than 5%, joining becomes difficult. A preferable liquid phase rate is 5 to 30%, and a more preferable liquid phase rate is 10 to 20%.

It is extremely difficult to measure the actual liquid phase rate during heating. Therefore, the liquid phase ratio defined in the present invention is usually based on this principle (level) based on the alloy composition and the maximum temperature achieved using an equilibrium diagram.
rule). In an alloy system whose phase diagram has already been clarified, the liquid phase ratio can be determined using the phase diagram using the phase diagram. On the other hand, for an alloy system whose equilibrium phase diagram is not disclosed, the liquid phase ratio is obtained using equilibrium calculation phase diagram software. The equilibrium calculation phase diagram software incorporates a technique for determining the liquid phase ratio based on the lever principle using the alloy composition and temperature. The equilibrium calculation state diagram software includes Thermo-Calc; manufactured by Thermo-Calc Software AB. Even in an alloy system whose equilibrium phase diagram has been clarified, calculating the liquid phase rate using the equilibrium calculation phase diagram software is the same as the result of calculating the liquid phase rate using this principle from the equilibrium phase diagram. As a result, equilibrium calculation state diagram software may be used for simplification.

C. Method for Destroying Oxide Film A strong oxide film is formed on the surface layer of the aluminum alloy material, which inhibits bonding. Therefore, it is necessary to destroy the oxide film in joining. The first and second inventions according to the present invention both include a method for destroying an oxide film. Next, a specific method for removing the oxide film in each invention will be described. In the following explanation, the destruction of the oxide film of aluminum will be explained. However, the oxide film of aluminum is extremely strong, and compared to aluminum, different metal materials usually reduce the oxide film even if an oxide film is formed.・ Easily destroyed. Therefore, if the oxide film of aluminum is destroyed, the oxide film of dissimilar metal is also destroyed at the same time, and bonding is possible.

C-1. Destruction of oxide film by flux This method is a method employed in the first invention of the present application, in which flux is applied to at least the joint portion in order to destroy the oxide film. The flux is fluoride flux such as KAlF ₄ , K ₂ AlF ₅ , K ₂ AlF ₅ .H ₂ O, K ₃ AlF ₆ , AlF ₃ , KZnF ₃ , K ₂ SiF ₆ used for brazing of aluminum alloys, Cs Cesium flux such as ₃ AlF ₆ , CsAlF ₄ .2H ₂ O, Cs ₂ AlF ₅ .H ₂ O, or chloride flux such as KCl, NaCl, LiCl, ZnCl ₂ is used. These fluxes melt before the liquid phase melts or reaches the joining temperature in the seepage joining, and react with the oxide film to destroy the oxide film.

  Furthermore, in this method, in order to suppress the formation of an oxide film, bonding is performed in a non-oxidizing atmosphere such as nitrogen gas or argon gas. In particular, when a fluoride-based flux is used, bonding is preferably performed in a non-oxidizing gas atmosphere in which the oxygen concentration is suppressed to 250 ppm or less and the dew point is suppressed to -25 ° C. or less.

  In addition, when a fluoride-based flux is used, if the aluminum alloy material of one member to be joined contains Mg in an amount exceeding 0.5 mass%, the flux and Mg react to oxidize the flux. The film breaking action is impaired. Considering this point, the upper limit of the Mg concentration of the aluminum alloy material of one member to be joined is set to 0.5 mass%. In addition, if the Mg content satisfies the condition of 0.5% by mass or less, there is no limitation on the type and content of other elements contained in the aluminum alloy.

C-2. Breakage of oxide film by getter action of Mg This method is employed in the second invention of the present application. In this method, a material in which a predetermined amount of Mg is added to the aluminum alloy material is applied. In this case, the oxide film is broken and bonding can be performed without applying a flux to the bonding portion. At this time, when the aluminum alloy melts and the liquid phase comes out on the surface layer, the oxide film is destroyed by the getter action of Mg that evaporates from the aluminum alloy. In the second invention, the Mg concentration of the aluminum alloy material is 0.2% by mass or more and 2.0% by mass or less. If less than 0.2% by mass, the getter action of Mg cannot be expected. This is because if the content exceeds 0% by mass, a large amount of MgO oxide film is formed in the heating process, and the bondability is significantly reduced.

  The exudation joining method according to the present invention can perform reliable joining while minimizing deformation of the members to be joined by the basic configuration described above. Here, in the present invention, preferable joining can be obtained by appropriately setting the joining time and the stress applied to both the joined members as the joining conditions considering the shape maintenance of the joined members.

D. Joining Time Required for Maintaining Shape In the present invention, the meaning of joining time is the time during which the liquid phase ratio in an aluminum alloy material, which is one member to be joined that produces a liquid phase, is 5% or more. And this joining time is preferably within 3600 seconds. When it is within 3600 seconds, a joined body with little shape change from before joining can be obtained, and when within 1800 seconds, a precise joined body with further less shape change can be obtained. The joining time is preferably 30 seconds or longer. If it is 30 seconds or more, a bonded body reliably bonded can be obtained, and if it is 60 seconds, a bonded body bonded more reliably can be obtained.

E. Stress applied to both members to be bonded at the time of bonding In the bonding according to the present invention, it is not always necessary to apply pressure to the bonding surface as long as both members to be bonded are in contact with each other at the bonding portion. However, in an actual product manufacturing process, stress is often applied to both members to be joined by a jig or the like in order to fix the members to be joined or to reduce the clearance. Further, stress is also generated in the member to be joined by its own weight.

  At this time, the stress which generate | occur | produces in each site | part in each to-be-joined member is calculated | required from a shape and a load. This stress can be calculated using, for example, a structure calculation program. In the present invention, P (kPa) is the maximum stress (maximum stress) among the stresses generated in each part of the bonded member that generates a liquid phase during bonding, and the liquid phase ratio of the aluminum alloy that is the bonded member When V is V, bonding is preferably performed so as to satisfy P ≦ 460-12V. The value shown on the right side of this equation is the critical stress, and if a stress exceeding this is applied to the member to be joined that generates a liquid phase, large deformation occurs in the member to be joined even if the liquid phase ratio is within 35%. There is a fear.

F. Specific examples of the combination of the materials to be joined As described above, the combination of the members to be joined to which the seepage joining of the aluminum alloy material according to the present invention is applied, the aluminum alloy material is one member to be joined, and the dissimilar metal material is used. The other member to be joined is used. Here, a suitable example for each member to be joined will be described below.

F-1. Aluminum alloy material (difference between solidus temperature and liquidus temperature)
The aluminum alloy material that generates the liquid phase as one member to be joined preferably has a difference between the solidus temperature and the liquidus temperature of 10 ° C. or more. When the solidus temperature is exceeded, the generation of the liquid phase begins, but if the difference between the solidus temperature and the liquidus temperature is small, the temperature range in which the solid and the liquid coexist is narrowed, and the amount of the generated liquid phase is reduced. It becomes difficult to control. Therefore, this difference is preferably set to 10 ° C. or more. Specific examples of the binary alloy having a composition satisfying this condition include an Al—Si alloy, an Al—Cu alloy, an Al—Mg alloy, an Al—Zn alloy, an Al—Ni alloy, and the like. It is done.

  As an aluminum alloy material satisfying the above conditions, the eutectic aluminum alloy as described above is advantageous because it has a large solid-liquid coexistence region. However, it is possible to achieve good bonding with other solid solution type, peritectic type, and monotectic type alloys as long as the difference between the solidus temperature and the liquidus temperature is at least 10 ° C. It becomes. In addition, the above binary alloy can contain an additive element other than the main additive element, and the present invention can be applied to a ternary alloy, a quaternary alloy, and a multi-element alloy of more than 5 elements. Applicable. For example, Al-Si-Mg, Al-Si-Cu, Al-Si-Zn, Al-Si-Cu-Mg, and the like can be given.

  The larger the difference between the solidus temperature and the liquidus temperature, the easier it is to control the amount of liquid phase. Therefore, there is no particular upper limit for the difference between the solidus temperature and the liquidus temperature. Moreover, it is more preferable that the temperature range when the liquid phase rate is 5% to 35% is more than 10 ° C, and the aluminum alloy material that generates the liquid phase is when the liquid phase rate is 5 to 35%. More preferably, the temperature range is 20 ° C. or higher.

  In addition, in the joining method of the aluminum alloy material and the dissimilar metal material according to the present invention, the reason why the melting side is made of an aluminum alloy is that when a strong oxide film of the aluminum alloy is broken, a liquid phase is generated from the aluminum alloy side. This is because the destruction of the oxide film becomes easier. In particular, when joining using the getter effect of the Mg element described above, it is necessary for Mg to break through the oxide film from the inside of the liquid phase, and joining becomes difficult unless a liquid phase is generated from the aluminum alloy side.

F-2. Dissimilar metal material As described above, the dissimilar metal material is made of a metal having a solidus temperature higher than that of one aluminum alloy or an alloy thereof in order to enable exudation joining. As the dissimilar metal material, the present invention can be applied to any metal of iron, copper, titanium, nickel, magnesium, or a metal alloy thereof. In the present invention, “metal” refers to a pure metal, which includes a pure metal containing inevitable impurities.

  As described above, the joining method of the aluminum alloy material and the dissimilar metal material according to the present invention performs joining by utilizing a slight liquid phase generated inside the aluminum alloy to be joined. In the present invention, the aluminum alloy material and the dissimilar metal material can be joined by highly reliable metal bonding.

  Further, in the present invention, since the member to be joined itself does not flow greatly due to melting and does not use a solder material, a brazing material, a solubilizing material, or the like, a dimensional change due to joining is small, and a shape change hardly occurs. In particular, even in joining members having fine flow paths, good joining can be performed without clogging the flow paths due to inflow or deformation of the liquid phase.

  Further, simultaneous multipoint joining having the same reliability as the brazing method can be performed without using a brazing sheet, brazing paste, brazing sheet clad with a brazing material, or the like. Thereby, the cost of the material can be reduced without impairing the bonding performance.

  The present invention is similar to the diffusion bonding in that the deformation due to bonding is small and simultaneous multi-point bonding is possible. However, compared to the diffusion bonding, no pressure is required, and the time required for bonding can be shortened. Even if it is joining of the aluminum alloy material which does not contain, there exists an advantage that the special process for the cleaning process of a joint surface is not required.

It is a schematic diagram which shows the phase diagram of an Al-Si alloy as a binary eutectic alloy. It is explanatory drawing which shows the production | generation mechanism of the liquid phase in an aluminum alloy material in the joining method of the aluminum alloy material and dissimilar metal material which concern on this invention. It is explanatory drawing which shows the production | generation mechanism of the liquid phase of an aluminum alloy material in the joining method of the aluminum alloy material and dissimilar metal material which concern on this invention. It is a perspective view which shows the reverse T-shaped joining test piece for evaluating a joining rate. It is the perspective view (a) and side view (b) explaining the sag test for evaluating a deformation rate.

  Below, this invention is demonstrated in detail based on an Example and a comparative example. In the following, a plurality of aluminum alloy materials and dissimilar metal materials were prepared, joined by applying the seepage joining method according to the present invention, and the joining property was evaluated (first embodiment). In addition, a detailed examination was performed on the evaluation of the deformation rate of the aluminum alloy material (second embodiment).

1st Embodiment (Examples 1-37, Comparative Examples 38-59)
Table 1 shows the composition of the aluminum alloy material used as one of the materials to be joined. After preparing the alloy ingot shown in Table 1, a rolled plate having a thickness of 2 mm was obtained by hot rolling and cold rolling. The rolled plate was subjected to a leveler and then annealed at 380 ° C. for 2 hours to obtain a rolled plate sample.

  Table 2 shows the composition of the dissimilar metal material used as the other member to be joined. After preparing the alloy ingot shown in Table 2, a rolled plate having a thickness of 3 mm was obtained by hot rolling and cold rolling. In addition, about B12, after rolling the material of Table 1, the nickel plating (thickness 5 micrometers) was given to the surface.

Using the aluminum alloy material and the rolled metal sample of different metal materials prepared as described above, a joining test was performed to evaluate the joining rate and the deformation rate. In this joining test, first, two plates having a width of 20 mm and a length of 50 mm are cut out from the rolled plate sample, each end face is smoothed by a mill, an aluminum alloy material is used as an upper plate, and a dissimilar metal material is used as a lower plate. As a result, an inverted T-shaped joining test piece shown in FIG. 4 was produced. Table 3 shows combinations of the upper and lower plates of each test piece. The bonding test piece was applied with a potassium fluoride, cesium fluoride, or chloride flux, or no flux. Tables 6 to 8 show the presence and type of flux application. In these tables, “F” is potassium fluoride-based non-corrosive flux (KAlF ₄ ), “Cs” is cesium fluoride-based non-corrosive flux (CsAlF ₄ ), and “Cl” is chloride-based. Flux (NaF: 7%, NaCl: 25%, ZnCl ₂ : 8%, LiCl: 13%, KCl: 47%), “−” indicates a case where no flux was applied.

Then, the test piece is heated to a predetermined temperature in a nitrogen atmosphere, an argon atmosphere or a vacuum atmosphere and held at that temperature (joining temperature shown in Table 3) for a predetermined time, and then naturally in a furnace. Cooled down. The nitrogen atmosphere and the argon atmosphere were controlled at an oxygen concentration of 100 ppm or less and a dew point of −45 ° C. or less. The vacuum atmosphere was controlled at 10 ⁻⁵ torr. In any atmosphere, the heating rate was 10 ° C./min at 520 ° C. or higher. And from the test piece after joining heating, a joining rate, a deformation rate, and comprehensive evaluation were evaluated as follows.

(1) Joining rate evaluation The joining rate was calculated | required as follows. Using an ultrasonic flaw detector, the length of the portion where the joint portion is joined was measured. The total length of the joint part of the inverted T-shaped test piece was set to 50 mm, and the joining rate (%) was calculated by {the length of the part joined at the joint part (mm) / 50 (mm)} × 100. The bonding rate was determined as ◎ when 95% or more, ○ when 90% or more and less than 95%, △ when 25% or more and less than 90%, and × when less than 25%.

(2) Deformation rate evaluation A plate having a width of 10 mm and a length of 30 mm was cut out from the rolled plate sample having the composition shown in Table 1 to obtain a test piece for measuring the deformation rate. As shown in FIG. 5 (a), this test piece was set to a sag test jig with a protruding length of 20 mm (three test pieces are set in the figure). The maximum stress P (N / m ² ) in the cantilever shape as in the sag test was determined from the bending moment M and the section modulus Z as follows.

P = M / Z = (W × I 2/2) / (bh 2/6)
= [(G × ρ × I × b × h / I) × I 2/2] / (bh 2/6)
= 3 × g × ρ × I ² / h
M: Bending moment (N · m)
In the case of a uniformly distributed load of the cantilever W × ^I 2/2
Z: Section modulus (m ³ )
If the cross-sectional shape of a rectangular ^bh 2/6
W: Uniformly distributed load (N / m)
g: Gravity acceleration (m / s ² )
ρ: Aluminum density (kg / m ³ )
I: Projection length (m)
b: Plate width (m)
h: Plate thickness (m)

  The maximum stress P is applied to the base of the protruding portion. The maximum stress P applied to the test piece in this test was 31 kPa as a result of calculation by assigning a numerical value to the above equation. The test piece was heated to a predetermined temperature in the atmosphere shown in Table 3 and held at that temperature (joining temperature shown in each table) for a predetermined time shown in each table, and then naturally cooled in a furnace. The nitrogen atmosphere and the argon atmosphere were controlled at an oxygen concentration of 100 ppm or less and a dew point of −45 ° C. or less. The vacuum atmosphere was controlled at 10-5 torr. In any atmosphere, the heating rate was 10 ° C./min at 520 ° C. or higher.

  The deformation rate was determined from the test piece after heating as follows. As shown in FIG. 5 (b), the amount of droop of the test piece after heating was measured. Using the protrusion length (20 mm), the deformation rate (%) was calculated by {amount of droop (mm) / 20 (mm)} × 100. Deformation rates of 50% or less were evaluated as ◎, over 50% and 70% or less as ◯, over 70% and 80% or less as Δ, and over 80% as x.

(3) Comprehensive judgment From the above results, for each assessment judgment, ◎ is given 5 points, ○ is 3 points, △ is 0 points, × is -5 points, and the total score is 10 points. The overall judgment was made with 6 to 9 points being ◯, 1 to 5 points being Δ, and 0 points or less being x. In the comprehensive judgment, ◎, ○, and △ were accepted, and x was rejected. The results of the joining rate, deformation rate, and comprehensive judgment are shown in Table 3 together with the joining conditions (temperature, equilibrium liquid phase rate calculated values).

  As can be seen from Table 3, in Examples 1 to 37, the liquid phase ratio in the aluminum alloy material at the time of bonding heating was in an appropriate range, so that good bonding was made and the overall judgment was acceptable.

  On the other hand, looking at the comparative examples from the viewpoint of the liquid phase amount, in Comparative Examples 38, 43, 48, 50, and 52, since the liquid phase amount generated in the aluminum alloy material was too low, the bonding rate was low and the overall judgment was not good. Passed. Further, in Comparative Example 39, no liquid phase was generated in the aluminum alloy material, so that the joining was not performed and the comprehensive judgment was rejected. Furthermore, in Comparative Examples 40, 42, 44 to 47, 49, 51, and 53 to 56, since the amount of liquid phase generated in the aluminum alloy material was too large, the deformation rate was high and the comprehensive judgment was rejected.

  In addition, from the relationship between the brazing filler metal composition and the presence / absence of the use of flux, in Comparative Examples 41 and 57, the flux was not applied even though the Mg content of the aluminum alloy material was less than 0.2% by mass, so that bonding was not possible. It became enough, and comprehensive judgment failed. Moreover, in Comparative Example 58, since the flux was applied even though the Mg content of the aluminum alloy material exceeded 0.5% by mass, the joining was insufficient and the comprehensive judgment was rejected. Further, in Comparative Example 59, even when no flux was applied, the Mg content of the aluminum alloy material exceeded 2.0 mass%, so that the bonding was insufficient, and the comprehensive judgment was rejected.

Second Embodiment (Examples 60 to 71, Reference Examples 1 to 3)
Here, a sag test was performed to evaluate the stress P that the bonded member can withstand during heating. In this evaluation, the conditions (alloy and heating conditions) that pass the overall evaluation are selected in the evaluation according to the first embodiment, and only the deformation rate of the aluminum alloy material is evaluated in more detail. As the test piece, the aluminum alloy material shown in Table 1 was selected and used. The test piece had a plate thickness of 1 mm, a width of 15 mm, and a length of 60 mm. The protruding length of this test piece was changed to 20 to 50 mm, and the sag test jig shown in FIG.

  Specifically, the test piece was heated to a predetermined temperature in a nitrogen atmosphere and held at that temperature for 180 seconds, and then naturally cooled in a furnace. The nitrogen atmosphere was controlled at an oxygen concentration of 100 ppm or less and a dew point of −45 ° C. or less. The heating rate was 10 ° C./min at 520 ° C. or higher.

  The deformation rate was determined from the test piece after heating as follows. As shown in FIG. 5 (b), the amount of droop of the test piece after heating was measured. Using each protrusion length, the deformation rate (%) was calculated by {the amount of droop (mm) / the protrusion length (mm)} × 100. A deformation rate of less than 50% was evaluated as ◎, 50% or more and less than 70% as ◯, and 70% or more as x. ◎ and ○ were accepted, and x was rejected. Deformation rate, protrusion length, stress and critical stress are shown in Table 4 together with heating conditions (heating temperature, liquid phase rate, holding time at heating temperature).

  From Table 4, in Examples 60-71, stress P (kPa) was below the critical stress (460-12V) which made V (%) the liquid phase rate. As a result, in all of these examples, the amount of sag was less than 70% with respect to the protruding length, and a good deformation rate was obtained. On the other hand, in Reference Examples 1 to 3, the stress P was larger than the limit stress (460-12V). As a result, the drooping amount was 70% or more with respect to the protruding length, and the deformation rate was large.

  From the above results, it is confirmed that if the stress P applied to the member to be joined is not more than the limit stress (460-12V), the deformation before and after joining the members is suppressed to within 5%, and a highly accurate structure can be manufactured. It was done.

  According to the present invention, it is a highly reliable joining method between an aluminum alloy material and a dissimilar metal material that has good joining properties and hardly undergoes deformation due to joining, and has a great industrial value. According to the present invention, it is possible to efficiently manufacture members / parts having features such as a large number of joints and a complicated shape, which is useful for joining, for example, a heat exchanger or a heat sink.

Claims (5)

In the method of joining the one member to be joined and the other member to be joined, using an aluminum alloy material as one member to be joined, a metal other than aluminum or its metal alloy as the other member to be joined,
The one bonded member is made of an aluminum alloy whose Mg concentration is regulated to 0.5% by mass or less,
The other member to be joined is made of a metal having a higher solidus temperature than the one aluminum alloy or a metal alloy thereof,
In a state where the flux is applied between the joining members in a non-oxidizing atmosphere, the ratio of the mass of the liquid phase generated in the aluminum alloy material to the total mass of the aluminum alloy material which is the one member to be joined is 5%. A joining method of an aluminum alloy material and a dissimilar metal material, characterized by joining at a temperature of 35% or less. In the method of joining the one member to be joined and the other member to be joined, using an aluminum alloy material as one member to be joined, a metal other than aluminum or its metal alloy as the other member to be joined,
The one member to be joined is made of an aluminum alloy containing Mg concentration of 0.2% by mass or more and 2.0% by mass or less,
The other member to be joined is made of a metal having a higher solidus temperature than the one aluminum alloy or a metal alloy thereof,
Bonding in a vacuum or in a non-oxidizing atmosphere at a temperature at which the ratio of the mass of the liquid phase generated in the aluminum alloy to the total mass of the aluminum alloy material as the one member to be bonded is 5% or more and 35% or less A method for joining an aluminum alloy material and a dissimilar metal material.   In the aluminum alloy material which is one member to be joined, the time during which the ratio of the mass of the liquid phase generated in the aluminum alloy material to the total mass of the aluminum alloy material is 5% or more is 30 seconds or more and 3600 seconds or less. The joining method of the aluminum alloy material of Claim 1 or 2, and a dissimilar metal material.   The maximum stress generated in the aluminum alloy material that is one member to be joined is P (kPa), and the ratio of the mass of the liquid phase generated in the aluminum alloy material to the total mass of the aluminum alloy material is V (%). When joining, the joining method of the aluminum alloy material and dissimilar metal material as described in any one of Claims 1-3 which join on the conditions which satisfy | fill P <= 460-12V. The other member to be joined is made of any metal of iron, copper, titanium, nickel, magnesium, or an alloy based on the metal, and is different from the aluminum alloy material according to any one of claims 1 to 4. Metal material joining method.

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