Aluminum alloy structure, heating joining method, and aluminum alloy extruded material and method of manufacturing the same

Abstract

An aluminum alloy structure is characterized by being obtained by heating and joining one joined member to another joined member, the one joined member containing 1.80 to 3.00 mass% of Si, 0.10 to 1.60 mass% of Mn, 0.01 to 0.70 mass% of Fe, the balance being Al and unavoidable impurities, the average grain diameter in the outermost layer of the one joined member at the joined portion of the one joined member and the other joined member being 200 μm or less, and the average grain diameter in the cross section at the position of 100 μm in depth of the portion having the smallest width of the one joined member being 400 μm or more. According to the present invention, an aluminum alloy structure which can be joined in a single layer, thereby enabling a manufacturing process to be simplified, has good joint properties, and can suppress deformation during heating and joining, and a method for manufacturing an aluminum alloy extruded material can be provided.

Description

Technical Field

[0001] This invention relates to aluminum alloy structures, heating joining methods, and aluminum alloy extrusion materials and manufacturing methods thereof. More specifically, it relates to aluminum alloy structures capable of joining with other components by their own action without the use of joining components such as brazing filler metal or filler metal, as well as aluminum alloy extrusion materials and manufacturing methods thereof. Background Technology

[0002] When manufacturing structures such as heat exchangers that are made of aluminum alloy, it is necessary to join the aluminum alloy materials together. Various methods are known for joining aluminum alloy materials, among which brazing is the most common.

[0003] As a method for manufacturing heat exchangers and the like using a joining method based on the brazing method for aluminum alloy materials, one method is to use a brazing plate coated with a brazing filler metal made of Al-Si alloy (Patent Document 1). However, when manufacturing the coating material, there are manufacturing difficulties such as the need to manufacture each layer separately and then overlap and join them, which makes the manufacturing process complicated.

[0004] In addition, other methods for manufacturing heat exchangers and the like using aluminum alloy materials based on brazing include: methods using aluminum alloy materials coated with powdered brazing filler metal; methods that, after assembling the various materials, separately apply or coat with a pre-placed brazing material, brazing paste, or other brazing filler metal to the parts to be joined; etc. (Patent Documents 2, 3). However, even in these methods, the process of preparing and applying brazing filler metal separately, in addition to the aluminum alloy material, presents manufacturing difficulties due to the increased complexity of the manufacturing process.

[0005] Therefore, instead of the aforementioned methods of using brazing plates with cladding materials and methods of using aluminum alloy materials coated with powdered brazing filler metal, which would make the manufacturing process of aluminum alloy materials and aluminum alloy structures more complicated, there is a method of using a single-layer brazing plate (Patent Document 4).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2008-303405

[0009] Patent Document 2: Japanese Patent Application Publication No. 2011-136358

[0010] Patent Document 3: Japanese Patent Application Publication No. 09-047892

[0011] Patent Document 4: International Publication No. 2014 / 184880 Summary of the Invention

[0012] The problem the invention aims to solve

[0013] However, single-layer brazing plates are able to bond by partially melting themselves, so there is a concern that material deformation becomes significant when heated.

[0014] In addition, single-layer brazing plates join other components through their own action (the liquid phase seeping from the base material) without using joining components such as brazing filler metal or filler metal. Therefore, compared with existing methods that use brazing plates coated with brazing filler metal or aluminum alloy materials coated with powdered brazing filler metal, the amount of liquid phase used in brazing is less, so there is a concern about reduced heat bonding.

[0015] Therefore, the object of the present invention is to provide an aluminum alloy structure and an aluminum alloy extrusion material that can be joined in a single layer, thereby simplifying the manufacturing process, providing good bonding, and suppressing deformation during heat joining.

[0016] Solution for solving the problem

[0017] The inventors conducted in-depth research and as a result invented an aluminum alloy structure that, as a joined component, can be joined in a single layer by controlling the alloy composition and crystal structure, thereby simplifying the manufacturing process, exhibiting good joinability, and suppressing deformation during heat joining, as well as an aluminum alloy extrusion material and a method for manufacturing the same.

[0018] That is, the present invention (1) provides an aluminum alloy structure, characterized in that it is formed by heating and joining one component made of aluminum alloy to another component made of either aluminum alloy or pure aluminum.

[0019] The aforementioned joined component contains 1.80–3.00% by mass Si, 0.10–1.60% by mass Mn, 0.01–0.70% by mass Fe, with the balance being Al and unavoidable impurities.

[0020] In the outermost layer of the aforementioned joined member at the joint between the aforementioned joined member and the aforementioned joined member, the average grain diameter is less than 200 μm, and in the cross section at a depth of 100 μm in the thinnest part of the aforementioned joined member, the average grain diameter is more than 400 μm.

[0021] In addition, the present invention (2) provides a heating joining method, characterized in that it is the heating joining method for the aluminum alloy structure described in (1), wherein,

[0022] The average grain diameter of the outermost layer of the metallographic structure supplied for bonding at 575°C during heat bonding is less than 200 μm, and the average grain diameter of the cross section at a depth of 100 μm in the thinnest part is greater than 400 μm.

[0023] In addition, the present invention (3) provides an aluminum alloy extrusion material, characterized in that it is an aluminum alloy extrusion material with a single layer having a heating bonding function.

[0024] The aluminum alloy extruded material contains 1.80~3.00% by mass Si, 0.10~1.60% by mass Mn, 0.01~0.70% by mass Fe, with the balance being Al and unavoidable impurities.

[0025] The width of the thinnest part of the cross-section perpendicular to the extrusion direction is 0.6 mm or more.

[0026] After a heating test in which the temperature is raised from 450°C to 575°C over 4 to 15 minutes and held at 575 to 615°C for 5 to 40 minutes, the average grain diameter of the outermost layer of the surface to be bonded is less than 200 μm, and the average grain diameter of the cross section at a depth of 100 μm in the thinnest part of the aforementioned wall thickness is greater than 400 μm.

[0027] In addition, the present invention (4) provides a method for manufacturing an aluminum alloy extruded material, characterized in that it is the same as the method for manufacturing an aluminum alloy extruded material of (3), and the manufacturing method has the following steps:

[0028] The casting process involves casting ingots containing 1.80–3.00% by mass Si, 0.10–1.60% by mass Mn, 0.01–0.70% by mass Fe, with the balance being Al and unavoidable impurities; and

[0029] In the hot extrusion process, the aforementioned ingot is hot-extruded while the temperature of the ingot is above 400°C and below 550°C, forming a shape in which the width of the thinnest part of the cross section perpendicular to the extrusion direction is 0.6 mm or more.

[0030] In addition, the present invention (5) provides a method for manufacturing aluminum alloy extruded material of (4), characterized in that a homogenization process is provided after the aforementioned casting process, wherein the homogenization process is performed by homogenizing the aforementioned ingot at a temperature below 570°C.

[0031] The effects of the invention

[0032] According to the present invention, an aluminum alloy structure and an aluminum alloy extruded material can be provided, which can be joined in a single layer, thereby simplifying the manufacturing process, providing good bonding, and suppressing deformation during heat joining. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the state of Al-Si alloy, a representative binary eutectic alloy.

[0034] Figure 2 This is an explanatory diagram illustrating the formation mechanism of the liquid phase in the aluminum alloy in the aluminum alloy used in the bonding of the aluminum alloy extrusion material of the present invention.

[0035] Figure 3 This is an explanatory diagram illustrating the formation mechanism of the liquid phase in the aluminum alloy in the aluminum alloy used in the bonding of the aluminum alloy extrusion material of the present invention.

[0036] Figure 4 This is a schematic diagram of the state of Al-Si alloy, a representative binary eutectic crystal.

[0037] Figure 5 The results are observed in the cross-sectional microstructure along the wall thickness direction after a heating test simulating the heating bonding of the aluminum alloy extruded material of the present invention.

[0038] Figure 6 The results are microstructural observations of the outermost layer of the aluminum alloy extruded material after a heating test simulating the heating bonding of the aluminum alloy extruded material of the present invention, with the cross-section perpendicular to the depth direction.

[0039] Figure 7 The microstructure observation results are obtained from a section perpendicular to the depth direction at a depth of 100 μm after a heating test simulating the heating bonding of the aluminum alloy extruded material of the present invention.

[0040] Figure 8 This is a diagram of the inverted T-shaped joint test. Detailed Implementation

[0041] The aluminum alloy structure of the present invention is characterized in that it is formed by thermally joining one bonding member made of aluminum alloy with another bonding member made of either aluminum alloy or pure aluminum. The aforementioned bonding member contains 1.80 to 3.00% by mass of Si, 0.10 to 1.60% by mass of Mn, 0.01 to 0.70% by mass of Fe, with the balance being Al and unavoidable impurities. In the outermost layer of the aforementioned bonding member at the joint between the aforementioned bonding member and the aforementioned other bonding member, the average grain diameter is 200 μm or less. In the cross-section at a depth of 100 μm in the thinnest part of the aforementioned bonding member, the average grain diameter is 400 μm or more.

[0042] The aluminum alloy structure of the present invention is an aluminum alloy structure formed by heating and joining one bonding member made of aluminum alloy to another bonding member made of either aluminum alloy or pure aluminum.

[0043] In this invention, one of the joined components of the aluminum alloy structure is made of aluminum alloy. That is, one joined component is made of aluminum alloy and is formed from aluminum alloy.

[0044] The aluminum alloy forming a joined component contains 1.80 to 3.00% by mass of Si, 0.10 to 1.60% by mass of Mn, 0.01 to 0.70% by mass of Fe, with the balance being Al and unavoidable impurities.

[0045] Si is an element that forms an Al-Si liquid phase during heat bonding, which aids in bonding. If the Si content of the aluminum alloy is less than 1.80% by mass, a sufficient amount of liquid phase cannot be formed, resulting in reduced bonding strength. Furthermore, if the Si content exceeds 3.00% by mass, it contains a large amount of elemental Si, which significantly increases tool wear during the aluminum alloy manufacturing process. Therefore, the Si content of the aluminum alloy forming a bonded component is specified to be 1.80 to 3.00% by mass. The lower limit of the Si content in the aluminum alloy forming a bonded component is preferably 2.00% by mass. The upper limit of the Si content in the aluminum alloy forming a bonded component is preferably 2.80% by mass. The Si content can be set within a range combining the above upper and lower limits.

[0046] Mn is an element that adjusts the crystal structure of aluminum alloy materials, helping to improve heat bonding and suppress deformation during heat bonding. If the Mn content of the aluminum alloy is less than 0.10% by mass, the grain diameter of the present invention cannot be obtained, and the deformation during heat bonding becomes larger. In addition, if the Mn content exceeds 1.60% by mass, the deformation resistance of the aluminum alloy material increases, which may make processing difficult in the manufacturing process of aluminum alloy materials. Therefore, the Mn content of the aluminum alloy forming a bonded component is specified to be 0.10 to 1.60% by mass. The lower limit of the Mn content of the aluminum alloy forming a bonded component is preferably 0.20% by mass, more preferably 0.30% by mass. In addition, the upper limit of the Mn content of the aluminum alloy forming a bonded component is preferably 1.40% by mass, more preferably 1.20% by mass, more preferably 1.00% by mass, and more preferably 0.80% by mass. The Mn content can be set to a range formed by combining the above upper and lower limits.

[0047] Fe is an element that helps improve the strength of aluminum alloy materials. If the Fe content of the aluminum alloy is less than 0.01% by mass, it requires the use of extremely high-purity aluminum matrix metal, which increases costs. Furthermore, if the Fe content exceeds 0.70% by mass, Al-Fe-Si compounds are formed, reducing the amount of Si that contributes to liquid phase formation during heat bonding, thus decreasing heat bonding properties. Therefore, the Fe content of the aluminum alloy forming a bonded component is specified to be 0.01 to 0.70% by mass. The lower limit of the Fe content of the aluminum alloy forming a bonded component is preferably 0.05% by mass, more preferably 0.10% by mass, and even more preferably 0.15% by mass. The upper limit of the Fe content of the aluminum alloy forming a bonded component is preferably 0.60% by mass, more preferably 0.50% by mass, and even more preferably 0.40% by mass. The Fe content can be set within a range combining the above upper and lower limits.

[0048] The other joined component of the aluminum alloy structure of the present invention is made of aluminum alloy or pure aluminum. That is, the other joined component is made of aluminum alloy or pure aluminum material and is formed from aluminum alloy or pure aluminum. When the other joined component is made of aluminum alloy, the other joined component may have the same alloy composition as the aluminum alloy material forming one joined component, or it may have a different alloy composition.

[0049] Next, the metallographic structure of the aluminum alloy structure of the present invention will be described.

[0050] In the metallographic structure of a joined component of the aluminum alloy structure of the present invention, the grains are made fine at the joining surface to improve heat-bonding properties, and the grains inside the material are made coarse to suppress deformation during heat-bonding. These metallographic structures should ideally be achieved just before the formation of a liquid phase. However, the aforementioned metallographic structures are usually maintained after heat-bonding, and therefore can be confirmed by any of the following: a structure after heat-bonding, a material subjected to a heat test simulating heat-bonding, or a material heated to just before the formation of a liquid phase and then cooled. One method of heat treatment is as follows: heating to 580°C to 620°C at an average heating rate of 5 to 100°C / min, holding at 580°C to 620°C for approximately 0 to 20 minutes, and then cooling.

[0051] In the joint between one joined member and another in the aluminum alloy structure of the present invention, the average grain diameter of the outermost layer of one joined member is 200 μm or less. The average grain diameter of the outermost layer is measured in a cross-section (i.e., a section perpendicular to the depth direction at a depth of 0 to 10 μm) along the surface of the joined member, using the surface of the joined member used for joining as a depth reference (zero position). However, in the joint, due to the presence of a liquid phase generated by one joined member, the position of the surface of one joined member is sometimes difficult to determine definitively. In this case, the average grain diameter of the outermost layer can also be measured in a region near the joint, considered equivalent to the joining surface of one joined member, using the surface of one joined member as a depth reference, in a cross-section (0 to 10 μm) along the surface of one joined member.

[0052] The average grain diameter of the outermost layer affects the heat-bonding properties during the fabrication of aluminum alloy structures. When the average grain diameter of the outermost layer is greater than 200 μm, the heat-bonding properties during the fabrication of aluminum alloy structures decrease. That is, during heat bonding, an Al-Si liquid phase is generated at the grain boundaries of the components to be bonded. This liquid phase is supplied to the bonding portion via the grain boundaries, thereby filling the bonding portion and solidifying to achieve bonding. However, when the average grain diameter of the outermost layer of the components to be bonded is large, there are fewer grain boundaries, thus reducing the amount of liquid phase supplied to the bonding portion, raising concerns about insufficient bonding. For the above reasons, the average grain diameter of the outermost layer of the components to be bonded is specified to be 200 μm or less. Preferably, the average grain diameter of the outermost layer of the components to be bonded is 180 μm or less, more preferably 160 μm or less, and even more preferably 140 μm or less.

[0053] In the aluminum alloy structure of the present invention, the average grain diameter is 400 μm or more in a cross-section at a depth of 100 μm in the thinnest part of the joined component. The average grain diameter of the cross-section at a depth of 100 μm in the thinnest part is measured with the surface of the joined component as the reference depth (zero position) in a cross-section at a depth of 100 μm along the surface of the joined component (i.e., a cross-section perpendicular to the depth direction at a depth of 100 μm).

[0054] The average grain diameter of the cross-section at a depth of 100 μm in the thinnest part of the wall affects the deformation during heat bonding. When the average grain diameter of the cross-section at a depth of 100 μm in the thinnest part of the wall is less than 400 μm, the deformation during heat bonding becomes significant. That is, during heat bonding, when an Al-Si liquid phase forms at the grain boundaries, a large amount of grain boundary slip occurs when the average grain diameter is small. Since the thinnest part of the wall has particularly low rigidity, it is greatly affected by this slip, resulting in greater deformation and concerns about not meeting dimensional specifications. Based on the above reasons, the average grain diameter of the cross-section at a depth of 100 μm in the thinnest part of the wall is specified to be 400 μm or more.

[0055] It should be noted that the joint surface of one of the joined components of the aluminum alloy structure of the present invention can be at the same location as the thinnest part of the wall or at different locations.

[0056] From the viewpoint of resistance to deformation, the shape of the aluminum alloy structure of the present invention preferably has a width of 0.6 mm or more for the thinnest portion of the joined component. When the width is less than 0.6 mm, the rigidity of the material decreases, and there are concerns that the metallographic structure of the present invention cannot be obtained.

[0057] The heating bonding method of the present invention is characterized in that it is a heating bonding method for aluminum alloy structures of the present invention, wherein the average grain diameter of the outermost layer of the metallographic structure supplied for bonding at 575°C during heating bonding is less than 200 μm, and the average grain diameter of the cross section at a depth of 100 μm in the thinnest part of the wall thickness is more than 400 μm.

[0058] That is, the heating joining method of the present invention is as follows: in order to obtain the aluminum alloy structure of the present invention, a heating joining method is used to heat and join one joined member to another joined member. In the heating for the heating joining of the one joined member to the other joined member, when the temperature of one joined member reaches 575°C, the average grain diameter of the outermost layer of the metallographic structure of the joined member is 200 μm or less, and the average grain diameter of the cross section at the depth of 100 μm of the thinnest part is 400 μm or more.

[0059] In the heat bonding method of the present invention, 575°C is the temperature just before a liquid phase is generated within a component to be bonded. Therefore, the heat bonding method of the present invention is as follows: for the metallographic structure just before the liquid phase is generated, by making the average grain diameter of the outermost layer of the bonding surface less than 200 μm, numerous liquid phase supply paths are formed on the surface, resulting in good brazing properties; and by making the average grain diameter of the cross-section at a depth of 100 μm in the thinnest part of the wall greater than 400 μm, grain boundary slip within the material is prevented, and deformation is reduced. Furthermore, the metallographic structure formed at 575°C is substantially maintained even after subsequent heating and cooling.

[0060] In the heat bonding method of the present invention, for example, by heating a component manufactured using a manufacturing method for a component to be bonded at an average heating rate of 5 to 100°C / min to 580°C to 620°C and holding it at 580°C to 620°C for about 0 to 20 minutes, it is possible to make the average grain diameter of the outermost layer of the metallographic structure of the surface to be bonded of the component less than 200 μm and the average grain diameter of the cross section at a depth of 100 μm in the thinnest part of the wall thickness more than 400 μm.

[0061] The aluminum alloy extrusion material of the present invention is characterized in that it is a single-layer aluminum alloy extrusion material with a heat-bonding function, wherein the aluminum alloy extrusion material contains 1.80~3.00% by mass of Si, 0.10~1.60% by mass of Mn, 0.01~0.70% by mass of Fe, with the balance being Al and unavoidable impurities; the width of the thinnest part of the cross section perpendicular to the extrusion direction is 0.6 mm or more; after a heating test in which the temperature is raised from 450°C to 575°C for 4~15 minutes and held at 575~615°C for 5~40 minutes, the average grain diameter of the outermost layer of the surface to be bonded is 200 μm or less; and the average grain diameter of the cross section at a depth of 100 μm of the aforementioned thinnest part is 400 μm or more.

[0062] The aluminum alloy extruded material of the present invention is composed of aluminum alloy. That is, the aluminum alloy extruded material of the present invention is an aluminum alloy material and is formed from aluminum alloy.

[0063] The aluminum alloy extruded material of the present invention has a single-layer heat-bonding function. That is, the aluminum alloy extruded material of the present invention can be bonded using the liquid phase generated inside the aluminum alloy material by heating. Therefore, although it is a single layer, it is an aluminum alloy extruded material that can be bonded to other components without using pre-applied brazing filler metal or other bonding materials (hereinafter, it is also described as a single-layer bonded aluminum alloy extruded material). In detail, the aluminum alloy extruded material of the present invention is an aluminum alloy extruded material with a single-layer heat-bonding function at a temperature where the liquid phase fraction is 5.0% or more and 35.0% or less (an aluminum alloy extruded material with a single-layer heat-bonding function).

[0064] Single-layer bonded aluminum alloy extrusions must be bonded at a temperature where the ratio of the mass of the liquid phase generated within the aluminum alloy to the total mass of the aluminum alloy (hereinafter referred to as the "liquid phase ratio") is 5% or more and 35% or less. If the liquid phase ratio exceeds 35%, the amount of liquid phase generated is excessive, and the aluminum alloy cannot maintain its shape, resulting in large deformation. On the other hand, when the liquid phase ratio is less than 5%, bonding becomes difficult. A preferred liquid phase ratio is 5% to 30%, and a more preferred liquid phase ratio is 10% to 20%.

[0065] The formation mechanism of the liquid phase is explained. Figure 1 The diagram schematically illustrates the phase diagram of an Al-Si alloy, a representative binary eutectic alloy. When an aluminum alloy with a Si concentration of c1 is heated, liquid phase formation begins at a temperature T1 near the eutectic temperature (solid line temperature) Te. Below the eutectic temperature Te, as... Figure 2 As shown in (a), the precipitates are distributed within the matrix separated by grain boundaries. Here, if the formation of the liquid phase begins, then as... Figure 2 As shown in (b), the grain boundaries with higher segregation of precipitates melt and become a liquid phase. Then, as... Figure 2 As shown in (c), Si precipitates, which are the main additive element, dispersed in the aluminum alloy matrix, and the periphery of the intermetallic compound melt into spherical shapes to form a liquid phase. Furthermore, as... Figure 2 As shown in (d), the spherical liquid phase generated in the matrix, due to interfacial energy, undergoes resolution in the matrix over time and with increasing temperature, and then migrates towards the grain boundaries and surface through diffusion within the solid phase. Next, as... Figure 1 As shown in the diagram, when the temperature rises to T2, the amount of liquid phase increases according to the phase diagram. Figure 1 As shown, in an aluminum alloy material where the Si concentration is less than the maximum solid solution limit concentration c2, liquid phase formation begins near the solidus temperature Ts2. However, unlike the case of c1, the microstructure before melting is as follows... Figure 3 As shown in (a), sometimes no crystals are present in the matrix. In this case, as... Figure 3As shown in (b), after melting and becoming a liquid phase first occurs at the grain boundaries, as... Figure 3 As shown in (c), a liquid phase is generated in the matrix from regions with locally high solute element concentrations. Figure 3 As shown in (d), the spherical liquid phase generated in the matrix, similar to that in c1, undergoes resolution in the matrix over time and with increasing temperature due to interfacial energy, and then diffuses towards grain boundaries and surfaces through intra-solid diffusion. When the temperature rises to T3, the amount of liquid phase increases according to the phase diagram. Thus, the bonding in this invention utilizes the liquid phase generated by partial melting within the extruded aluminum alloy material through a single-layer bonding process, achieving a balance between bonding and shape maintenance.

[0066] The behavior of the metallographic structure from the generation of the liquid phase to the bonding is explained. A monolayer bonded aluminum alloy extrusion material with a liquid phase generated and an aluminum alloy object material bonded thereto are combined and heated at a temperature where the liquid phase content is 5.0% or more and 35.0% or less. Then, when the bonding area is observed under a microscope, as mentioned above, there is a very small amount of liquid phase embedded on the surface of the monolayer bonded aluminum alloy extrusion material during bonding, and gaps in the aluminum alloy object material where the oxide coating is destroyed by flux, etc. Next, the liquid phase located near the bonding interface of the two alloy materials gradually moves into the aluminum alloy object material, and simultaneously, the solid α-phase grains of the monolayer bonded aluminum alloy extrusion material in contact with the bonding interface gradually grow into the aluminum alloy object material. On the other hand, the grains of the aluminum alloy object material also gradually grow towards the monolayer bonded aluminum alloy extrusion material side. Then, the bonding occurs when the structure of the monolayer aluminum alloy extrusion material enters the aluminum alloy object material near the bonding interface. Therefore, no metallographic structure other than the monolayer bonded aluminum alloy extrusion material and the aluminum alloy object material is generated at the bonding interface.

[0067] On the other hand, when using a brazing plate coated with filler metal and joining it to an aluminum alloy material via brazing heating, a rounded corner is formed at the joint, revealing a eutectic structure. This results in a joint structure different from that formed when joining a single-layer aluminum alloy extrusion material to an aluminum alloy material via brazing heating. Specifically, when using a brazing plate coated with filler metal and joining it to an aluminum alloy material via brazing heating, the liquid phase filler metal fills the joint, forming a rounded corner, thus creating a eutectic structure at the joint that differs from the surrounding area. Furthermore, in the welding method, localized melting also occurs at the joint, resulting in a metallographic structure different from other areas.

[0068] Therefore, when using a single-layer bonded aluminum alloy extrusion material to heat-bond an aluminum alloy object material, the metallographic structure of the joint is composed only of the metallographic structures of the two bonded components, or the metallographic structure of the two bonded components integrated into one. In this respect, the joint structure is different from that in the case of using a brazing plate covered with filler metal, or in the case based on welding.

[0069] Furthermore, due to this joining behavior, when using a single-layer joined aluminum alloy extrusion material to heat-joint an aluminum alloy workpiece, almost no shape change occurs near the joint after the joining process. That is, when using a single-layer joined aluminum alloy extrusion material to heat-joint an aluminum alloy workpiece, almost no shape change occurs after joining, such as weld beads in welding methods or fillets in brazing methods.

[0070] In this invention, determining the actual liquidus fraction of a single-layer bonded aluminum alloy extrusion material during heating is extremely difficult. Therefore, the liquidus fraction specified in this invention is obtained through equilibrium calculations. Specifically, it is calculated using thermodynamic equilibrium calculation software such as Thermo-Calc (registered trademark) manufactured by Thermo-Calc Software AB, based on the alloy composition and the maximum temperature reached during heating.

[0071] based on Figure 4 The state diagram shown illustrates the relationship between the liquid phase fraction and temperature. Figure 4 It is Figure 1 The image obtained through deformation. Figure 4 In the diagram, the line extending parallel to the horizontal axis through temperature Te (hereinafter referred to as "solid line 1") and the line dividing the boundary with the α phase and extending upward and to the left from the left end of solid line 1 to 660°C on the vertical axis (hereinafter referred to as "solid line 2") both represent solid lines. Additionally, the line extending downward and to the right from 660°C on the vertical axis and connecting with the aforementioned solid line 1 (hereinafter referred to as "liquid line 1") and the line dividing the boundary with (Si + liquid phase) and extending upward and to the right from the point of connection both represent liquid lines.

[0072] Here, we designate point P0 at temperature T2, draw a line passing through P0 and parallel to the horizontal axis of the graph, and designate the intersection with liquidus line 1 as P1 and the intersection with solidus line 2 as P2. The Al-Si alloy with Si concentration C1 exists in a state of coexistence of liquid and solid phases at temperature T2. The Si concentration in the liquid phase is the concentration C at point P1. P1 The Si concentration in this solid phase becomes the concentration C at point P2. P2 Furthermore, the ratio of the mass of the liquid phase at temperature T2 to the total mass, i.e., the liquid phase ratio, becomes the ratio of the length of line segment P0 to P2 to the length of line segment P1 to P2.

[0073] As mentioned above, based on Figure 1 and Figure 4The phase diagram of the binary alloy shown is used to determine the liquidus fraction by plotting the alloy composition and temperature. Similarly, for multi-component systems (ternary or higher), the phase diagram is also plotted based on the alloy composition and temperature, thus allowing the determination of the liquidus fraction even for multi-component systems (ternary or higher). It should be noted that the phase diagram of multi-component systems (ternary or higher) is difficult to... Figure 4 Such a simple XY planar diagram can be used to calculate the liquid phase fraction by computer using Thermo-Calc thermodynamic equilibrium calculation software.

[0074] The joined component combined with the aluminum alloy extrusion material of the present invention is made of aluminum alloy or pure aluminum. That is, the joined component combined with the aluminum alloy extrusion material of the present invention is made of aluminum alloy or pure aluminum. When the aluminum alloy material forming the joined component combined with the aluminum alloy extrusion material of the present invention is made of aluminum alloy, the aluminum alloy material forming the joined component combined with the aluminum alloy extrusion material of the present invention may have the same alloy composition as the aluminum alloy material forming the aluminum alloy extrusion material of the present invention, or it may have a different alloy composition.

[0075] The aluminum alloy forming the aluminum alloy extrusion material of the present invention contains 1.80 to 3.00% by mass of Si, 0.10 to 1.60% by mass of Mn, 0.01 to 0.70% by mass of Fe, with the balance being Al and unavoidable impurities.

[0076] Si is an element that forms an Al-Si liquid phase during heat bonding, which aids in bonding. If the Si content of the aluminum alloy is less than 1.80% by mass, a sufficient amount of liquid phase cannot be formed, resulting in reduced bonding strength. Furthermore, if the Si content exceeds 3.00% by mass, it contains a large amount of elemental Si, which significantly increases tool wear during the aluminum alloy manufacturing process. Therefore, the Si content of the aluminum alloy forming the extruded aluminum alloy material of the present invention is specified to be 1.80 to 3.00% by mass. The lower limit of the Si content of the aluminum alloy forming the extruded aluminum alloy material of the present invention is preferably 2.00% by mass. The upper limit of the Si content of the aluminum alloy forming the extruded aluminum alloy material of the present invention is preferably 2.80% by mass. The Si content can be set to a range formed by combining the above-mentioned upper and lower limits.

[0077] Mn is an element that adjusts the crystal structure of aluminum alloy materials, helping to improve heat-bonding and suppress deformation during heat-bonding. If the Mn content of the aluminum alloy is less than 0.10% by mass, the grain diameter of the present invention cannot be obtained, and the deformation during heat-bonding becomes larger. Furthermore, if the Mn content exceeds 1.60% by mass, the deformation resistance of the aluminum alloy material increases, raising concerns about processing difficulties in the manufacturing process. Therefore, the Mn content of the aluminum alloy forming the extruded aluminum alloy material of the present invention is specified to be 0.10 to 1.60% by mass. The lower limit of the Mn content of the aluminum alloy forming the extruded aluminum alloy material of the present invention is preferably 0.20% by mass, more preferably 0.30% by mass. Furthermore, the upper limit of the Mn content of the aluminum alloy forming the extruded aluminum alloy material of the present invention is preferably 1.40% by mass, more preferably 1.20% by mass, more preferably 1.00% by mass, and more preferably 0.80% by mass. The Mn content can be set within a range formed by combining the above upper and lower limits.

[0078] Fe is an element that helps improve the strength of aluminum alloy materials. If the Fe content of the aluminum alloy is less than 0.01% by mass, it requires the use of extremely high-purity aluminum matrix metal, which increases costs. Furthermore, if the Fe content exceeds 0.70% by mass, Al-Fe-Si compounds are formed, reducing the amount of Si that contributes to liquid phase formation during heat bonding, thereby decreasing heat bonding properties. Therefore, the Fe content of the aluminum alloy forming the aluminum alloy extrusion material of the present invention is specified to be 0.01 to 0.70% by mass. The lower limit of the Fe content of the aluminum alloy forming the aluminum alloy extrusion material of the present invention is preferably 0.05% by mass, more preferably 0.10% by mass, and even more preferably 0.15% by mass. Furthermore, the upper limit of the Fe content of the aluminum alloy forming the aluminum alloy extrusion material of the present invention is preferably 0.60% by mass, more preferably 0.50% by mass, and even more preferably 0.40% by mass. The Fe content can be set within a range formed by combining the above upper and lower limits.

[0079] In the aluminum alloy extruded material of the present invention, the width of the thinnest portion in a cross-section perpendicular to the extrusion direction is 0.6 mm or more. When the width is less than 0.6 mm, the rigidity of the material decreases, and there is concern that the metallographic structure of the present invention cannot be obtained.

[0080] Next, the metallographic structure of the aluminum alloy extrusion material of the present invention will be described.

[0081] In the metallographic structure of the aluminum alloy extruded material of the present invention, the grains are made fine at the bonding surface to improve heat bonding performance, and the grains inside the material are made coarse to suppress deformation during heat bonding. These metallographic structures should ideally be achieved just before the formation of the liquid phase. However, the aforementioned metallographic structures are usually maintained after heat bonding, and therefore can be confirmed by any of the following: a structure after heat bonding, a material subjected to a heat test simulating heat bonding, or a material heated to just before the formation of the liquid phase and then cooled. One method of heat treatment involving immediate cooling just before the formation of the liquid phase is as follows: heating to 580°C to 620°C at an average heating rate of 5 to 100°C / min, holding at 580°C to 620°C for approximately 0 to 20 minutes, and then cooling.

[0082] The aluminum alloy extruded material of the present invention, after undergoing a heating test in which the temperature is raised from 450°C to 575°C for 4 to 15 minutes and held at 575 to 615°C for 5 to 40 minutes, has an average grain diameter of less than 200 μm on the outermost layer of the surface to be joined. The average grain diameter of the outermost layer is measured by taking the surface of the surface to be joined as a depth reference (zero position) in a cross section at a depth of 0 to 10 μm along the surface of the surface to be joined (i.e., a cross section perpendicular to the depth direction at a depth of 0 to 10 μm).

[0083] The average grain diameter of the outermost layer affects the heat-bonding properties during the fabrication of aluminum alloy structures. When the average grain diameter of the outermost layer is greater than 200 μm, the heat-bonding properties during the fabrication of aluminum alloy structures decrease. That is, during heat bonding, an Al-Si liquid phase is generated at the grain boundaries of the surfaces to be bonded. This liquid phase is supplied to the bonding portion via the grain boundaries, thereby filling the bonding portion and solidifying to achieve bonding. However, when the average grain diameter of the outermost layer of the surfaces to be bonded is large, there are fewer grain boundaries, thus reducing the amount of liquid phase supplied to the bonding portion, raising concerns about insufficient bonding. For the above reasons, the average grain diameter of the outermost layer of the surfaces to be bonded is specified to be 200 μm or less. Preferably, the average grain diameter of the outermost layer of the surfaces to be bonded is 180 μm or less, more preferably 160 μm or less, and even more preferably 140 μm or less.

[0084] The aluminum alloy extruded material of the present invention, after undergoing a heating test in which the temperature is raised from 450°C to 575°C for 4 to 15 minutes and held at 575 to 615°C for 5 to 40 minutes, has an average grain diameter of 400 μm or more in a cross-section at a depth of 100 μm in the thinnest part. The average grain diameter of the cross-section at a depth of 100 μm in the thinnest part is measured by taking the surface of the surface to be joined as the depth reference (zero position) in a cross-section at a depth of 100 μm along the surface of the surface to be joined (i.e., a cross-section perpendicular to the depth direction at a depth of 100 μm).

[0085] The average grain diameter of the cross-section at a depth of 100 μm in the thinnest part of the wall affects the deformation during heat bonding. When the average grain diameter of the cross-section at a depth of 100 μm in the thinnest part of the wall is less than 400 μm, the deformation during heat bonding becomes significant. That is, during heat bonding, when an Al-Si liquid phase forms at the grain boundaries, a large amount of grain boundary slip occurs when the average grain diameter is small. Since the thinnest part of the wall has particularly low rigidity, it is greatly affected by this slip, resulting in greater deformation and concerns about not meeting dimensional specifications. Based on the above reasons, the average grain diameter of the cross-section at a depth of 100 μm in the thinnest part of the wall is specified to be 400 μm or more.

[0086] Furthermore, the bonding surface of the aluminum alloy extruded material of the present invention and the thinnest part of the wall thickness can be at the same location or at different locations.

[0087] As an example of the metallographic structure of the aluminum alloy extruded material of the present invention, the microstructure of the thinnest part of the aluminum alloy extruded material to be joined after a heating test simulating heat joining is shown below. Figures 5-7 . Figure 5 It is the microstructure of a cross-section parallel to the extrusion direction and the wall thickness direction. The surfaces near the joints exhibit fine recrystallized structures, while the interior of the material has coarse recrystallized structures. Figure 6 It is the microstructure of a cross-section perpendicular to the depth direction in the outermost layer. It is a fine recrystallized structure, suitable for heat bonding. Figure 7 It is the microstructure of a section perpendicular to the depth direction at a depth of 100 μm. It is a coarse recrystallized structure, which is effective in suppressing deformation during heat bonding.

[0088] It should be noted that the average grain diameter in this invention is the average grain diameter measured according to the intercept method of JIS G 0551.

[0089] Thus, the aluminum alloy extruded material of the present invention has the following metallographic structure: when heated from 450°C to 575°C for 4 to 15 minutes and held at 575 to 615°C for 5 to 40 minutes, the average grain diameter of the outermost layer of the surface supplied for bonding is less than 200 μm, and the average grain diameter of the cross section at a depth of 100 μm in the thinnest part of the wall is more than 400 μm.

[0090] Furthermore, the aluminum alloy extruded material of the present invention has the metallographic structure described above. Therefore, by performing a heat treatment that heats the material to the point of almost forming a liquid phase and then immediately cools it down, for example, by performing a heat treatment that heats the material to 580°C to 620°C at an average heating rate of 5 to 100°C / min and holds it at 580°C to 620°C for about 0 to 20 minutes, and then cools it down, a structure is formed in the heat-bonding process where the average grain diameter of the outermost layer of the surface to be bonded is less than 200 μm and the average grain diameter of the cross section at a depth of 100 μm in the thinnest part of the wall is more than 400 μm. Therefore, it is possible to bond the material in a single layer, resulting in good bonding properties and suppressing deformation during heat-bonding.

[0091] The aluminum alloy material used as one of the joined components in the aluminum alloy structure of the present invention and the aluminum alloy extrusion material of the present invention can be manufactured by appropriate combination of continuous casting, DC casting, extrusion, and rolling methods. Furthermore, the aluminum alloy material and pure aluminum material used as another joined component in the aluminum alloy structure of the present invention can be manufactured by appropriate combination of continuous casting, DC casting, extrusion, and rolling methods. New aluminum matrix metal, recycled aluminum matrix metal, intermediate alloys, and aluminum scrap can be used as casting raw materials.

[0092] The aluminum alloy material used as a joined member in the aluminum alloy structure of the present invention and the method for manufacturing the aluminum alloy extruded material of the present invention are characterized by having the following steps:

[0093] The casting process involves casting ingots containing 1.80–3.00% by mass Si, 0.10–1.60% by mass Mn, 0.01–0.70% by mass Fe, with the balance being Al and unavoidable impurities; and

[0094] In the hot extrusion process, the aforementioned ingot is hot-extruded while the temperature of the ingot is above 400°C and below 550°C, forming a shape in which the width of the thinnest part of the cross section perpendicular to the extrusion direction is 0.6 mm or more.

[0095] Furthermore, in the method for manufacturing the aluminum alloy material used as a joined component in the aluminum alloy structure of the present invention and the aluminum alloy extrusion material of the present invention, a homogenization process may be performed after the aforementioned casting process and before the aforementioned hot extrusion process, wherein the homogenization process involves homogenizing the aforementioned ingot at a temperature below 570°C.

[0096] The casting process involves casting an ingot containing 1.80–3.00% by mass Si, 0.10–1.60% by mass Mn, 0.01–0.70% by mass Fe, with the balance being Al and unavoidable impurities, using methods such as DC casting or continuous casting. The lower limit of the Si content in the ingot is preferably 2.00% by mass, and the upper limit is preferably 2.80% by mass. The lower limit of the Mn content in the ingot is preferably 0.20% by mass, more preferably 0.30% by mass, and the upper limit is preferably 1.40% by mass, more preferably 1.20% by mass, more preferably 1.00% by mass, and more preferably 0.80% by mass. Furthermore, the lower limit of the Fe content in the ingot is preferably 0.05% by mass, more preferably 0.10% by mass, and even more preferably 0.15% by mass. The upper limit of the Fe content in the ingot is preferably 0.60% by mass, more preferably 0.50% by mass, and even more preferably 0.40% by mass. The contents of Si, Mn, and Fe can be set to a range formed by combining the above upper and lower limits.

[0097] After the casting process, a homogenization treatment can be performed, keeping the ingot at a temperature below 570°C, preferably between 450 and 570°C, as needed. The holding time for the homogenization treatment can be appropriately selected, preferably 2 hours or more, more preferably 2 to 24 hours. The homogenization treatment has the effect of eliminating microsegregation in the ingot structure of small billets and thus homogenizing the microstructure. If the homogenization treatment temperature is higher than 570°C, there is a concern that the small billets may partially melt. In addition, if the homogenization treatment time is shorter than 2 hours, the diffusion energy becomes insufficient, and there is a concern that the microsegregation in the ingot structure of small billets may not be eliminated. Furthermore, from a productivity point of view, the homogenization treatment time is preferably within 24 hours.

[0098] The hot extrusion process involves hot extruding an ingot at a temperature of 400°C to 550°C to form a shape in which the width of the narrowest part of the cross-section perpendicular to the extrusion direction is 0.6 mm or more. The hot extrusion temperature is ideally between 400°C and 550°C. If the extrusion temperature is below 400°C, the extrusion pressure becomes high, raising concerns about extrusion difficulties. If the extrusion temperature is above 550°C, the aluminum alloy tube being extruded is prone to cracking defects. Therefore, the extrusion ratio in hot extrusion is preferably 20 to 1000. By maintaining an extrusion ratio of 20 to 1000, the processing strain applied to the surface by hot extrusion becomes sufficient, resulting in the metallographic structure of the present invention. Here, the extrusion ratio refers to the ratio of the cross-sectional area of ​​the extrusion cylinder inserted into the small square billet before extrusion to the cross-sectional area of ​​the extruded material. If the extrusion ratio is less than 20, the processing strain applied by hot extrusion becomes insufficient, raising concerns about obtaining the metallographic structure of the present invention. On the other hand, when the extrusion ratio is greater than 1000, the load during extrusion processing increases, hindering extrudability. The lower limit of the extrusion ratio is preferably 20 or more, more preferably 40 or more, and even more preferably 60 or more.

[0099] Furthermore, the manufacturing method of the aluminum alloy material used as a joined component in the aluminum alloy structure of the present invention and the aluminum alloy extrusion material of the present invention can be exemplified by producing small square billets through continuous casting, DC casting, etc., homogenizing them as needed, and then hot rolling them. As for the hot rolling conditions, it is sufficient to appropriately select conditions that deform the surface of the small square billet to a degree that allows the metallographic structure of the present invention to be obtained.

[0100] The joining method in the manufacture of the aluminum alloy structure of the present invention, and the method for joining the aluminum alloy extruded material of the present invention with other components are described.

[0101] Preferably, bonding is performed at a temperature where the ratio of the mass of the liquid phase generated within the aluminum alloy material to the total mass of the aluminum alloy material (hereinafter referred to as the "liquid phase ratio") is 5% or more and 35% or less. This aluminum alloy material is either an aluminum alloy material used as a bonded component or an aluminum alloy material forming the extruded aluminum alloy material of the present invention. If the liquid phase ratio exceeds 35%, the amount of liquid phase generated is excessive, and the aluminum alloy material becomes unable to maintain its shape, resulting in significant deformation. On the other hand, when the liquid phase ratio is less than 5%, bonding becomes difficult. It should be noted that determining the actual liquid phase ratio during heating is extremely difficult. Therefore, the liquid phase ratio is determined through equilibrium calculations. Specifically, it is calculated using thermodynamic equilibrium calculation software such as Thermo-Calc based on the alloy composition and the highest temperature reached during heating.

[0102] Furthermore, to ensure sufficient filling of the joint with liquid phase, the filling time is also preferably considered, preferably a time of 30 seconds or more but less than 3600 seconds for a liquid phase concentration of 5% or more. More preferably, a time of 60 seconds or more but less than 1800 seconds for a liquid phase concentration of 5% or more ensures more thorough filling and reliable bonding. When the time for a liquid phase concentration of 5% or more is less than 30 seconds, the liquid phase may not be able to fully fill the joint. On the other hand, if it exceeds 3600 seconds, deformation of the aluminum material may occur. It should be noted that in the bonding method of the present invention, the liquid phase only moves near the poles of the joint, therefore the filling time is independent of the size of the joint.

[0103] As a specific example of ideal bonding conditions, a bonding temperature of 580°C to 620°C is set, and the holding time at the bonding temperature is set to approximately 0 to 20 minutes. Furthermore, the average heating rate up to the bonding temperature is 5 to 100°C / minute. Here, a holding time of 0 minutes means that cooling begins immediately after the component reaches the specified bonding temperature. Additionally, to ensure that the metallographic structure of the joint forms the suitable state described later, the heating conditions can be adjusted according to the composition.

[0104] An oxide coating forms on the surface of the aluminum alloy material, which hinders bonding. Therefore, it is necessary to break the oxide coating during bonding. To break the oxide coating, it is preferable to apply flux at least at the bonding area. The flux used is a fluoride-based flux such as KAlF4 or CsAlF4, or a chloride-based flux such as KCl or NaCl, which are used in brazing aluminum alloys. These fluxes melt before forming a liquid phase or before reaching the bonding temperature, reacting with the oxide coating and breaking it down. Furthermore, in this method, bonding is carried out in a non-oxidizing atmosphere such as nitrogen or argon to suppress the formation of the oxide coating. Especially when using fluoride-based fluxes, bonding is preferably carried out in a non-oxidizing gas atmosphere where the oxygen concentration is suppressed to below 250 ppm and the dew point is suppressed to below -25°C.

[0105] The following examples illustrate the present invention in detail, but the present invention is not limited to the examples shown below.

[0106] Example

[0107] (Examples and Comparative Examples)

[0108] Manufacturing of Aluminum Alloy Extruded Materials

[0109] First, ingots with the chemical compositions shown in Table 1 (alloy numbers A1~A7) are cast using DC casting. The ingots are cylindrical with a diameter of 90 mm. Then, the ingots are heated for homogenization. The holding temperature and time during homogenization are maintained at 530°C for 8 hours. After homogenization, the ingots are inserted into a preheated container with a diameter of 97 mm at a temperature of 520°C and hot-extruded into flat strips with a width of 35 mm and a thickness of 3.0 mm. Through this method, aluminum alloy extruded material is obtained.

[0110] [Table 1]

[0111]

[0112] <Simulated grain diameter after heated bonding test>

[0113] Using the same manufacturing method as described above, ingots composed of alloys A1 to A7 as shown in Table 2 are hot-extruded at the extrusion ratio shown in Table 2 to produce aluminum alloy extrusion materials B1 to B5 and C1 to C2 with a width of 35 mm and a thickness of 3.0 mm. Ingots composed of alloy A3 as shown in Table 2 are hot-extruded at the extrusion ratio shown in Table 2 to produce aluminum alloy extrusion material C3 with a width of 60 mm and a thickness of 15 mm.

[0114] Next, a heating test was conducted, heating from 450°C to 575°C over 4–15 minutes, and maintaining the temperature at 575–615°C for 5–40 minutes. After cooling to room temperature, test materials B1–B5 and C1–C3 were obtained after the heating test. Then, the material surfaces parallel to the extrusion and width directions were considered as the bonding surfaces. Cutting was performed at the outermost surface and at a depth of 100 μm from the surface, followed by grinding to adjust the surface. Etching was then performed, and arbitrary fields of view were photographed using a polarizing microscope at 50x magnification. The average grain diameter was determined using the intercept method according to JIS G 0551.

[0115] [Table 2]

[0116]

[0117] As shown in Table 2, test materials B1 to B5 have the average grain diameter specified in this invention. On the other hand, test materials C1 and C2 have low Mn content, therefore, the average grain diameter at a depth of 100 μm is smaller than the range specified in this invention. Therefore, there is concern that deformation during heat bonding may become significant. In addition, test material C3 has a low extrusion ratio, therefore, the average grain diameter of the outermost layer is larger than the range specified in this invention. In aluminum alloy materials with heat bonding function in a single layer, grain boundaries become the supply path for the liquid phase, and the average grain diameter of the outermost layer of test material C3 is very large, therefore, it is speculated that the supply path of liquid phase solder is very small. Therefore, there is concern that the heat bonding performance of test material C3 may be reduced.

[0118] <Evaluation of Heat-Jointing Properties and Resistance to High-Temperature Deformation>

[0119] Materials were prepared using the same manufacturing method as described above, resulting in test materials B1~B5 and test materials C1 and C2.

[0120] In the evaluation of heat-bonded properties, the following methods were used: Figure 8 The test pieces shown (reference numeral 1) underwent an inverted T-shaped bonding test. Each test material was cut into 60mm lengths, and a fluoride-based flux was applied to the bonding surfaces. A 1.0mm thick A3003 aluminum alloy plate (reference numeral 2) was erected at the center of the bonding surface of each test material in the width direction, forming an inverted T-shape, and heat treatment for bonding was performed. The heat treatment conditions were: heating from 450°C to 575°C in 4 minutes, holding at 600°C for 3 minutes, and then cooling to room temperature. The presence or absence of bonding was then confirmed by cross-sectional observation; bonded cases were rated as "pass," and unbonded cases were rated as "fail." The results are shown in Table 3.

[0121] To evaluate high-temperature deformation resistance, a sag test was conducted as follows. Each test material was cut into 130mm lengths, with 100mm protruding horizontally from one end, and then subjected to heat treatment for joining. The heat treatment conditions were: heating from 450°C to 575°C over 6 minutes, holding at 600°C for 3 minutes, and then cooling to room temperature. The sag of each test material was then measured. Sags of less than 2mm were rated as "Acceptable / Excellent," sags exceeding 2mm but less than 5mm as "Acceptable / Good," sags exceeding 5mm but less than 20mm as "Unacceptable / Poor," and sags exceeding 20mm as "Unacceptable / Very Poor." The results are shown in Table 3.

[0122] [Table 3]

[0123]

[0124] Test materials B1 to B5 exhibited good heat-bonding properties and high-temperature deformation resistance. On the other hand, test material C1 had a Si content below the range specified in this invention, resulting in poor heat-bonding properties. Furthermore, test material C2 had a Mn content below the range specified in this invention, leading to an average grain diameter at a depth of 100 μm that was smaller than the range specified in this invention. Consequently, it showed significant deformation after heating and poor high-temperature deformation resistance.

[0125] The above description illustrates examples of the aluminum alloy structure, aluminum alloy extrusion material, and manufacturing method of the present invention based on embodiments. However, the specific manner of the aluminum alloy structure, aluminum alloy extrusion material, and manufacturing method of the present invention is not limited to the embodiments, and appropriate modifications can be made without prejudice to the spirit of the present invention.

Claims

1. An aluminum alloy structural body, characterized in that, It is formed by heating and joining one component made of aluminum alloy to another component made of either aluminum alloy or pure aluminum. The joined component contains 1.80–3.00% by mass Si, 0.10–1.60% by mass Mn, 0.01–0.70% by mass Fe, with the balance being Al and unavoidable impurities. At the junction of the one joined member and the other joined member, the average grain diameter in the outermost layer of the one joined member is less than 200 μm, and the average grain diameter in the cross section at a depth of 100 μm in the thinnest part of the one joined member is greater than 400 μm.

2. An aluminum alloy extrusion material, characterized in that, It is an extruded aluminum alloy material with a single-layer heat-bonding function. The aluminum alloy extruded material contains 1.80~3.00% by mass Si, 0.10~1.60% by mass Mn, 0.01~0.70% by mass Fe, with the balance being Al and unavoidable impurities. The width of the thinnest part of the cross-section perpendicular to the extrusion direction is 0.6 mm or more. After a heating test in which the temperature is raised from 450°C to 575°C over 4 to 15 minutes and held at 575 to 615°C for 5 to 40 minutes, the average grain diameter of the outermost layer of the surface to be bonded is less than 200 μm, and the average grain diameter of the cross section at a depth of 100 μm in the thinnest part of the wall is greater than 400 μm.

3. A method for manufacturing an aluminum alloy extruded material, characterized in that, It is a method for manufacturing the aluminum alloy extruded material according to claim 2, the manufacturing method comprising the following steps: The casting process involves casting ingots containing 1.80–3.00% by mass Si, 0.10–1.60% by mass Mn, 0.01–0.70% by mass Fe, with the balance being Al and unavoidable impurities; and In the hot extrusion process, the ingot is hot-extruded while the temperature of the ingot is above 400°C and below 550°C, forming a shape in which the width of the thinnest part of the cross section perpendicular to the extrusion direction is 0.6 mm or more.

4. The method for manufacturing aluminum alloy extruded material according to claim 3, characterized in that, A homogenization process is provided after the casting process and before the hot extrusion process, wherein the homogenization process involves maintaining the ingot at a temperature below 570°C.

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