JP2013194243A - Aluminum alloy laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy laminate or a laminate after heated equivalently to brazing, capable of thinning a wall thickness in a laminate after heated equivalently to the brazing for an aluminum alloy radiator tube or the like, or in a laminate for an aluminum alloy brazing sheet or the like, and excellent in strength enhancement and erosion resistance.SOLUTION: An aluminum alloy laminate 1 or laminate 1 after heated equivalently to brazing 4 is one formed into a heat exchanger by cladding at least a core aluminum alloy sheet 2 and an aluminum alloy sacrifice anticorrosive material 3, and by blazing 4. The core aluminum alloy sheet 2 comprises a specified component composition of 3000 series, and further a particle size distribution of a specified size of deposit in the core aluminum alloy sheet 2 is controlled to make strength enhancement and erosion resistance excellent.

Description

  The present invention relates to an aluminum alloy laminated plate (hereinafter, aluminum is also referred to as Al) excellent in strength and erosion resistance for an aluminum alloy heat exchanger. Here, the laminate is a laminate in which at least a core material aluminum alloy plate and an aluminum alloy sacrificial anticorrosive material are clad. This laminated board is a material for a heat exchanger that is made into a heat exchanger by brazing. Therefore, when it is simply referred to as an aluminum laminate (or laminate), it refers to an aluminum alloy laminate (also simply referred to as laminate) before brazing or before heat treatment equivalent to brazing.

  In order to reduce the weight of automobile bodies, the application of aluminum alloy materials to heat exchange members is increasing in place of copper alloy materials that have been used conventionally. And as these aluminum alloy materials for heat exchange members, corrosion-resistant aluminum alloy materials made of multilayered laminates (also referred to as clad plates or clad materials) are used.

  When the laminated plate is assembled as a heat exchanger by brazing, an aluminum alloy sacrificial anticorrosive material (plate) on one side of the core material (plate) and an aluminum alloy brazing material (plate) on the other side. Each is configured as a clad laminated sheet (brazing sheet).

  FIG. 3 shows an example of an aluminum alloy automobile heat exchanger (radiator). As shown in FIG. 3, the radiator 100 is generally formed by integrally forming a corrugated aluminum alloy heat radiation fin 112 between a plurality of flat tubular aluminum alloy tubes 111. Both ends of the tube 111 are configured to open into spaces formed by a header 113 and a tank (not shown). In the radiator 100 having such a configuration, the refrigerant having a high temperature passes from the space of one tank through the inside of the tube 111 to the space on the other tank side, and heat exchange is performed at the portions of the tube 111 and the radiation fins 112 so that the temperature decreases. Recirculate the refrigerant again.

  The tube 111 made of this aluminum alloy material is composed of an aluminum alloy brazing sheet 101 whose cross section is shown in FIG. In FIG. 4, a brazing sheet 101 is formed by laminating (cladding) an aluminum alloy sacrificial anode material (also referred to as a skin material) 103 on one side surface of an aluminum alloy core material 102, and an aluminum alloy material on the other side surface of the core material 102. A brazing material 104 is laminated (clad). In FIG. 4, the clad sheet made of aluminum alloy is configured as a laminated plate in which only one aluminum alloy sacrificial anticorrosive material 103 is clad on one surface.

  Such a brazing sheet 101 is formed into a flat tubular shape by a forming roll or the like, and is electro-welded or heated by brazing, whereby the brazing sheet 101 itself is brazed and the tube 111 of FIG. A fluid passage is formed.

  The refrigerant (coolant) of the radiator is mainly composed of a water-soluble medium, and a refrigerant appropriately containing a commercially available rust preventive agent or the like is used. However, there is a problem that when a rust preventive agent or the like deteriorates with time, an acid is generated, and the aluminum alloy material such as the sacrificial material or the core material is easily corroded by these acids. For this reason, it is essential to use an aluminum alloy material having high corrosion resistance against a water-soluble medium.

  Therefore, as an aluminum alloy used for a laminated sheet of a brazing sheet or a clad sheet, the core material 102 is defined in JISH4000 from the viewpoint of corrosion resistance and strength, for example, Al-0.15 mass% Cu-1.1 mass%. An Al—Mn-based (3000-based) alloy such as 3003 having a composition such as Mn is used. In addition, for the skin material 103 that is always in contact with the refrigerant, an Al—Zn system such as 7072 made of a composition of Al-1 mass% Zn, etc., for the purpose of anti-corrosion and high strength by Mg diffusion to the core material 102, or Al—Zn—Mg (7000 series) alloys are used. Further, for the brazing filler metal 104, an Al—Si based (4000 based) alloy such as 4045 having a composition such as Al-10 mass% Si having a low melting point is used.

  The radiator 100 is integrally assembled by brazing using a tube 111 formed using such a brazing sheet 101, a heat dissipation fin 112 subjected to corrugation, and other members. Examples of the brazing method include a flux brazing method and a nocolok brazing method using a non-corrosive flux, and brazing by heating to a high temperature of about 600 ° C.

  In the radiator 100 assembled in this way, in particular in the tube 111, the above-described liquid refrigerant from high temperature to low temperature and from high pressure to normal pressure is always circulated and circulated. That is, since the tube 111 is repeatedly subjected to stress over a long period of time including (in addition to) these repeated internal pressure fluctuations and vibrations of the automobile itself, the tube 111 is required to have strength to withstand these. If the strength is low and fatigue failure occurs, cracks in the tube 111 are generated and propagated, and penetrating the tube 111 causes liquid leakage from the radiator. For this reason, improvement in the strength of the radiator tube is regarded as an important issue.

  Conventionally, various improvements in the strength or fatigue characteristics of the radiator tube have been proposed. Typically, the average crystal grain size of the core material in the aluminum alloy brazing sheet is controlled to improve the fatigue fracture resistance due to repeated bending of the tube 111 = vibration fatigue resistance characteristics under automobile vibration. In addition, specific precipitates (intermetallic compounds) are distributed at the core material side interface near the interface between the core material and the sacrificial material of the brazing sheet after brazing, improving the fatigue properties by increasing the strength of the core material side interface. Some are trying.

  However, all of the proposed core materials of the conventional automobile radiator tube are relatively thick with a plate thickness far exceeding 0.20 mm. On the other hand, the weight of the radiator is reduced by reducing the weight of the automobile for improving the fuel efficiency caused by the global environmental problem. For this reason, further thinning of the radiator tube, that is, the aluminum alloy brazing sheet has been studied.

  When the core material of the radiator tube is relatively thick, the rigidity of the tube itself is relatively high. On the other hand, when the thickness of the radiator tube, mainly a laminated plate such as a brazing sheet, is reduced, the rigidity of the tube itself is lowered. On the other hand, the pressure of the refrigerant used is often set higher than before. Therefore, when the plate thickness of a laminated board such as a brazing sheet is thinned by these synergistic effects, the sensitivity to fatigue failure due to the repeated stress increases, and the fatigue characteristics tend to deteriorate. When such fatigue failure occurs, cracks (cracks) occur in the radiator tube, and when the wall is thinned, such cracks penetrate the tube and lead to leakage of the radiator. More likely, more serious damage.

  In addition, when the thickness of a laminated board such as a brazing sheet is reduced, the erosion phenomenon is a phenomenon in which the brazing material of the Al alloy brazing sheet erodes the core material and reduces the thickness of the core material during the brazing. If this happens, it will be serious damage.

  Various improvement measures have been proposed so far in order to improve the strength or fatigue characteristics of the radiator tube thus thinned, as well as the erosion resistance. A typical example is the control of fine precipitates (intermetallic compounds). For example, in Patent Document 1, although the plate thickness is about 0.25 mm, the intermetallic compound of about 0.02 to 0.2 μm of the core material is contained in a number density of 10 to 2000 / μm 3. And by the action of this intermetallic compound, the strength is improved by dispersion hardening, and the recrystallized grains generated during the brazing heating are made coarse and pancake-like. The core material composition is prevented from changing due to diffusion during brazing by the action of trapping the diffusing element at the interface of the particles.

  Moreover, in patent document 2, while refine | miniaturizing the average crystal grain diameter of a core material to 50 micrometers or less, Al and Mn of the diameter of 0.01-0.1 micrometer (10-100 nm) observed by 60,000 times TEM By restricting the number of compounds containing, the above-mentioned erosion resistance is improved.

Furthermore, in patent document 3, the average value of the equivalent circle diameter observed by TEM 50,000 times in the center part of the rolling face plate thickness of the core material aluminum alloy plate which is less than 0.25 mm is 0.1 to 0.5 μm ( The average number density of precipitates in the range of 100 to 500 nm) is set to 150 pieces / μm ³ or less. This is because there are two types of fatigue failure mechanisms in the fatigue characteristics when the thickness of the brazing sheet is reduced, and crack propagation (speed) is more dominant than the occurrence of cracks due to fatigue failure. This is because Patent Document 3 has found that the generation of cracks is more dominant than the propagation (speed) of cracks (cracks, cracks) due to fatigue failure.

  In other words, the metallurgically effective means for improving fatigue characteristics differ from these two fatigue fracture mechanisms, and the crack propagation (velocity) is different from the occurrence of cracks due to fatigue fracture. When the direction is dominant, the propagation (rate) of this fatigue fracture is the structure of the core aluminum alloy plate of the laminated plate constituting the heat exchanger, that is, the average crystal grain size and relatively fine precipitates. It is said to be greatly influenced by the average number density. On the other hand, when the crack generation is more dominant than the propagation (velocity) of the crack (crack, crack) due to fatigue failure, the ease of crack generation constitutes a heat exchanger. It is said that it is greatly influenced by the structure of the core aluminum alloy plate of the laminated plate, that is, the average crystal grain size and the average number density of relatively coarse dispersed particles.

  In Patent Document 3, among them, the fatigue characteristics in the case where the propagation (speed) of fatigue fracture is more dominant than the occurrence of cracks due to fatigue fracture (crack, crack), the material is used as a heat exchanger material. Controls and regulates the average grain size and the average number density of fine precipitates in the structure of the core material aluminum alloy sheet or the structure of the core material aluminum alloy sheet after heating equivalent to brazing, thereby preventing the propagation of fatigue fracture It suppresses and improves the fatigue life (fatigue characteristics) when the propagation of fatigue fracture is dominant. Incidentally, in this patent document 3, the said precipitate is an intermetallic compound of the elements contained, such as alloy elements, such as Si, Cu, Mn, Ti, Fe, Mg, etc., or between these elements and Al. It is a compound and is a generic term for intermetallic compounds that can be identified from the above size by structural observation, regardless of the forming element (composition).

JP-A-8-246117 JP 2002-126894 A JP 2009-191293 A

  However, there is a demand for a brazing sheet that has a thinner thickness (plate thickness) of less than 0.20 mm as compared with these conventional brazing sheets, and that has high strength and excellent erosion resistance.

  For such a brazing sheet having a thickness of less than 0.17 mm, the structure control of the core material aluminum alloy plate in the prior art, that is, the control and regulation of the average crystal grain size and the number density of fine precipitates The actual situation is that the improvement measures alone cannot meet the required high strength and erosion resistance.

  In view of such a problem, an object of the present invention is to provide an aluminum alloy laminated plate for an aluminum alloy heat exchanger that can increase strength and improve erosion resistance even in a brazing sheet having a thinner core material. is there.

In order to achieve this object, the gist of the aluminum alloy laminate of the present invention is an aluminum alloy laminate that is clad with at least a core aluminum alloy plate and an aluminum alloy sacrificial anticorrosive and is used as a heat exchanger by brazing. The core aluminum alloy plate is, in mass%, Mn: 0.5 to 1.8%, Si: 0.2 to 1.5%, Cu: 0.05 to 1.2%, Ti: 0.00. The content of each of the elements is 0.3 to 0.3%, Fe is regulated to 1.0% or less, Cr: 0.02 to 0.4%, Zr: 0.02 to 0.4%, Ni: 0 0.02 to 0.4% of one or two or more of the aluminum alloy composition consisting of Al and inevitable impurities, and the center of the rolled aluminum plate of the core material aluminum alloy plate. Observed by TEM 10000 times That the particle size distribution of the circle equivalent diameter less deposit 100 nm, and the average number density of the precipitates in the range of circle equivalent diameters 10nm~100nm 30 pieces / [mu] m ³ or more, the range equivalent circle diameter of 10nm~60nm The average number density of the precipitates is 15 / μm ³ or more, and the average number density of the precipitates having a circle equivalent diameter in the range of 10 nm to 40 nm is 1.5 / μm ³ or more.

  Here, it is preferable that the core material aluminum alloy plate in the laminated plate further contains Zn: 0.2 to 1.0%. Moreover, it is preferable that the core material aluminum alloy plate in the laminated plate further regulates Mg to 0.5% by mass or less. Moreover, it is preferable that the thickness of the core material aluminum alloy plate in the laminated plate is less than 0.17 mm. Moreover, it is preferable that the thickness of the laminated plate is less than 0.2 mm.

Further, as the structure after the core material aluminum alloy plate in the laminated plate is subjected to the heat treatment corresponding to the brazing, the average crystal grain size in the rolling direction in the longitudinal section of the core material aluminum alloy plate in the rolling direction is 100. As a particle size distribution of precipitates having an equivalent circle diameter of 100 nm or less observed by a TEM of 10,000 times at the center of the rolled face plate thickness of the core aluminum alloy plate, the equivalent circle diameter is in the range of 10 nm to 100 nm. The average number density of the precipitates is 25 pieces / μm ³ or more, the average number density of the precipitates in the range of the equivalent circle diameter of 10 nm to 60 nm is 10 pieces / μm ³ or more, and the equivalent circle diameter is 10 nm to 40 nm. The average number density of precipitates in the range of 0.1 to 0.5 μm in average diameter with a structure having an average number density of precipitates in the range of 1.2 / μm ³ or more. It is preferable to have a structure whose degree is 80 pieces / μm ³ or less.

  The present inventors have found that a thinner brazing sheet having a core material of less than 0.17 mm is influenced by the particle size distribution of a so-called submicron-size precipitate, which is regulated by the prior art. did. That is, even in the brazing sheet having a thinner core material, the strength and erosion resistance are affected by precipitates having a so-called submicron level, which are regulated by the prior art. And in common. However, the inventors of the present invention, in the brazing sheet having a thinner core material, as in the above-described prior art, generally or simply the density and number of precipitates having a size equivalent to a circle of 100 nm or less in a submicron level. It has been found that there is no significant effect on strength and erosion resistance only by the regulation.

  As a result of further investigations, the present inventors, in the brazing sheet having a thinner core material, contrary to the conventional recognition, precipitates having a submicron level size with a circle equivalent diameter of 100 nm or less. (Hereinafter, also referred to as dispersed particles) has been found to be effective in strength and erosion resistance, and should not be regulated but actively present in the structure.

  In this case, the particle size distribution of dispersed particles having an equivalent circle diameter of 100 nm or less (hereinafter also referred to as finely dispersed particles), that is, the density of each finely dispersed particle at various size levels (particle sizes), It was also found that erosion resistance is greatly affected. In other words, not a general density of dispersed particles having an equivalent circle diameter of 100 nm or less, but a precipitate (dispersed particles) having a circle equivalent diameter in the range of 10 nm to 100 nm, which is further divided into three submicron levels. The density (average number density) of precipitates (dispersed particles) in the range of 10 nm to 60 nm, ie, the particle size distribution of the precipitates (particle size distribution of finely dispersed particles) ) Has a significant effect on strength and erosion resistance.

  In the present invention, unlike the prior art, the number of dispersed particles having an equivalent circle diameter of 100 nm or less is not regulated or regulated, but on the contrary, it is actively present (dispersed). Further, in the present invention, not only that, the finely dispersed particles actively present in a large amount are divided into three stages for each size of precipitates at a level corresponding to a circle equivalent diameter of 100 nm or less. Define the average number density and control its particle size distribution.

  Therefore, in the present invention, the particle size distribution of these finely dispersed particles is controlled within a preferable range, and a large amount is actively present (dispersed) in the structure. By the action of these finely dispersed particles, strength and erosion resistance are increased. Can be improved.

  In the regulation of the general density or number of precipitates having a diameter of 0.01 to 0.1 μm (10 to 100 nm) as in Patent Document 2, the particle size distribution as in the present invention is controlled within a preferable range. A suitable number of precipitates are not present (dispersed) in the structure, and a thinner brazing sheet having a core material of less than 0.17 mm has no significant effect on strength and erosion resistance. In addition, even in the general regulation of the average number density of precipitates in the range of the average equivalent circle diameter in the range of 0.1 to 0.5 μm (100 to 500 nm) as in the above-mentioned Patent Document 3, as in the present invention. The appropriate number of precipitates whose particle size distribution was controlled within a suitable range did not exist (disperse) in the structure, and in a thinner brazing sheet having a core material of less than 0.20 mm, the strength and erosion resistance were increased. has no effect.

It is sectional drawing which shows this invention laminated board. It is sectional drawing which shows the heat exchanger made from aluminum alloy. It is sectional drawing which shows the general heat exchanger made from an aluminum alloy. It is sectional drawing which shows laminated sheets, such as a general brazing sheet.

  The best mode for carrying out the laminate of the present invention, the laminate after brazing equivalent heating (thermal history), and these core aluminum alloy plates will be described with reference to FIGS. FIG. 1 is a cross-sectional view of an aluminum alloy laminated plate for a heat exchanger according to the present invention, and FIG. 2 shows a laminated plate (for automobiles) using the laminated plate (aluminum alloy tube for heat exchanger) of FIG. It is principal part sectional drawing of a radiator tube. 1 and 2 are the same as those shown in FIGS. 4 and 5 described above.

(Laminated board)
The laminated board of the present invention is first manufactured in advance as an aluminum alloy laminated board 1 shown in FIG. 1 before being assembled into a heat exchanger. When the laminated plate 1 is brazed, an aluminum alloy sacrificial anticorrosive material (plate) 3 is clad on one surface of the core material aluminum alloy plate 2, and an aluminum alloy brazing material (plate) 4 is clad on the other surface. Configured as a brazing sheet.

  The core material aluminum alloy plate 2 is made of a 3000 series aluminum alloy having a characteristic structure and composition to be described later. Moreover, as the brazing sheet, on the side that is always in contact with the refrigerant inside the core material 2 (upper side in FIG. 1), as a sacrificial anticorrosive material (sacrificial material, lining material, skin material) 3 described later, For example, an Al-Zn composition 7000 series aluminum alloy is clad. Further, the outer side of the core material 2 (the lower side in FIG. 1) is clad with, for example, an aluminum alloy brazing material 4 such as a 4000 series Al—Si composition.

  The laminated board of the present invention is a three-layer rolled clad material (plate) centering on the core aluminum alloy plate 2 as described above. The thickness of the core material aluminum alloy plate is reduced to 0.08 to 0.16 mm, which is less than 0.17 mm, in order to reduce the weight of the heat exchanger. In this case, the thickness of both the brazing material and the sacrificial anticorrosive material is usually about 20 to 30 μm. However, the coverage varies depending on the thickness of the heat exchanger member used (specification of application), and is not limited to these values.

  However, the thickness of the laminated plate 1 such as a brazing sheet (mainly the thickness of the core aluminum alloy plate) is the key to reducing the weight of the heat exchanger as described above. Therefore, it is preferable that the thickness of the laminated plate is about 0.15 to 0.19 mm less than 0.2 mm, and the core material is a thin plate about 0.08 to 0.16 mm less than 0.17 mm.

  These brazing sheets are hot-rolled with a sacrificial anticorrosive material (plate) or brazing material (plate) superimposed on one side of a homogenized heat-treated core aluminum alloy plate (ingot), then cold-rolled, intermediate Annealing and cold rolling are sequentially performed to produce a sheet such as H14 tempered material. Here, the homogenization heat treatment may be performed before hot rolling.

(Heat exchanger)
The aluminum alloy laminated plate 1 such as a brazing sheet is bent in the width direction by a forming roll or the like, and formed into a flat tube so that the skin material 3 is disposed on the inner surface side of the tube. A flat tubular tube is formed. That is, the flat tubular tube (laminated member) 11 shown in FIG.

  Such a flat tubular tube (laminated member) 11 is a heat exchanger such as the radiator 10 shown in FIG. 2 integrally with other members such as the corrugated radiating fins 12 and the header 13 by brazing. Made (assembled). A portion where the tube (laminated member) 11 and the heat radiation fin 12 are integrated is also referred to as a core of the heat exchanger. At this time, the brazing is performed by heating to a high temperature of 590 to 600 ° C. which is higher than the solidus temperature of the brazing material 4. As this brazing method, a flux brazing method, a noclock brazing method using a non-corrosive flux, etc. are generally used.

  In the heat exchanger of FIG. 2, both ends of the flat tube (laminated member) 11 are open to spaces formed by a header 13 and a tank (not shown). Then, the high-temperature refrigerant is sent from the space on one tank side to the space on the other tank side through the inside of the flat tube 11, heat is exchanged between the tube 11 and the fins 12, and the low-temperature refrigerant is circulated again.

(Core material aluminum alloy sheet structure)
Here, the core material aluminum alloy plate in the laminated plate (before and after the brazing equivalent heating) is made of a 3000 series aluminum alloy composition. In the present invention, in order to enhance the strength and erosion resistance of the core material aluminum alloy sheet, the average grain size in the rolling direction in the longitudinal section of the core material aluminum alloy sheet (only the laminated sheet after brazing equivalent heating is specified). ) And the particle size distribution of precipitates (finely dispersed particles) with a circle equivalent diameter of 100 nm or less, which are observed by a TEM (transmission electron microscope) of 10,000 times at the center of the rolled face plate thickness of the core material aluminum alloy plate To do.

(Crystal grains)
When the average crystal grain size of the core aluminum alloy plate as a laminated plate after brazing equivalent heating or a material laminated plate before assembly (thermal history) is refined, the erosion resistance of the plate is lowered. Therefore, the average crystal grain size in the rolling direction in the longitudinal section of the core material aluminum alloy plate in the laminated plate after brazing equivalent heating is coarsened to 100 μm or more. In order to coarsen the core material aluminum alloy plate in the laminated plate after heating corresponding to brazing in this way, naturally, the average grain size of the core material aluminum alloy plate of the material laminated plate is 70 μm or more, preferably 100 μm or more. It is necessary to prepare in advance. However, even if the average grain size of the core aluminum alloy plate of the material laminate is specified, the laminate after heating equivalent to brazing may have an average grain size depending on the heating conditions such as brazing treatment at the time of manufacturing the heat exchanger. The diameter changes (coarse). For this reason, even if the average crystal grain size of the core aluminum alloy plate is defined at the stage of the material laminate, depending on the heating conditions, there is a possibility that the above-mentioned regulation may be coarsened. Not specified.

  In addition, the crystal grain size said here is the crystal grain size of the rolling direction in the longitudinal cross-section (cross section of the board cut | disconnected along the rolling direction) of the rolling direction. This crystal grain size is 50 times higher after the longitudinal section in the rolling direction of the core material aluminum alloy plate (collected sample) in the raw material laminated plate or the laminated plate after brazing equivalent heating is pretreated by mechanical polishing and electrolytic etching. Observe with an optical microscope. At this time, a straight line is drawn in the rolling direction, and a section length of each crystal grain positioned on the straight line is measured by a cutting method (line intercept method) in which each crystal grain size is measured. This is measured at 10 arbitrary locations, and the average crystal grain size is calculated. At this time, the length of one measurement line is 0.5 mm or more, and three measurement lines per one visual field are observed, and five visual fields are observed per one measurement point. Then, the average crystal grain size measured sequentially for each measurement line is averaged sequentially per field of view (3 measurement lines), per field of view per 1 measurement location, and 10 measurement locations, and the average crystal referred to in the present invention. The particle size.

(Precipitate)
When the core material aluminum alloy plate is assembled (incorporated) into a laminated plate after brazing equivalent heating, whether it is a brazing sheet, it is inevitably heated to a temperature around 600 ° C. during brazing. Even if such a heating history is received, the above-described chemical component composition defined in the present invention does not change. However, the average number density of the precipitates defined in the present invention changes to a smaller number in the laminated plate after the brazing equivalent heating than in the raw material laminated plate due to solid solution or coarsening.

  In the present invention, in order to increase the strength and erosion resistance of the core material (plate), the above-mentioned circle equivalent diameter of the core material aluminum alloy plate in the raw material laminated plate or the laminated plate after brazing equivalent heating is 100 microns or less. Specifies the particle size distribution of precipitates (finely dispersed particles) of a level size. As a result, in the present invention, these submicron-sized precipitates are actively present (dispersed) in the structure while their particle size distribution is controlled within a suitable range, and the dispersed precipitates. Strength and erosion resistance are improved by the action of the object.

  The density of precipitates at these various size levels (particle sizes) has a great influence on strength and erosion resistance. The particle size range of the affected precipitates is a precipitate having a circle equivalent diameter of 100 nm or less, a precipitate having a circle equivalent diameter in the range of 10 nm to 100 nm, a precipitate in the range of 10 nm to 60 nm, and a range of 10 nm to 40 nm. It is a three-stage precipitate.

  Here, the equivalent circle diameter is a well-known rule widely used for specifying the “diameter” in the irregular granular precipitates observed with the TEM. The equivalent circle diameter is a diameter of a circle having the same area as the projected area of the granular precipitate (unit: nm), and is also called a Heywood diameter or a centroid diameter. In the present invention, the size of the precipitate and the particle size distribution are defined by the equivalent circle diameter.

  In the present invention, the particle size distribution of the precipitates of the core material as a heat exchanger member that has received a heating history at a temperature near 600 ° C. at the time of brazing or brazing the raw material is specified. That is, unlike the conventional case, a precipitate having a size equivalent to a circle having a sub-micron level with an equivalent circle diameter of 100 nm or less is not regulated. In this case, in the present invention, the submicron-sized precipitates that are actively present are divided into three stages according to the size of the precipitates at a circle equivalent diameter of 100 nm or less. The average number density at is defined and the particle size distribution is controlled.

  Incidentally, it is also possible to more finely define the particle size distribution of the precipitate having a size of the submicron level in three or more stages. However, for example, even if the particle size distribution is defined more finely in 4 steps or more, the difference in the correlation between the three-step particle size distribution specification defined in the present invention and the improvement in strength and erosion resistance is not. In addition, it only takes time and effort for measurement, and it does not make much sense. On the other hand, it is also possible to define the particle size distribution of precipitates having a size of the submicron level in roughly two steps. However, this does not greatly differ from the method that roughly defines the number density of precipitates having an equivalent circle diameter of 100 nm or less (in one step), and the correlation in terms of improving strength and erosion resistance is impaired. For this reason, there is no guarantee that the strength and erosion resistance can be improved reliably.

More specifically, in the present invention, each density (average number density) of a precipitate having an equivalent circle diameter in the range of 10 nm to 100 nm, a precipitate in the range of 10 nm to 60 nm, and a precipitate in the range of 10 nm to 40 nm is defined. . That is, in the laminated plate after brazing equivalent heating, the core equivalent aluminum alloy plate in this laminated plate has a particle size distribution of precipitates with a circle equivalent diameter of 100 nm or less observed by a TEM of 10,000 times at the center of the rolled face plate thickness. The average number density of precipitates having a circle equivalent diameter in the range of 10 nm to 100 nm is 25 / μm ³ or more, and the average number density of precipitates having a circle equivalent diameter in the range of 10 nm to 60 nm is 10 / μm ³ or more. The average number density of precipitates having a circle-equivalent diameter in the range of 10 nm to 40 nm is 1.2 / μm ³ or more.

  When the average number density of each size of the precipitates of the core material aluminum alloy plate of the laminated plate after brazing equivalent heating is below the lower limit of each specified range, the particle size distribution as in the present invention is within the preferred range. Thus, the controlled amount of precipitates does not exist (disperse) in the structure, and a thinner brazing sheet having a core material of less than 0.17 mm has no effect of improving strength and erosion resistance.

On the other hand, in the present invention, the particle size distribution and the average number density of the precipitates of the core material aluminum alloy plate at the raw material laminated plate stage before receiving the heating history at the time of brazing are defined. This rule is to guarantee the particle size distribution and average number density of the precipitates in the core aluminum alloy sheet structure of the laminated sheet after brazing equivalent heating. Specifically, as the particle size distribution of precipitates having a circle equivalent diameter of 100 nm or less observed by a TEM of 10,000 times at the center of the rolled face plate thickness of the core aluminum alloy plate at the material laminate stage, the equivalent circle diameter is The average number density of precipitates in the range of 10 nm to 100 nm is 30 / μm ³ or more, the average number density of precipitates in the range of circle equivalent diameter of 10 nm to 60 nm is 15 / μm ³ or more, and the circle equivalent diameter is The structure is such that the average number density of precipitates in the range of 10 nm to 40 nm is 1.5 / μm ³ or more.

  When the average number density of each size of the precipitates is lower than the lower limit of each specified range of the core aluminum alloy plate of the laminated plate at the raw material laminated plate stage before receiving the heating history at the time of brazing Therefore, the particle size distribution and average number density of the precipitates in the core aluminum alloy sheet structure of the laminated sheet after brazing equivalent heating cannot be guaranteed. Therefore, an appropriate number of precipitates whose particle size distribution is controlled within a suitable range as in the present invention are not present (dispersed) in the core material aluminum alloy plate structure of the laminated plate after brazing equivalent heating, and the core material is 0.1%. In a thinner brazing sheet of less than 17 mm, the effect of improving strength and erosion resistance is lost.

  These precipitates (finely dispersed particles) are alloy elements such as Si, Cu, Mn, and Ti, or intermetallic compounds of contained elements such as Fe and Mg, and intermetallic compounds of these elements and Al. . In the present invention, the size and the average number density are defined as described above. The precipitate is not dependent on the forming element (composition), and the size and average number density are determined by the crack propagation (velocity). This is because it greatly affects the fatigue fracture resistance in dominant fatigue. Therefore, the precipitate (finely dispersed particles) referred to in the present invention is an intermetallic compound having the above-described composition, and does not depend on the forming element (composition), and can be distinguished from the above-mentioned size by microstructure observation. A generic term for compounds.

The size and average number density of these precipitates are measured by observing the structure in the central part of the rolled face plate thickness with 10 fields of view using a TEM (transmission electron microscope) with a magnification of 10,000 times. This is subjected to image analysis, and the average number density (pieces / μm ³ ) of each precipitate in the range of each equivalent circle diameter, the range of 10 nm to 100 nm, the range of 10 nm to 60 nm, and the range of 10 nm to 40 nm is measured.

(Precipitation particle size distribution, number density control)
Control of the average number density of these defined precipitates (finely dispersed particles) is performed by controlling the number density of precipitates crystallized during the casting process in soaking (homogenizing heat treatment). Incidentally, the number density of the precipitates is controlled by the soaking condition in the above-mentioned prior art, but in the above prior art, the soaking temperature is 500 ° C. or higher and burning does not occur in order to regulate and reduce the precipitates. Such a relatively high temperature.

  On the other hand, in the present invention, finely dispersed particles are precipitated in the core material structure by relatively low temperature soaking (hereinafter also referred to as low temperature soaking) at 350 to 450 ° C. Actively distributed to satisfy. If the soaking temperature is less than 350 ° C., the ingot cannot be homogenized. Conversely, if it exceeds 450 ° C., the finely dispersed particles are reduced and the particle size distribution regulation of the finely dispersed particles cannot be satisfied. The number of finely dispersed particles that improve strength and erosion resistance is insufficient.

  If the ingot homogenization or hot rolling start temperature is insufficient due to the relatively low temperature soaking at 350 to 450 ° C., the temperature of 450 ° C. or more and less than 550 ° C. is followed by this low temperature soaking. It is also possible to perform a soaking treatment for a short time, which is reheated to a short time. At this time, after clad a sacrificial anticorrosive material or brazing material on the core material ingot, a relatively low temperature soaking at 350 to 450 ° C. or reheating at a temperature of 450 ° C. or more and less than 550 ° C. may be performed. . Further, only the core material ingot is preliminarily annealed at a relatively low temperature of 350 to 450 ° C., and then the core material ingot is clad with a sacrificial anticorrosive material or a brazing material, and then the clad plate is subjected to 450 ° C. or more and 550 ° C. It may be reheated to a temperature lower than that, and a short-time soaking (hereinafter, also referred to as high temperature soaking) may be performed.

  Such a clad plate after the heat treatment is hot-rolled by a conventional method, further cold-rolled with appropriate intermediate annealing, tempered (heat-treated), and made into a material laminate (brazing sheet). The

(Aluminum alloy composition)
Hereinafter, the aluminum alloy composition of each member constituting the laminate according to the present invention will be described. First, the core material aluminum alloy plate 2 according to the present invention has a 3000 series aluminum alloy composition as described above. However, the core material aluminum alloy plate of the present invention is not only used as a heat exchanger member such as a tube material and a header material, but also to have the structure of the present invention described later, and in addition to that, formability, brazeability or weldability, strength Various properties such as corrosion resistance are required.

  For this reason, the core material aluminum alloy plate according to the present invention is in mass%, Mn: 0.5 to 1.8%, Si: 0.2 to 1.5%, Cu: 0.05 to 1.2%, Each of Ti: 0.03 to 0.3% and Fe: regulated to 1.0% or less, Cr: 0.02 to 0.4%, Zr: 0.02 to 0.4% Ni: One or two or more of 0.02 to 0.4% are contained, and the balance is made of an aluminum alloy composed of Al and inevitable impurities. In addition,% display of content of each element means the mass% altogether.

  Here, the said aluminum alloy plate may contain Zn: 0.2-1.0% by the mass% further. Moreover, it is preferable to regulate Mg to 0.5 mass% or less.

  Elements other than the above-described Fe, Mg, and the above-described elements are basically impurities. However, from the viewpoint of recycling aluminum alloy sheets, not only high-purity Al bullion but also other aluminum alloy scrap materials, low-purity Al bullion, etc. are used as melting materials. Is mixed. And reducing these elements below the detection limit, for example, increases the cost itself, and a certain amount of allowance is required. Therefore, the content in the range which does not inhibit the object and effect of the present invention is allowed. For example, elements other than the above, such as B, may be contained if they are 0.05% or less.

Si: 0.2 to 1.5%
Si forms an intermetallic compound with Fe to increase the strength of the core aluminum alloy plate. For this reason, in order to ensure the required intensity | strength as a laminated board after the said laminated board and brazing equivalent heating, a lower limit is contained 0.2% or more. On the other hand, if the Si content is too high, a coarse compound is formed in the core material, and the recrystallized grains during brazing and heating annealing are made smaller, so that diffusion of brazing into the core material during brazing is promoted. The brazing performance of the laminated plate during brazing heating is reduced. Moreover, the diffusion of Si during brazing heating increases, and the corrosion resistance of the laminated plate and the laminated plate after brazing equivalent heating is lowered. Therefore, the upper limit is 1.5% or less. Therefore, the Si content range is set to 0.2 to 1.5%.

Cu: 0.05-1.2%
Cu exists in the aluminum alloy plate in a solid solution state, and improves the strength of the core material aluminum alloy plate. In addition, the potential in the core material is made noble and corrosion resistance is improved. For this reason, in order to ensure the required intensity | strength as a laminated board after the said laminated board and brazing equivalent heating, a lower limit is made 0.05% or more. On the other hand, if the Cu content is too large, a coarse Cu-based compound precipitates at the grain boundaries during cooling after brazing heating, and intergranular corrosion is likely to occur, and the corrosion resistance is lowered. The following. Therefore, the Cu content range is 0.05 to 1.2%.

Mn: 0.3 to 1.8%
Mn is an element for improving the strength without distributing the defined finely dispersed particles in the aluminum alloy plate and reducing the corrosion resistance of the core aluminum alloy plate. It also has the effect of enhancing vibration fatigue resistance and fatigue fracture resistance. For this reason, in order to ensure the required strength as the laminated board or the laminated board after brazing equivalent heating and to improve the fatigue fracture resistance, the lower limit is 0.3% or more.

  On the other hand, if the Mn content is too large, the number density of coarse compounds increases, and conversely, the number density of precipitates in each specified particle size becomes too smaller than specified, and vibration fatigue resistance and fatigue fracture resistance are reduced. Let Further, the increase in the number density of coarse compounds reduces the formability of the aluminum alloy laminate, and the aluminum alloy laminate may be broken during processing such as assembly to a part shape. For this reason, the upper limit of the Mn content is 1.8% or less. Therefore, the content range of Mn is made 0.3 to 1.8%.

Ti: 0.03-0.3%
Ti has the function of forming a fine intermetallic compound in the aluminum alloy plate and improving the corrosion resistance of the core aluminum alloy plate. For this reason, in order to ensure the required corrosion resistance as the laminated board or the laminated board after brazing equivalent heating, the lower limit is made 0.03% or more. On the other hand, if the Ti content is too high, the number density of coarse compounds increases, the formability of the aluminum alloy laminate decreases, and the aluminum alloy laminate may break during processing such as assembly to a part shape. There is. For this reason, the upper limit of Ti content is made 0.3% or less. Therefore, the Ti content range is 0.03 to 0.3%.

Fe: 1.0% or less (including 0%)
As long as scrap is used as an aluminum alloy melting raw material as an impurity, Fe is inevitably contained in the core aluminum alloy plate. Fe has the effect of increasing the strength of the core material aluminum alloy plate and increasing the brazing property of the core material by forming an intermetallic compound with Si as described above. However, if the content is too high, a coarse compound is formed in the core material to reduce the recrystallized grains during brazing and heating annealing, and therefore to promote the diffusion of brazing into the core material during brazing. Since the brazing performance of the laminated plate during brazing heating is significantly reduced, the Fe content is restricted to 1.0% or less (including 0%).

Mg: 0.5% or less Mg has an effect of increasing the strength of the core aluminum alloy plate, but if its content is large, brazing performance is significantly lowered in a Nocolok brazing method using a fluoride flux. For this reason, it is preferable to regulate the Mg content to 0.5% or less for a heat exchanger under brazing conditions in which the brazing property is lowered by Mg.

One or more of Cr: 0.02-0.4%, Zr: 0.02-0.4%, Ni: 0.02-0.4% Cr, Zr, Ni are specified It is an element for distributing precipitates (intermetallic compounds) having a size equivalent to a circle and having a submicron level with an equivalent circle diameter of 100 nm or less in an aluminum alloy plate. Among these, especially Zr has the greatest effect of distributing finely dispersed particles in the aluminum alloy plate by a specified particle size distribution. If Cr, Zr, and Ni are less than the specified lower limit amounts, the finely dispersed particles cannot be sufficiently distributed, and the strength and erosion resistance cannot be improved. On the other hand, if the amount of Cr, Zr, and Ni exceeds the specified upper limit amounts, the dispersed particles (precipitates) become coarse, and on the contrary, strength, erosion resistance, fatigue fracture resistance, and the like are inhibited.

Zn: 0.2-1.0%
Zn has the effect of improving the vibration fatigue resistance of the core aluminum alloy plate and the fatigue characteristics in fatigue where crack propagation is dominant. However, since Zn has the action of preferentially corroding the base phase potential, if the Zn content in the core material is large, the potential difference between the sacrificial anticorrosive material provided as the preferential corrosion layer and the core material becomes small. Corrosion resistance deteriorates. Therefore, the Zn content is preferably in the range of 0.2 to 1.0%.

(Brazing alloy)
As the brazing material alloy 4 clad on the core material aluminum alloy plate 2, a known brazing material aluminum alloy such as a 4000 series Al—Si based brazing material such as JIS4043, 4045, 4047 which has been widely used in the past can be used. The brazing material alloy is configured as a brazing sheet in which an aluminum alloy sacrificial anticorrosive material (plate) 3 is clad on one surface and an aluminum alloy brazing material (plate) 4 is clad on the other surface.

(Sacrificial anticorrosive material)
The sacrificial anticorrosive material alloy 3 clad on the core aluminum alloy plate 2 is a known sacrificial anticorrosive material aluminum alloy containing Zn, such as a 7000 series aluminum alloy such as JIS7072 of Al-1 mass% Zn composition that has been widely used conventionally. Can be used. Such a sacrificial anticorrosive material is essential for a heat exchanger for automobiles in which cooling water is present on the inner surface side of the tube. That is, it is indispensable for preventing corrosion and ensuring corrosion resistance on the inner surface of the tube where the cooling water is present.

  Hereinafter, the present invention will be described more specifically with reference to examples. A laminate (brazing sheet) 1 having a 3000 series aluminum alloy core material 2 having the composition of A to T shown in Table 1 was prepared, and the structure of the core material 2 portion was examined. Further, the laminated plate 1 was heated and held at a temperature of 600 ° C. for 3 minutes, imitating brazing, and then cooled at an average cooling rate of 100 ° C./min. The structure of the core part of the later laminate was investigated. These results are shown in Table 2. In addition, the mechanical properties and erosion resistance of the laminate after the brazing equivalent heating were measured and evaluated. These results are shown in Table 3.

(Manufacture of laminates)
The production of the laminate was as follows. A 3000 series aluminum alloy composition having the composition of A to T shown in Table 1 was melted and cast to prepare an aluminum alloy core material ingot. In the invention example, only this core material ingot was subjected to a soaking treatment that was held for 10 hours in common at a low temperature under the temperature conditions shown in Table 2. Thereafter, after the sacrificial anticorrosive material and the brazing material were laminated, they were reheated and subjected to a second soaking process at a higher temperature (3 hours in common) to control the particle size distribution of the precipitates. The “low temperature soaking temperature” shown in Table 2 is the soaking temperature of only the core material ingot, and the “second soaking temperature” is the soaking temperature of the laminate (laminated ingot).

  Lamination to the core material ingot 2 is composed of a JIS7072 aluminum alloy plate made of Al-1 mass% Zn composition on one surface of the core material ingot 2 as a sacrificial anticorrosive material and an Al-10 mass% Si composition on the other surface. Each JIS 4045 aluminum alloy plate was clad as a brazing material. Then, hot rolling was started at the second soaking temperature. At this time, the time from the end of the second soaking process to the start of hot rolling was kept constant at 30 minutes. Further, by appropriately combining cold rolling and finish annealing, the thickness of the core aluminum alloy plate is reduced to 0.11 mm which is less than 0.17 mm, and a laminated plate (brazing sheet) as an H24 tempered material is obtained. . In common with each example, the thickness of the laminated plate (brazing sheet) is 0.11 mm of the core material aluminum alloy plate, and the thickness of both the brazing material and the sacrificial anticorrosive material laminated on each surface of the core material. The thickness ranged from 25 to 35 μm.

(Organization)
Using each of the measurement methods described above, the structure of the core material portion of the laminated plate, which is the cold-rolled clad plate, and the core material portion of each laminated plate after the heating is observed, and the rolling direction in the longitudinal section in the rolling direction is observed. The average crystal grain size (μm) and the average number density (pieces / μm ³ ) of precipitates with equivalent circle diameters in the specified ranges as observed by a TEM of 10,000 times at the center of the rolled face plate thickness were measured. These results are shown in Table 2. In addition, regarding the average number density of the precipitates, the thickness of the sample at the observation site was obtained using equal thickness interference fringes, and the number of precipitates per unit volume of the sample was measured. Here, although the average crystal grain size of the core material aluminum alloy plate of the laminated plate before brazing equivalent heating as the material is not shown in Table 2, the tempered material by rolling has a processed structure, Since evaluation was difficult with an optical microscope, it was not evaluated here.

(Mechanical properties)
A tensile test of each laminated board after the heating was performed, and tensile strength (MPa), 0.2% proof stress (MPa), and elongation (%) were measured. These results are shown in Table 3. As test conditions, JISZ2201 No. 5 test piece (25 mm × 50 mmGL × plate thickness) perpendicular to the rolling direction was sampled from each laminated plate and subjected to a tensile test. The tensile test was conducted at room temperature of 20 ° C. based on JISZ2241 (1980) (metal material tensile test method). The crosshead speed was 5 mm / min, and the test was performed at a constant speed until the test piece broke.

(Erosion resistance)
The erosion resistance was evaluated by measuring the erosion depth. The produced brazing sheet was subjected to 10% rolling and held at 600 ° C. for 5 minutes or more in an atmosphere having an oxygen concentration of 200 ppm or less to produce a brazed test piece. The cross section parallel to the rolling direction of the brazing sheet after brazing was observed with an optical microscope, and the erosion depth of the brazing material into the core material, that is, the erosion depth (μm) was measured. The observation magnification with an optical microscope is 100 times, and in the part where the grain boundary on the brazing filler metal side in the visual field is eroding into the core material, the depth is measured and averaged, and then the measurement is performed with 10 visual fields. The value was the erosion depth.

As shown in Tables 1 and 2, Invention Examples 1 to 13 perform low-temperature soaking and high-temperature soaking in the core material aluminum alloy plate (ingot) within the composition range of the present invention and in a preferable soaking condition range. (Invention example 3 is only low-temperature soaking and not high-temperature soaking). For this reason, as shown in Table 2, the core material aluminum alloy plate of the laminated plate (brazing sheet) has a structure in which the particle size distribution of the defined precipitate is within the specified range. That is, as the particle size distribution of precipitates with a circle equivalent diameter of 100 nm or less observed by a 10000 times TEM at the center of the rolled face plate thickness of the core aluminum alloy plate, the average of the precipitates with a circle equivalent diameter in the range of 10 nm to 100 nm Precipitates having a number density of 30 / μm ³ or more and an average number density of precipitates having a circle equivalent diameter in the range of 10 nm to 60 nm of 15 pieces / μm ³ or more and a circle equivalent diameter in the range of 10 nm to 40 nm. The average number density is 1.5 / μm ³ or more. Further, the average crystal grain size in the rolling direction in the longitudinal section in the rolling direction of the core aluminum alloy plate in the laminated plate after the brazing equivalent heating is also coarsened to 100 μm or more.

  As a result, in the inventive examples 1 to 13, even if the core material is thinned to 0.11 mm, which is less than 0.17 mm, the laminated plate after brazing equivalent heating has a predetermined strength, and the erosion depth is It is 50 μm or less and excellent in erosion resistance. That is, it can be seen that even a thinner brazing sheet can increase the strength and improve the erosion resistance.

  However, among Invention Examples, Invention Example 11 using Alloy Examples J and K in Table 1 in which the Mg content of the core aluminum alloy plate (ingot) is relatively high at 0.5% and 0.8%, Although 12 is not shown in the test results, the brazing performance is significantly lowered when the Nocolok brazing method using a fluoride-based flux is used. For this reason, as described above, it is preferable to regulate the Mg content to 0.5% or less for a heat exchanger under brazing conditions in which brazing properties are lowered by Mg.

In contrast, in Comparative Examples 14 to 16, the core material aluminum alloy plate (ingot) is within the composition range (B) of the present invention, but the soaking conditions of the low temperature soaking are outside the preferred range. For this reason, as shown in Table 2, the core material aluminum alloy plate of the laminated plate does not satisfy the particle size distribution of the precipitates defined in the present invention, and the average number density of the 10 nm to 100 nm precipitates is less than 30 / μm ^3. Alternatively, the average number density of precipitates of 10 nm to 60 nm is less than 15 / μm ^3, or the average number density of precipitates of 10 nm to 40 nm is less than 1.5 / μm ³ . Further, the average crystal grain size in the rolling direction in the longitudinal section in the rolling direction of the core material aluminum alloy plate in the laminated plate after the brazing equivalent heating is not coarsened to 100 μm or more. As a result, as shown in Table 2, the laminates after the brazing equivalent heating of Comparative Examples 14 to 16 have low strength, the erosion depth exceeds 50 μm, and the erosion resistance is poor.

  In Comparative Examples 14 and 16, the second high-temperature soaking temperature is appropriate, but the first low-temperature soaking is not performed. In Comparative Example 16, the second soaking temperature is the same as the conventional temperature level, and the temperature is too high. In Comparative Example 15, the temperature of the first low temperature soaking is as low as 300 ° C.

Although Comparative Examples 17-24 are manufactured under preferable soaking conditions (except for Comparative Example 23), the component compositions M, N, O, P, and Q in which the core material aluminum alloy plate (ingot) deviates from the scope of the present invention. , R, S, T (Table 1). For this reason, the particle size distribution of the precipitates defined in the present invention is not satisfied, and the average number density of precipitates of 10 nm to 100 nm is less than 30 / μm ^3, or the average number density of precipitates of 10 nm to 60 nm is 15 pieces / [mu] m ³ than either the average number density precipitates the range of the 10nm~40nm is less than 1.5 / [mu] m ^3. Further, the average crystal grain size in the rolling direction in the longitudinal section in the rolling direction of the core material aluminum alloy plate in the laminated plate after the brazing equivalent heating is not coarsened to 100 μm or more. As a result, as shown in Table 2, the laminates after the brazing equivalent heating of Comparative Examples 17 to 24 have low strength and inferior erosion resistance.

In Comparative Example 17, the amount of Si is too small, as in alloy abbreviation M in Table 1.
In Comparative Example 18, the amount of Cu is too small as in the alloy abbreviation N in Table 1.
In Comparative Example 19, the amount of Mn is too small like the alloy abbreviation O in Table 1.
In Comparative Example 20, the amount of Fe is too large as in the alloy abbreviation P in Table 1.
In Comparative Example 21, the amount of Ti is too small, as in alloy abbreviation Q in Table 1.
Comparative Examples 22 and 23 do not contain Cr, Zr, or Ni as in alloy abbreviations R and S in Table 1. In Comparative Example 23, the first low-temperature soaking temperature is too high at 480 ° C.
In Comparative Example 24, the amount of Zn is too large, as in alloy abbreviation T in Table 1.

  Therefore, from the results of the above examples, the critical significance or effect of each requirement of the present invention for excellent mechanical properties as a heat exchanger laminated plate or a laminated plate after brazing equivalent heating is supported. It is done.

  According to the present invention, it is possible to increase the strength and improve the erosion resistance even in a brazing sheet in which the core material is thinner than 0.2 mm. Therefore, it is possible to reduce the thickness of a laminated plate after brazing equivalent heating such as an aluminum alloy radiator tube or a laminated plate such as an aluminum alloy brazing sheet, and to improve the strength and erosion resistance. The laminated board after brazing equivalent heating can be provided. For this reason, the present invention is suitable for use in aluminum alloy heat exchangers for automobiles and the like that are required to have excellent fatigue characteristics as well as thin radiator tubes.

1: Aluminum alloy laminated plate for heat exchanger, 2: Core material, 3: Skin material, 4: Brazing material, 10: Radiator (heat exchanger), 11: Tube (laminated member), 12: Radiation fin, 13: Header

Claims (6)

At least a core material aluminum alloy plate and an aluminum alloy sacrificial anticorrosive material are clad, and are made into a heat exchanger by brazing, wherein the core material aluminum alloy plate is in mass%, and Mn: 0.5 to 1.8%, Si: 0.2 to 1.5%, Cu: 0.05 to 1.2%, Ti: 0.03 to 0.3%, respectively, and Fe: 1.0% or less And further containing one or more of Cr: 0.02-0.4%, Zr: 0.02-0.4%, Ni: 0.02-0.4% Further, the balance has an aluminum alloy composition composed of Al and inevitable impurities, and further, a precipitate having an equivalent circle diameter of 100 nm or less observed by a TEM of 10,000 times at the center of the rolled face plate thickness of the core aluminum alloy plate Circle equivalent diameter as particle size distribution The average number density of precipitates in the range of 10 nm to 100 nm is 30 / μm ³ or more, and the average number density of precipitates in the range of equivalent circle diameter of 10 nm to 60 nm is 15 / μm ³ or more, An aluminum alloy laminate, wherein an average number density of precipitates having an equivalent diameter in the range of 10 nm to 40 nm is 1.5 / μm ³ or more.   The aluminum alloy laminated plate according to claim 1, wherein the core material aluminum alloy plate in the laminated plate further contains Zn: 0.2 to 1.0%.   The aluminum alloy laminated plate according to claim 1 or 2, wherein the core material aluminum alloy plate in the laminated plate further regulates Mg to 0.5% or less.   The aluminum alloy laminate according to any one of claims 1 to 3, wherein a thickness of the core aluminum alloy plate in the laminate is a thin wall having a thickness of less than 0.17 mm.   The aluminum alloy laminated plate according to any one of claims 1 to 4, wherein the laminated plate has a thickness of less than 0.2 mm. As the structure after the core aluminum alloy plate in the laminated plate is subjected to the heat treatment corresponding to the brazing, the average crystal grain size in the rolling direction in the longitudinal section of the core aluminum alloy plate in the rolling direction is 100 to 200 μm. In addition, as a particle size distribution of precipitates having an equivalent circle diameter of 100 nm or less observed by a TEM of 10,000 times at the center of the rolled face plate thickness of the core aluminum alloy plate, precipitation with an equivalent circle diameter in the range of 10 nm to 100 nm The average number density of objects is 25 pieces / μm ³ or more, the average number density of precipitates in the range of circle equivalent diameter of 10 nm to 60 nm is 10 pieces / μm ³ or more, and the circle equivalent diameter is in the range of 10 nm to 40 nm. aluminum alloy laminate according to any one of claims 1 to 5 mean number density of precipitates having a tissue is 1.2 pieces / [mu] m ³ or more

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