JP6023074B2 - Aluminum member joining method - Google Patents

Description

  The present invention relates to a method for joining aluminum members together, and an aluminum structure joined by the joining method.

  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 these methods is used for joining aluminum members, and specifically, material joining methods such as a welding method, a soldering method, and a brazing method have been used.

  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. Thus, since a junction part melts, reliable joining is made. On the other hand, since the joint portion is melted and joined, the shape in the vicinity of the joint 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. There existed problems, such as an unjoined part remaining and a residual stress producing, and the weight increase by adding a filler material.

  Further, the brazing method has a problem that a shape change occurs due to a flow caused by melting of the brazing material. Even when a brazing material is used in addition to the member to be joined, or when the brazing material is clad and integrated with the joining material, a certain amount of brazing material is required. Even if it exists, there was a problem of filling the gap. Further, when a brazing material is prepared separately, the assembly is troublesome, and the clad material has a problem that the material cost becomes high.

  On the other hand, the seepage bonding shown in Patent Document 1 is a highly reliable new bonding method with good bonding properties and almost no deformation due to the flow of materials during bonding. 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, there is a feature that a dimensional change due to joining is small and hardly changes in shape. 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. Moreover, since strong pressurization between the bonding surfaces is not required unlike diffusion bonding, the bonding is not limited to a flat plate shape, and bonding in which the end portions of the members are abutted is also possible. Since the materials themselves can be joined, the assembly is not complicated as in brazing using a brazing material, and the material cost is not as high as that of a clad material of brazing material.

  As described above, the exudation joining is a joining method that solves the problems of the conventional joining methods, and has many advantages in joining aluminum materials.

International publication WO2011 / 152556

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

  Aluminum materials are highly demanded as structures because of their high specific strength, and if there is a lightweight and high-strength structure, a large industrial effect can be obtained. However, when the above-mentioned squeeze-out joining is used in a joint shape such as a structure, stress concentration tends to occur at a portion where the end portions of the members are butted together.

  The reason is considered as follows. In the case of normal brazing, a fillet is formed that fills the joint with liquid phase brazing and thickens the shape in the vicinity of the joint, and in the case of welding, the filler is added to the vicinity of the joint by melting the joint. A bead for thickening the shape is formed. In these joining methods, stress is dispersed by a fillet or bead that relaxes a sudden change in cross-sectional area between members. On the other hand, in the seepage joining, since a fillet or bead that relaxes the cross-sectional area change between the members is not formed in the joint portion, the sudden cross-sectional area change cannot be mitigated, and stress concentrates on the joint portion. Therefore, there is a demand for a joining method suitable for seepage joining that can improve the joint strength by eliminating the stress concentration at the joint while utilizing the advantage of seepage joining.

  The present invention has been made in view of such technical background. In aluminum structures using exudation bonding, there is no stress concentration in the joint part and it has sufficient strength, and there is no structural change or shape change as in welding or brazing, etc. An object of the present invention is to provide a method for joining aluminum members.

The present invention is a method for joining a first aluminum member and a second aluminum member, wherein at least one of the first and second aluminum members is placed in the aluminum member with respect to its total mass. In the joining method of joining to the other aluminum member at a temperature at which the mass ratio of the liquid phase to be produced is 5% or more and 35% or less,
Bonding width of the bonded portion of the first and second aluminum members, said second aluminum alloy member, than the first and the minimum width of the cross section along the joint surface and parallel to the plane of the second aluminum members Make it bigger
The first and second aluminum members are made of an aluminum material regulated to Mg: 0.5% by mass or less,
The bonding is performed in a non-oxidizing atmosphere with a fluoride-based or chloride-based flux applied to the bonding portion .

The present invention is a method for joining a first aluminum member and a second aluminum member, wherein at least one of the first and second aluminum members is generated in the aluminum member with respect to its total mass. In the joining method of joining with the other aluminum member at a temperature at which the mass ratio of 5% or more and 35% or less,
The joining width of the joining portion of the first and second aluminum members is smaller than the minimum width of the cross section along the plane parallel to the joining surfaces of the first and second aluminum members of the second aluminum alloy member. Make it bigger
The first aluminum member is made of an aluminum material containing Mg: 0.2% by mass or more and 2.0% by mass or less, and the second aluminum member is regulated to have an Mg content of 2.0% by mass or less. Made of aluminum material,
The bonding is performed in a vacuum, in a non-oxidizing atmosphere or in the air, and provides a method for bonding aluminum members.

In the present invention, the joining surfaces of the first and second aluminum members may each be a single plane.

In the present invention, the joining surfaces of the first and second aluminum members may each be composed of a plurality of complementary planes or complementary curved surfaces between the two members.

When the joint surfaces of the first and second aluminum members are each composed of a plurality of planes complementary between the two members, the joint surfaces are formed from two planes or three planes complementary between the two members. Thus, the cross section of the joint perpendicular to the joint surface may be substantially L-shaped or substantially U-shaped.

When the joint surfaces of the first and second aluminum members are each composed of a plurality of planes complementary between the two members, the joint surfaces are composed of a plurality of continuous planes complementary between the two members, The cross section of the joint perpendicular to the joint surface may be serrated, stepped, or uneven.

The joint surfaces of the first and second aluminum members may each be a complementary curved surface between the two members, and the cross section of the joint portion orthogonal to the joint surface may be wavy.

  According to the present invention, it is possible to provide a simple aluminum member joining method that does not require a solution material or a brazing material, and further to provide an aluminum structure having sufficient strength without stress concentration at the joint portion. it can.

  If it explains in full detail about a joining method, it has the following original features of exudation joining. That is, since the member to be joined itself does not flow greatly due to melting and does not use solder material, brazing material, solution material, or the like, the dimensional change due to joining is small and almost no shape change 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, since local structural change does not occur in the vicinity of the joint, strength embrittlement hardly occurs. In addition, simultaneous multipoint joining having the same reliability as that of the brazing method can be performed without using a brazing sheet, brazing paste, brazing sheet clad with brazing material, or the like. Thereby, the cost of the material can be reduced without impairing the bonding performance.

  Similar to the present invention, compared to diffusion bonding, in which there is little deformation due to bonding and simultaneous multipoint bonding is possible, pressurization is not required, the time required for bonding can be shortened, and aluminum alloy materials that do not contain Mg can be bonded. Even if it exists, the special process for the cleaning process of a joint surface is not required.

It is sectional drawing which shows the Example of the joining form in this invention. It is sectional drawing which shows the other Example of the joining form in this invention. It is sectional drawing which shows the other Example of the joining form in this invention. It is a schematic diagram which shows the angle ((theta)) which the centerlines along the longitudinal direction of a 1st aluminum member and a 2nd aluminum member make. It is sectional drawing which shows the Example which changed the joining surface of the joining form in this invention. It is sectional drawing which shows the other Example which changed the joining surface of the joining form in this invention. It is sectional drawing which shows the other Example which changed the joining surface of the joining form in this invention. It is sectional drawing which shows the other Example which changed the joining surface of the joining form in this invention. It is sectional drawing which shows the other Example which changed the joining surface of the joining form in this invention. It is sectional drawing which shows the other Example which changed the joining surface of the joining form in this invention. It is sectional drawing which shows the other Example which changed the joining surface of the joining form in this invention. It is sectional drawing which shows the other Example which changed the joining surface of the joining form in this invention. It is sectional drawing which shows the other Example which changed the joining surface of the joining form in this invention. It is sectional drawing which shows the other Example which changed the joining surface of the joining form in this invention. It is sectional drawing which shows the other Example which changed the joining surface of the joining form in this invention. It is sectional drawing which shows the other Example which changed the joining surface of the joining form in this invention. It is sectional drawing which shows the other Example which changed the joining surface of the joining form in this invention. 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 a liquid phase in the joining method of the aluminum member which concerns on this invention. It is explanatory drawing which shows the production | generation mechanism of a liquid phase in the joining method of the aluminum member which concerns on this invention. It is a front view which shows the observation surface position of a reverse T-shaped joining test piece and its junction part. It is a microscope picture which shows the junction part observed in FIG.

  The aluminum member joining method of the present invention and the aluminum structure joined using this joining method will be described below. Here, in this joining method, the aluminum members are exuded and joined by applying the joining method in accordance with the description in Patent Document 1 described above. First, the joining form of the 1st and 2nd aluminum member which is a to-be-joined member is demonstrated.

A. As shown in FIG. 1, when the first aluminum member is a long material, its long side portion, or when the first aluminum member is a flat plate material, its flat portion, The joining form which joins the edge part of the 2nd aluminum member which is also a long material with a predetermined angle is mentioned. Since the second aluminum member is joined so as to “stand” on the first aluminum member, such joining is hereinafter referred to as “standing up”. Each joining surface of the 1st and 2nd aluminum member is a single plane, and the part which contact | abutted these joining surfaces becomes a junction part. First, a standing joining mode in which the joining surface is a single plane will be described.

  When exudation joining is applied, there is no portion where the cross-sectional area gradually increases from the second aluminum member to the first aluminum member, such as a brazed fillet or a weld bead. If there is no part where the cross-sectional area gradually changes, for example, when a load such as a cantilever is applied to a part away from the joint part of the second aluminum member, stress concentrates on the joint part where the cross-sectional area changes suddenly. However, when the load condition is such that the stress exceeds the bonding strength, the bonded portion is deformed or broken.

  This is because the moment generated at the joint is constant under a certain load condition, and the stress generated at the outermost part of the joint becomes larger when the distance between the joint center and the outermost part is smaller, and the maximum stress becomes smaller when the distance is larger. Because it becomes. In other words, the maximum stress is large when the width of the joint is small and small when the width of the joint is large. And in the exudation joining, since the width | variety of this junction part is small, the maximum stress becomes large.

  For this reason, in the present invention, when both the aluminum members are erected and joined in a standing manner, the end of the second aluminum member on the side in contact with the first aluminum member is enlarged so that the joint surface is the first. It was made larger than the main body portion of the aluminum member No. 2. Specifically, the joining width of the joining portion of the second aluminum member and the first aluminum member is set to a surface parallel to the joining surfaces of the first and second aluminum members of the main body portion of the second aluminum member. It is larger than the minimum width of the cross section along. Thereby, the stress concentration in the outermost part of the joint is eliminated, and the occurrence of deformation and breakage at the joint can be suppressed.

  As an example of the joining form by such standing contact, as shown in FIG. 1, the joining form of the 2nd aluminum member by which the edge part was shape | molded in L shape, and a 1st aluminum member is mentioned. What is necessary is just to determine the dimension of L shape suitably.

  As an example of another joining form, as shown in FIG. 2, the end of the second aluminum member spreads in a funnel shape, and the one joined to the first aluminum member at the funnel-shaped end surface is used. Can be mentioned. What is necessary is just to determine a funnel-shaped end part shape and a dimension suitably.

  As another example of the joining form, as shown in FIG. 3, the unjoined end of the second aluminum member in FIG. 2 opposite to the end joined to the first aluminum member spreads. Are listed. The shape of the unjoined end is arbitrary and does not impair the effects of the present invention.

  1 to 3, the angle formed by the second aluminum member and the first aluminum member, that is, the angle formed by the center lines along the longitudinal direction of both members is a right angle ( 90 degrees), but is not limited to this angle. As shown in FIG. 4, the angle (θ) formed by the center lines (L1, L2) can be set in the range of 0 ° <θ <180 °, and the effect is exhibited. In the case of a general structural member, joining is often performed in a range of 30 ° <θ <150 °.

  Although the first and second aluminum members have been described on the premise that they are solid members, either one or both of the first and second aluminum members may be hollow members.

  Next, an example in which the joining surface of the present invention is a general joining form that is not limited to the joining form such as the above-described standing joining, and various joining surfaces are changed will be described. In general, the joining includes two members to be joined, and the joining surfaces are often composed of a single plane. However, in the exudation joining, the amount of liquid layer is smaller than that of normal brazing, and a filler metal is not used unlike welding. Therefore, when a member having high strength is selected as the member to be bonded, the bonding strength of the bonded portion is relatively weak. In such a case, if a load is applied, the joint will be deformed or broken.

  For this reason, in another embodiment of the present invention, the joining surface of the first aluminum member has a plurality of planes, and the joining surface of the second aluminum member also has the same plurality of planes. The plurality of joining surfaces of the first aluminum member and the plurality of joining surfaces of the second aluminum member corresponding thereto are respectively complementary. Instead, the joining surfaces of the first and second aluminum members are curved surfaces, and the curved surfaces are complementary.

  As an example of such a bonding form, as shown in FIG. 5, there is one in which a cross section of a bonding portion orthogonal to a plurality of planes has a vertical step shape. The dimensions of the step shape may be determined as appropriate, and the corners may be curved (R). Moreover, as shown in FIG. 6, what has the cross section of the junction part in the step shape of an obtuse angle is mentioned. Similar to the example of FIG. 5, the dimensions of the step shape may be determined as appropriate, and the corners may be curved (R). Furthermore, as shown in FIG. 7, there is one in which the cross section of the joint portion has a square shape. What is necessary is just to determine the angle between the straight lines of a square shape suitably. Moreover, as shown in FIG. 8, the thing where the junction part cross section is curvilinear is mentioned. What is necessary is just to determine the specific shape and dimension of a curve suitably.

  When such a joining mode is adopted, even when the aluminum member having a high strength is selected as the aluminum member and the joining strength of the joining surface is relatively weak, the joining area can be increased. As a result, the bonding strength of the entire bonded structure is increased, and even when a load is applied, it is difficult to break at the bonded portion.

  Another example in which the joint surface is variously changed will be described. In this example, the two joining planes of the first aluminum member and the corresponding two joining planes of the second aluminum member are complementary to each other, and the cross section of the joining portion has a right angle or an obtuse angle. It is a substantially L-shape formed.

  For example, as shown in FIG. 9, the second aluminum member has a substantially right-angled corner formed of two planes, and the first aluminum member has a bottom surface and side surfaces complementary to these two planes. . And the 1st aluminum member is standingly joined so that it may lean against the corner | angular part of a 2nd aluminum member, and the cross section of a junction part becomes L-shape. The end portion of the first aluminum member that is not joined may be formed into an L shape or a U shape, for example, or may not be formed into a specific shape.

  Instead of the second aluminum member of FIG. 9, as shown in FIG. 10, a second aluminum member having a substantially right-angled corner formed by two flat surfaces on one side of the convex portion provided on the long side portion is used. May be. The first aluminum member has a bottom surface and side surfaces complementary to the two planes of the second aluminum member. Also in this example, the first aluminum member is joined in a standing manner so as to lean against the corner portion of the second aluminum member, and the cross section of the joined portion becomes L-shaped. Similarly to the example shown in FIG. 9, the end portion of the first aluminum member that is not joined may be formed in an L shape or a U shape, for example, or may not be formed in a specific shape. .

  As another example in which the joint portion is substantially L-shaped, as shown in FIG. 11, the end portion of the first aluminum member is stepped to form a substantially right-angled corner portion composed of two planes. The second aluminum member has a flat plate shape and has a bottom surface and side surfaces complementary to the two planes of the first aluminum member. And by joining so that the edge part of a 2nd aluminum member may be faced | matched to the corner | angular part of a 1st aluminum member, the cross section of a junction part becomes L shape. The end portion of the second aluminum member that is not joined may be formed into, for example, an L shape or a U shape, or may not be formed into a specific shape.

  In the examples shown in FIGS. 9 to 11, the L-shaped dimension may be determined as appropriate. In addition to these examples, the same effect can be obtained if the cross section of the joint is L-shaped.

  Still another example in which the joint surfaces are variously changed will be described. In this example, the three joining planes of the first aluminum member and the corresponding three joining planes of the second aluminum member are complementary to each other, and the cross section of the joining portion has a right angle or an obtuse angle. It is an approximately U-shape.

  For example, as shown in FIG. 12, the second aluminum member has a U-shaped concave portion having a right angle or an obtuse angle at the long side portion, and the first aluminum member is complementary to the plane of the concave portion. For example, it has an end formed on an L-shaped surface. Then, by inserting and joining the L-shaped end portion of the first aluminum member into the concave portion of the second aluminum member, the cross section of the joint portion becomes a U-shape. The end portion of the first aluminum member that is not joined may be formed in an L shape or a U shape, for example, or may not be formed in a specific shape.

  Further, as another example in which the cross section of the joint portion is U-shaped, as shown in FIG. 13, two convex portions (13− 1, 13-2), and a concave portion is formed between the convex portions. The first aluminum member has an end portion having a bottom surface and both side surfaces complementary to the plane of the recess. Then, by inserting the end portion of the first aluminum member into the concave portion of the second aluminum member and joining, the cross section of the joint portion becomes a U-shape. Similarly to the example of FIG. 12, the end portion of the first aluminum member that is not joined may be formed in an L shape or a U shape, for example, or may not be formed in a specific shape.

  In the examples shown in FIGS. 12 and 13, the U-shaped dimensions may be appropriately determined. In addition to the above examples, the same effect can be obtained as long as the cross-section of the joint is U-shaped.

  Still another example in which the joint surfaces are variously changed will be described. In this example, a plurality of continuous joining planes of the first aluminum member and a plurality of continuous joining planes of the second aluminum member corresponding thereto are complementary to each other, and are orthogonal to the joining plane. Where the cross section of the joint is serrated, stepped or uneven (continuous body of rectangular grooves and upward rectangular protrusions), or the curved surfaces of the first and second aluminum members are complementary Thus, the cross section of the joint perpendicular to the joint curved surface is wavy.

  For example, as shown in FIG. 14, the joining surfaces of the first aluminum member and the second aluminum member are each composed of a plurality of stepped planes, and the corresponding planes between these members are complementary to each other. It is what. Accordingly, the cross section of the joint becomes a staircase shape by the joining.

  Further, as shown in FIG. 15, the joining surfaces of the first aluminum member and the second aluminum member are each composed of a plurality of serrated planes, and the corresponding planes between these members are complementary. Is. Accordingly, the cross section of the joint becomes serrated by joining.

  Further, as shown in FIG. 16, the joining surfaces of the first aluminum member and the second aluminum member are each composed of a plurality of concave and convex surfaces, and the corresponding concaves and convexes between these members are complementary. It is what. Therefore, the cross section of the joint becomes uneven due to the joining.

  Further, as shown in FIG. 17, the joining surfaces of the first aluminum member and the second aluminum member are each composed of a wavy curved surface, and the corresponding wavy curved surfaces are complementary to each other. Accordingly, the cross section of the bonded portion becomes wavy due to the bonding.

These staircase-shaped dimensions, sawtooth-shaped dimensions, uneven-shaped dimensions, and wavy dimensions may be appropriately determined.
In the examples shown in FIGS. 4 to 17 as well, the joining width of the joining portion of the first aluminum member and the second aluminum member is the second aluminum parallel to the joining surfaces of the first and second aluminum members. It is larger than the minimum width of the cross section of the body of the member.

  As mentioned above, although the joining form of the 1st and 2nd aluminum member was explained in full detail, in any joining form, the thing whose aluminum member itself intensity | strength is high is selected, and the joining strength of a junction part is relatively weak Even so, the bonding area can be increased. As a result, the bonding strength of the bonded structure as a whole is increased, and a special effect is obtained that it is difficult to break at the bonded portion even when a load is applied.

Next, the seepage joining applied in the present invention will be described in detail.
B. Combination of Joined Members In the method for joining aluminum members according to the present invention, a first aluminum member that is one joined member and a second aluminum member that is the other joined member are joined. Here, the aluminum member means an aluminum alloy material or a pure aluminum material, and the aluminum members may be joined together with the same alloy composition or with different alloy compositions.

C. Generation of Liquid Phase In the exudation joining of the aluminum member applied in the present invention, as described in Patent Document 1, at least one of the first and second aluminum members, that is, the first and second The ratio of the mass of the liquid phase generated in the aluminum member with respect to the total mass of the aluminum member (hereinafter referred to as “liquid phase ratio”) of either one or both of the aluminum members is 5% or more and 35% or less. It is necessary to join at a temperature. If the liquid phase ratio exceeds 35%, the amount of the liquid phase to be generated is too large, and the aluminum member cannot maintain its shape and is greatly deformed. 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 ratio during heating. Therefore, the liquid phase ratio defined in the present invention is obtained by equilibrium calculation. Specifically, the temperature is calculated from the alloy composition and the highest temperature achieved during heating by thermodynamic equilibrium calculation software such as Thermo-Calc.

  The generation mechanism of the liquid phase will be described. FIG. 18 schematically shows a phase diagram of an Al—Si alloy which is a typical binary eutectic alloy. When an aluminum member 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. 19A, crystal precipitates are distributed in the matrix divided by the crystal grain boundaries. Here, when the generation of the liquid phase starts, as shown in FIG. 19B, the crystal grain boundary with a large segregation of the crystal precipitate distribution melts to become a liquid phase. Next, as shown in FIG. 19 (c), the periphery of the Si crystal precipitate particles and the intermetallic compound, which are the main additive element components dispersed in the matrix of the aluminum alloy, is melted into a spherical shape to form a liquid phase. Further, as shown in FIG. 19 (d), the 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 boundary and the surface are diffused by diffusion in the solid phase. Move to. Next, when the temperature rises to T2 as shown in FIG. 17, the liquid phase amount increases from the state diagram. As shown in FIG. 18, when the Si concentration of one aluminum member 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, the structure immediately before melting may not have crystal precipitates in the matrix as shown in FIG. In this case, as shown in FIG. 20 (b), after first melting at the grain boundary to become a liquid phase, as shown in FIG. 20 (c), the liquid phase starts from a location where the solute element concentration is locally high in the matrix. Occurs. As shown in FIG. 20 (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, as in the case of c1, and diffuses 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. Thus, the seepage joining applied by the present invention utilizes a liquid phase generated by partial melting inside the aluminum member, and can realize both joining and shape maintenance.

D. Behavior of metal structure in joining The behavior of the metal structure after the liquid phase occurs until joining is explained. As shown in FIG. 21, an inverted T-shaped joining test piece using an aluminum member A that generates a liquid phase and an aluminum member B that is joined to the aluminum member A was joined, and the observation surface shown in the figure was observed with a microscope. As described above, a very small amount of liquid phase generated on the surface of the aluminum member A during the bonding fills the gap with the counterpart aluminum member B in which the oxide film is destroyed by the action of flux or the like. Next, the liquid phase in the vicinity of the bonding interface between the two members moves into the aluminum member B, and accordingly, the solid phase α phase crystal grains of the aluminum member A in contact with the bonding interface enter the aluminum member B. Growing towards. On the other hand, the crystal grains of the aluminum member B also grow to the aluminum member A side.

  When the aluminum member B is an alloy that does not generate a liquid phase, as shown in FIG. 22 (a), the aluminum member B is joined as a structure in which the structure of the aluminum member A enters the aluminum member B near the joining interface. The Therefore, a metal structure other than the aluminum member A and the aluminum member B does not occur at the bonding interface. When the aluminum member B is also an alloy that generates a liquid phase, as shown in FIG. 22B, the two members have a completely integrated structure, and the bonding interface cannot be determined.

  On the other hand, when a brazing sheet clad with a brazing material is used as the aluminum member A and a member that does not generate a liquid phase is used as the aluminum member B, a fillet is formed at the joint as shown in FIG. A eutectic structure is observed. Thus, in FIG.22 (c), it differs from the joining structure | tissue formed in FIG.22 (a), (b). In the brazing method, since the liquid phase braze fills the joint portion to form a fillet, a eutectic structure different from the surrounding is formed in the joint portion. Also, in the welding method, since the joint portion is locally melted, the metal structure is different from other portions. On the other hand, in the seepage joint applied in the present invention, the metal structure of the joint portion is composed of only the members to be joined, or the joint structure of both the members to be joined is used. It differs from the joint structure by attaching or welding.

  Due to such joining behavior, the shape change in the vicinity of the joining site hardly occurs after the joining process. That is, the shape change after joining, such as a bead of a welding method and a fillet by a brazing method, hardly occurs in the joining method according to the present invention. In spite of this, it is possible to join by metal bonding as well as welding and brazing. For example, when a drone cup type laminated heat exchanger is assembled using a brazing sheet (a brazing material clad rate is 5% on one side), the molten brazing material concentrates on the joint after brazing heating, so that lamination is performed. Heat exchanger height is reduced by 5-10%. Therefore, it is necessary to consider the decrease in product design. In the exudation joining applied in the present invention, since the dimensional change after joining is extremely small, a highly accurate product design is possible.

E. Destruction of the oxide film An oxide film is formed on the surface layer of the aluminum member, which inhibits bonding. Therefore, it is necessary to destroy the oxide film in joining. In the seepage bonding applied in the present invention, any of the methods shown in the following D-1 or D-2 is adopted in order to destroy the oxide film.

E-1. Fracture of oxide film by flux In this method, flux is applied to at least the joint portion in order to destroy the oxide film. As the flux, a fluoride flux such as KAlF4 or CsAlF4 used for brazing an aluminum material or a chloride flux such as KCl or NaCl 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.

  Further, when using a fluoride-based flux, if Mg exceeds 0.5 mass% in the first and second aluminum members, the flux and Mg react to cause an oxide film destruction action of the flux. Damaged. Therefore, as defined in claims 1 and 3, both the first and second aluminum members are regulated to have an Mg content of 0.5 mass% (hereinafter simply referred to as “%”) or less. It shall consist of aluminum material. Here, Mg: 0.5 mass% or less includes the case where Mg is not contained or the case where it is contained in a very small amount as an inevitable impurity level. In addition, as long as 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 first and second aluminum members.

E-2. Breakage of oxide film due to getter action of Mg When a predetermined amount of Mg is added to the aluminum member, the oxide film is broken and joining is possible without applying flux to the joint. In this case, as in the case of vacuum fluxless brazing, when the aluminum member 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 member.

  When the oxide film is destroyed by the getter action of Mg, in order to suppress the formation of the oxide film, the bonding is performed in a vacuum or the above non-oxidizing atmosphere. In the case of surface bonding or bonding in a closed space, bonding may be possible in a dry atmosphere. In the case of bonding in a non-oxidizing atmosphere or a dry atmosphere, it is preferable to suppress the dew point to −25 ° C. or lower.

  In order to destroy the oxide film by the getter action of Mg, one of the first and second aluminum members is made of an aluminum material having an Mg content of 0.2% or more and 2.0% or less. When the Mg content is less than 0.2% by mass, a sufficient getter action cannot be obtained and good bonding cannot be achieved. On the other hand, if it exceeds 2.0% by mass, Mg reacts with oxygen in the atmosphere on the surface, and a large amount of oxide MgO is generated and bonding is inhibited. The reason why the Mg content is set to 0.2% or more and 2.0% or less for only one aluminum member is that it is sufficient if the getter action of Mg by one aluminum member is obtained. In the other aluminum member, the Mg content is not limited to 0.2% or more, but bonding is inhibited when a large amount of MgO is generated, so the Mg content is regulated to 2.0% or less. Here, Mg: 2.0% or less includes the case where Mg is not contained, or the case where a very small amount is contained as an inevitable impurity level. In addition, in one aluminum member, if the Mg content satisfies the condition of 0.2% or more and 2.0% or less, the type and content of the other elements are not limited, and the other aluminum member contains Mg. There is no limitation on the type and content of other elements as long as the condition of 2.0% or less is satisfied.

F. Bonding conditions The time during which the liquid phase ratio is 5% or more and 35% or less is preferably 30 seconds or more and 3600 seconds or less, and more preferably 60 seconds or more and 1800 seconds or less. If it is less than 30 seconds, the liquid phase may not be sufficiently filled in the joint, and if it exceeds 3600 seconds, the shape change of the member to be joined may not be reliably suppressed.
The difference between the solidus temperature and the liquidus temperature of the aluminum member that generates the liquid phase is preferably 10 ° C. or higher. If it is less than 10 degreeC, the temperature range in which a solid and a liquid coexist will become narrow, and control of the amount of generated liquid phases may become difficult.
Furthermore, in an aluminum alloy material that generates a liquid phase, it is preferable that the crystal grain size of the matrix after heating at the bonding temperature is 50 μm or more. If the thickness is less than 50 μm, grain boundary slip is likely to occur due to its own weight, and deformation may be promoted when the joining time is increased. The crystal grain size was measured by a cutting method based on JIS H: 501.

G. Material of Aluminum Member Suitable for the Present Invention As an aluminum member that generates a predetermined liquid phase ratio, the Mg content is regulated to 0.5% or less or 0.2% to 2.0%, and Si: It contains 6 to 3.5% as an essential element, Cu: 0.05 to 0.5%, Fe: 0.05 to 1.0%, Zn: 0.2 to 1.0%, Mn: 0.00. One or more selected from 1 to 1.8% and Ti: 0.01 to 150.3% are further contained as selective additional elements, and the balance is made of an aluminum alloy composed of Al and inevitable impurities. An aluminum alloy material is preferably used.

  When an aluminum alloy material made of such an Al—Si alloy or Al—Si—Mg alloy is used as an aluminum member that generates a liquid phase, the Si content is X (%), and the joining temperature T is 660. It is preferable to control so that −39.5X ≦ T ≦ 660−15.7X and T ≧ 577. This achieves even better bonding.

  As another aluminum member that generates a predetermined liquid phase ratio, Mg content is regulated to 0.5% or less or 0.2% to 2.0%, Cu: 0.7 to 15.0% Containing as an essential element, Si: 0.05-0.8%, Fe: 0.05-1.0%, Zn: 0.2-1.0%, Mn: 0.1-1.8% and Ti: One or more elements selected from 0.01 to 0.3% are further contained as selective additive elements, and an aluminum alloy material made of an aluminum alloy composed of Al and inevitable impurities is also preferably used. It is done.

  When an aluminum alloy material made of such an Al—Cu alloy or Al—Cu—Mg alloy is used as an aluminum member that generates a liquid phase, the Cu content is defined as Y (%), and the junction temperature T is set to It is preferable to control so that 660-15.6Y ≦ T ≦ 660-6.9Y and T ≧ 548. This achieves even better bonding.

H. Stress applied to the aluminum member at the time of joining In the joining of the present invention, it is not always necessary to apply pressure to the joining surface as long as the first and second aluminum members are in contact with each other at the joint. However, in an actual product manufacturing process, stress is often applied to both aluminum members with a jig or the like in order to fix the aluminum members together or reduce the clearance. Also, stress is generated in the aluminum member due to its own weight. At this time, the stress which generate | occur | produces in each site | part in each aluminum member is calculated | required from a shape and a load. For example, the calculation is performed using a structural calculation program or the like. In the present invention, the maximum stress (maximum stress) among the stresses generated in each part of the aluminum member that generates a liquid phase at the time of joining is P (kPa), and the liquid phase ratio in the aluminum alloy that is the aluminum member is V When joining, it is preferable to join so as to satisfy P ≦ 460-12V. The value shown on the right side of this equation is the critical stress. If a stress exceeding this value is applied to an aluminum member that generates a liquid phase, the aluminum member may be greatly deformed even if the liquid phase rate is within 35%. is there.
When a liquid phase is generated from both aluminum members, P ≦ 460-12V is calculated for each of the aluminum members using the respective stress P and liquid phase ratio V. Join to meet at the same time.

I. In the joining of the present invention, since the amount of liquid phase generated in the aluminum member is very small, the aluminum member needs to be arranged so that both aluminum members are in contact with each other. However, a slight gap may be generated between the two aluminum members due to warpage or undulation of the material. In particular, undulations with a wavelength of 25 to 2500 μm are not a size that can be ignored as a gap, and it is difficult to correct with a jig press.

  In the present invention, when the arithmetic mean waviness Wa1 and Wa2 obtained from the unevenness of the surfaces of the two aluminum members before joining satisfy Wa1 + Wa2 ≦ 10 (μm), further sufficient joining is obtained. . The arithmetic average waviness Wa1 and Wa2 are defined by JISB0633, and are obtained from waviness curves measured with a laser microscope or a confocal microscope in which a cutoff value is set so as to detect only a wavelength of 25 to 2500 μm. It is done.

J. et al. Joining Method In the joining method of the present invention, the aluminum member is usually heated in a furnace. There is no restriction | limiting in particular in the shape of a furnace, For example, the continuous furnace etc. which are used for manufacture of the batch furnace of a one-chamber structure, the heat exchanger for motor vehicles, etc. can be used. The atmosphere in the furnace is not limited, but is preferably performed in a non-oxidizing atmosphere as described above.

  An oxide film is formed on the surface layer of the aluminum material, which inhibits bonding. Therefore, it is necessary to destroy the oxide film in joining. In the bonding method according to the present invention, it is preferable to apply a flux to the bonding portion in order to destroy the oxide film. Further, in order to suppress the formation of an oxide film, it is preferable to perform bonding in an atmosphere of a non-oxidizing gas such as nitrogen. It is particularly preferable to apply a flux to the joint and join in a non-oxidizing gas atmosphere. In addition, when Mg is added to the aluminum alloy material, the getter action of the Mg oxide film on the surface can be achieved by using a furnace in a vacuum, a non-oxidizing atmosphere or an air atmosphere without applying a flux to the joint. Can be removed.

  The present invention provides a simple method for joining aluminum members that does not require a solubilizing material or brazing material. Further, there is provided an aluminum structure having no strength at the joint portion and having sufficient strength.

c ·· Si concentration c1 ·· Si concentration c2 ·· Si concentration L1 ·· Center line along the longitudinal direction of the first aluminum member L2 ·· Center line along the longitudinal direction of the second aluminum member T ··· Temperature above T1 ·· Te Temperature higher than T2 ·· T1 Temperature above T3 ·· Ts2 Te ·· Solidus temperature Ts2 ·· Solidus temperature

Claims (8)

A method of joining a flat portion of a first aluminum member and an end portion of a second aluminum member, wherein at least one of the first and second aluminum members is generated in the aluminum member with respect to the total mass thereof In the joining method of joining at a temperature at which the ratio of the mass of the liquid phase is 5% or more and 35% or less,
The joining width of the joining portion of the first and second aluminum members is the minimum width of the cross section along the plane parallel to the joining surface of the first and second aluminum members of the main body portion of the second aluminum member. larger than,
The first and second aluminum members are made of an aluminum material regulated to Mg: 0.5% by mass or less,
The joining is performed in a non-oxidizing atmosphere in a state in which a fluoride-based or chloride-based flux is applied to the joining portion . A method of joining a flat portion of a first aluminum member and an end portion of a second aluminum member, wherein at least one of the first and second aluminum members is generated in the aluminum member with respect to the total mass thereof In the joining method of joining at a temperature at which the ratio of the mass of the liquid phase is 5% or more and 35% or less,
  The joining width of the joining portion of the first and second aluminum members is the minimum width of the cross section along the plane parallel to the joining surface of the first and second aluminum members of the main body portion of the second aluminum member. Bigger than
The first aluminum member is made of an aluminum material containing Mg: 0.2% by mass or more and 2.0% by mass or less, and the second aluminum member is regulated to have an Mg content of 2.0% by mass or less. Made of aluminum material,
The said joining is performed in a vacuum, a non-oxidizing atmosphere, or air | atmosphere, The joining method of the aluminum member characterized by the above-mentioned. The method for joining aluminum members according to claim 1 or 2 , wherein the joining surfaces of the first and second aluminum members are each formed from a single plane . 3. The aluminum member according to claim 1, wherein the joining surfaces of the first and second aluminum members are each composed of a plurality of planes complementary to each other or a curved surface complementary to each other. Joining method. 5. The joint surfaces of the first and second aluminum members are each composed of two planes complementary to each other, and the cross section of the joint perpendicular to the joint surfaces is substantially L-shaped. The joining method of the aluminum member as described in 2. The joint surface of each of the first and second aluminum members is composed of three planes complementary to each other, and a cross section of a joint portion orthogonal to the joint surface is substantially U-shaped. 4. A method for joining aluminum members according to 4 . Each of the joint surfaces of the first and second aluminum members is composed of a plurality of planes complementary to each other, and the cross section of the joint perpendicular to the joint surfaces is sawtooth, stepped or uneven. The method for joining aluminum members according to claim 4 . 5. The aluminum member according to claim 4, wherein each of the joining surfaces of the first and second aluminum members has a curved surface that is complementary between the two members, and a section of the joining portion that is orthogonal to the joining surface is corrugated. Joining method.

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