CN116024461A

CN116024461A - Method for manufacturing aluminum alloy composite material for heat exchanger

Info

Publication number: CN116024461A
Application number: CN202111254957.5A
Authority: CN
Inventors: 太田直希
Original assignee: UACJ Corp
Current assignee: UACJ Corp
Priority date: 2021-10-27
Filing date: 2021-10-27
Publication date: 2023-04-28

Abstract

The present invention provides a method for manufacturing an aluminum alloy composite material for heat exchangers, which can use a large ingot to manufacture the aluminum alloy composite material with excellent characteristics. A method of manufacturing an aluminum alloy composite material for a heat exchanger, comprising: a step of forming a first material as a raw material of the core material by performing at least melting, casting, and surface cutting; forming a second material as a raw material of the sacrificial anticorrosive material by performing at least melting, casting, hot rolling, and cutting; integrating the overlapped material obtained by overlapping the first material and the second material in the thickness direction by hot cladding rolling, thereby forming a rolled material; and a step of cold rolling, annealing, cutting and winding the rolled material into a coil shape.

Description

Method for manufacturing aluminum alloy composite material for heat exchanger

Technical Field

The present invention relates to a method for producing an aluminum alloy composite material for heat exchangers, which is suitable for pipes of condensers and evaporators of heat exchangers for automobiles.

Background

For example, as shown in fig. 1, an evaporator and a condenser of a heat exchanger for an automobile are manufactured by: a tube 1 through which a refrigerant flows, a corrugated Outer fin 2, and a Header plate 3 are attached, and the attached body is brazed at a temperature of about 600 ℃. Fig. 1, 4, shows fins using a Brazing sheet (Brazing sheet) with a Brazing filler metal. In addition, an aluminum alloy composite material for heat exchangers, in which a brazing filler metal (Al-Si alloy: JIS4045 alloy or the like) is coated (Clad) on one surface (refrigerant side) of a core material (Al-Mn alloy: JIS3003 alloy or the like) and a sacrificial anode material (Al-Zn alloy: JIS7072 alloy or the like) is coated on the other surface (atmosphere side) was used for the tube 1. Pure Al, al-Mn based alloy (JIS 3003 alloy, etc.), etc. are used for the outer fin 2. The header plate 3 uses the same aluminum alloy composite material for heat exchanger as the tube 1. In the Inner fin (Inner fin) 4 using the brazing sheet, an aluminum alloy composite material for heat exchanger coated with a brazing filler metal is used on both sides of the core material.

In recent years, in order to reduce the weight of heat exchangers, it has been demanded to reduce the thickness of components. In such a thinned member, it is also necessary to secure a certain strength and corrosion resistance. Therefore, aluminum alloy composite materials for heat exchangers and the like have been proposed, which contain Cu in the core material or increase the Mn content of the core material.

Disclosure of Invention

Problems to be solved by the invention

In order to improve strength, corrosion resistance and manufacturability, optimization of manufacturing processes has been studied in addition to control of alloy composition. In particular, in order to improve manufacturability, it is necessary to reduce manufacturing steps. There are the following problems: in the case of manufacturing an aluminum alloy composite material for heat exchangers using a large ingot industrially, the characteristics of the object cannot be satisfied.

The present invention has been made in view of the above-described problems, and an object thereof is to provide a technique capable of manufacturing an aluminum alloy composite material for heat exchangers excellent in characteristics using a large ingot.

Solution for solving the problem

The method for producing an aluminum alloy material according to the present invention is a method for producing an aluminum alloy composite material for a heat exchanger, the aluminum alloy composite material comprising: a core material formed of an aluminum alloy containing 0.5 to 1.0 mass% of Si, 0.5 mass% or less of Fe, 0.8 mass% or less of Cu, 0.8 to 1.8 mass% of Mn, 0.2 mass% or less of Ti, 0.1 mass% or less of Mg, 0.5 mass% or less of Zn, and 0.1 mass% or less of Cr; and a sacrificial corrosion inhibitor made of an Al-Zn alloy containing 6.0 mass% or less of Si, 0.5 mass% or less of Fe, 0.1 mass% or less of Cu, 1.5 mass% or less of Mn, 0.1 mass% or less of Mg, and 1.0 to 5.0 mass% or less of Zn, the sacrificial corrosion inhibitor having a thickness of 10 to 30% of the total sheet thickness, the heat exchanger aluminum alloy composite having a layer structure in which the core material and the sacrificial corrosion inhibitor are laminated in the thickness direction, and having a total sheet thickness of 0.100 to 0.400mm, the method for producing the heat exchanger aluminum alloy composite comprising: forming a first material as a raw material of the core material by at least melting, casting, and surface cutting; forming a second material as a raw material of the sacrificial anticorrosive material by performing at least melting, casting, hot rolling, and cutting; integrating the overlapped material obtained by overlapping the first material and the second material in the thickness direction by hot cladding rolling, thereby forming a rolled material; and a step of cold rolling, annealing, cutting and winding the rolled material into a coil shape, wherein the width of the overlapped material before cladding rolling is 900mm or more, and the step ofThe thickness of the overlapped material before cladding rolling is 350mm or more, and the product of the thickness and the length of the overlapped material before cladding rolling is 1.5X10 ⁶ mm ² The above method may further comprise heating the overlapped material at 450 to 500 ℃ for 2 hours or more before the clad-rolling, wherein the temperature of the overlapped material at the start of the clad-rolling is 450 ℃ or more, the temperature of the rolled material at the end of the clad-rolling is 250 to 350 ℃, and the thickness of the rolled material at the end of the clad-rolling is 5.0mm or less.

Effects of the invention

As described above, according to the present invention, an aluminum alloy composite material for heat exchangers excellent in characteristics can be produced using a large ingot.

Drawings

Fig. 1 is a schematic view of a heat exchanger for a condenser.

Fig. 2 is a flowchart showing a process for producing an aluminum alloy composite material for heat exchangers.

Fig. 3 is a schematic view showing the structure of an aluminum alloy composite material for heat exchangers according to an embodiment.

Detailed Description

1. Integral construction of aluminum alloy composite material for heat exchanger

The present invention relates to a method for producing an aluminum alloy composite material for heat exchangers having a sheet thickness of 0.100 to 0.400 mm. When the plate thickness is thicker than the above-described range, even if the properties of the aluminum alloy composite material for heat exchangers are deviated, the problem in use is not likely to occur, and therefore the application of the present invention is not required.

The aluminum alloy composite material for heat exchangers according to one embodiment of the present invention has a sacrificial corrosion-resistant material on one surface side of a core material. The aluminum alloy composite material for a heat exchanger according to one embodiment is assembled to the heat exchanger in a tube (tube) processed state, and the corrosion resistance is improved by disposing a sacrificial corrosion inhibitor on the atmosphere side.

The thickness of the sacrificial anticorrosive material in the aluminum alloy composite material for heat exchangers according to one embodiment of the present invention is 10 to 30% of the total thickness. The thickness of the sacrificial anticorrosive material may be a thickness enough to ensure corrosion resistance, and is usually 10 to 30% of the total thickness as in the present invention.

2. Chemical composition

2.1. Chemical composition of core material

The Si of the core material has an effect of forming fine intermetallic compounds of al—mn—si system and improving strength. By the intermetallic compound, recrystallization behavior in braze heating can be controlled to improve the Erosion (Erosion) resistance of the material. When the content of Si is less than 0.5 mass%, the effect may be reduced, and when the content of Si exceeds 1.0 mass%, the melting point of the alloy may be reduced, and the melting of the brazing filler metal in brazing heating becomes remarkable. By setting the Si content to 0.5 mass% or more and 1.0 mass% or less, the variation in characteristics of the aluminum alloy composite material for heat exchangers in the coil can be reduced.

Industrially, fe of the core material is an inevitable element contained in the aluminum alloy. Fe forms coarse intermetallic compounds during casting, and as the number of intermetallic compounds increases, the number of recrystallized nuclei increases during brazing. Further, when the number of recrystallized nuclei increases during brazing, crystal grains are refined, and corrosion along grain boundaries increases, whereby the brazability decreases. Therefore, the content of Fe is 0.5 mass% or less.

The Cu of the core material improves the strength of the aluminum alloy composite material for heat exchangers. When the Cu content exceeds 0.8 mass%, the melting point thereof decreases, and melting occurs at the time of brazing. Since Cu has a large solid solution limit and is present in the core material in a solid solution, cu is an element that has little influence on the effect of the present invention, i.e., the "reduction of characteristic variation of aluminum alloy composite material for heat exchanger".

Mn of the core material increases strength by dispersion strengthening by forming fine intermetallic compounds in the core material. Mn is an element that coarsens recrystallized grains during brazing and improves brazability. The fine intermetallic compound precipitates in the homogenization after casting and in the Clad (Clad) rolling step, but when a deviation occurs in the distribution thereof, a characteristic deviation of the aluminum alloy composite material for heat exchangers occurs. By setting the Mn content to 0.8 to 1.8 mass%, the distribution variation of the fine intermetallic compound can be reduced.

The Ti of the core material may be contained as a main element of a grain refiner at the time of casting. In order to improve corrosion resistance, ti may be contained. When the Ti content exceeds 0.2 mass%, coarse intermetallic compounds are generated, and formability is lowered.

Mg of the core material is an element that greatly improves strength by a small amount of addition in the case of brazing. When soldering is performed using Flux (Flux), mg reacts with the Flux during the soldering heating, and the effect of the Flux is hindered, so that the solderability is lowered. Therefore, the upper limit of the Mg content is set to 0.10 mass%. The smaller the Mg content, the lower the strength improvement effect, but the reaction with the flux is reduced and the solderability is improved. Therefore, mg is not necessarily contained, and the lower limit of the Mg content is 0 mass%.

In order to secure a potential difference with the sacrificial corrosion inhibitor, the Zn content in the core material may be 0.50 mass% or less.

Cr of the core material is contained in order to control the size of recrystallization occurring during brazing. The upper limit of the Cr content is 0.1 mass%. This is because, when the content of Cr exceeds 0.1 mass%, coarse intermetallic compounds are generated, and formability is lowered.

The content of the elements other than the above in the core material is set to 0.05 mass% or less and 0.15 mass% or less in total.

2.2. Chemical composition of sacrificial corrosion protection material

Si may be added to the sacrificial resist in order to function the sacrificial resist as a solder, and the content of Si is limited to 6.0 mass% or less so as not to impair the sacrificial resist due to excessive flow of the solder by the sacrificial resist. However, when Si is reduced in concentration, the cost increases, and therefore, about 0.05 mass% is a lower limit in industry.

In industry, fe, which is a sacrificial corrosion-resistant material, is an unavoidable element contained in aluminum alloys. The upper limit of the content of Fe is 0.5 mass%.

When the content of Fe exceeds the upper limit, the self-corrosion resistance of the sacrificial corrosion-resistant material may decrease and the life as a sacrificial layer may be shortened. The lower limit of the content of Fe is 0 mass% because the lower limit of the content of Fe is less and the corrosion resistance is better. However, when the concentration of Fe is reduced, the cost increases, and therefore, about 0.05 mass% is a lower limit in industry.

Zn of the sacrificial corrosion inhibitor makes the potential of the sacrificial corrosion inhibitor lower, and imparts the sacrificial corrosion inhibitor effect. The core material may contain Cu, so Cu may diffuse from the core material to the sacrificial corrosion barrier material during brazing. The potential of the sacrificial corrosion inhibitor is increased by the diffused Cu, but the sacrificial corrosion inhibitor can sufficiently exhibit the sacrificial corrosion inhibition effect of the sacrificial corrosion inhibitor by setting the Zn content to 1.0 mass% or more. The potential of the sacrificial anticorrosive material is also increased by Cu contained in the sacrificial anticorrosive material, but the sacrificial anticorrosive effect of the sacrificial anticorrosive material can be sufficiently exhibited by setting the Cu content in the sacrificial anticorrosive material to 0.1 mass% or less. On the other hand, by limiting the content of Zn to 5 mass% or less, the following possibility can be reduced: the corrosion rate becomes too high, and thus the self corrosion resistance of the sacrificial corrosion inhibitor is lowered, and the corrosion resistance of the entire aluminum alloy composite material for heat exchangers is lowered.

In the case where the sacrificial corrosion inhibitor is made to function as a solder, mg reacts with the flux to deteriorate the solderability, and therefore the upper limit of the Mg content in the sacrificial corrosion inhibitor is limited to 0.1 mass%. However, when Mg is reduced in concentration, the cost increases, and therefore, about 0.1 mass% is a lower limit in industry.

The content of elements other than the above elements in the sacrificial anticorrosive material is set to 0.05 mass% or less, respectively, and 0.15 mass% or less in total.

3. Method for manufacturing aluminum alloy composite material

Fig. 2 shows a process of a method for producing an aluminum alloy composite material according to an embodiment of the present invention. The method comprises the following steps: and a step of integrating an aluminum alloy ingot (first material) having a thickness of several hundred mm with a second material prepared by hot rolling or the like by hot cladding rolling. The present invention is to stabilize the quality of a product in clad rolling. In the following description, the second material is also sometimes referred to as a skin material. In the following description, hot rolling performed in manufacturing the skin is described as hot rolling only, and hot rolling performed in integrating the first material and the skin is described as being distinguished from clad rolling.

3.1. Method for manufacturing leather

First, a method for manufacturing a skin material will be described. The skin material is a plate material laminated with a first material as a raw material of the core material, and is a second material as a raw material of a sacrificial corrosion-resistant material such as an al—zn alloy.

Firstly, raw materials such as aluminum, aluminum alloy master alloy, aluminum alloy material and the like are mixed and melted to obtain an aluminum alloy melt. The melting and composition adjustment are performed in two furnaces, a melting furnace and a holding furnace. The molten aluminum alloy prepared in the melting furnace is transferred to a holding furnace, and the molten aluminum alloy is treated to finally adjust the composition.

The temperature of the melt in the melting furnace is set to be in the temperature range of 700 to 850 ℃. In a melting furnace, raw material aluminum and the like are melted to obtain an aluminum alloy melt. The obtained aluminum alloy melt is transferred to a holding furnace, and final composition adjustment and the like are performed.

In the holding furnace, the melt is kept at a temperature near 700 ℃ while dehydrogenation, removal of the material, and the like are performed by using a flux or blowing a gas such as Ar gas. The melt after these treatments was cast, but dehydrogenation treatment and melt treatment were also performed from the holding furnace to the casting machine. The dehydrogenation treatment can be performed by blowing Ar gas so as to disperse as bubbles. In the melt processing, the inclusions in the melt are removed by passing the melt through a ceramic filter.

In addition, al alloy wires containing Ti and B are generally added at a constant rate as a refiner between the holding furnace and the casting machine for miniaturization of the ingot structure. The casting of the skin is performed by DC casting (Direct Chill Casting: direct chill casting). The casting speed of the skin is typically 30-60 mm/min. The casting temperature of the second material as a raw material of the sacrificial anticorrosive material is 660 to 700 ℃.

In order to remove entanglement of oxide on the surface of the ingot of the skin formed by the above casting, the ingot was subjected to surface cutting. The surface cutting amount is set according to the surface state of the ingot as long as it is 3mm or more. The cutting of the beginning and/or ending portion of the casting is sometimes performed before the surface cutting. This is because the structure formed by casting is not stable at the beginning and/or end. Typically the cut length is around 150 mm. In some cases, the header and/or the tail are cut in the hot rolling step without cutting at the stage of the ingot.

The slab ingot was heated by hot rolling, but the temperature was around 480 ℃. The heating to high temperature causes energy waste and also causes oxide film growth on the surface of the ingot. The heating time of the ingot is usually 2 hours or more.

The hot rolling of the skin material can be performed by a conventional method, and cutting is performed after rolling to obtain a skin material having a predetermined plate thickness. The predetermined plate thickness is determined based on the thickness of the ingot of the core material after the surface cutting and the cladding ratio of the skin material (the ratio of the thickness of the skin material to the total plate thickness). As described above, the second material can be formed as a skin material.

Before the skin material (second material) and the ingot of the core material (first material) are stacked, the surface of the skin material may be subjected to a brushing process or a chemical conversion treatment in order to improve the skin adhesion during the compounding. In addition, the skin material may be cut in the width direction and the length direction by a saw before being stacked with the ingot (first material) of the core material.

3.2. Method for manufacturing core material

Next, a method for producing the first material, which is a raw material of the core material, will be described. The method of melt casting the first material may be the same as the above-described skin material, and the casting conditions (temperature, melt treatment, addition of a refiner, mold size, casting speed, etc.) may be adjusted to conditions suitable for the production of the first material. Wherein the width of the mold is set to 900mm or more.

Next, cutting of the beginning and/or ending portion of the casting of the ingot of the first material is performed. The reason for cutting the beginning and/or ending of the casting of the ingot of the first material is the same as for the skin. Here, the length of the cast start and/or end portion of the cut ingot of the first material is usually 150mm or more. Instead of cutting the ingot of the first material, a portion corresponding to the start and/or end of casting may be cut in a clad rolling, cold rolling, slit (Slit) process, or the like. However, when cutting is performed after cladding rolling, scraps of a sheet material in which a skin material and a core material are integrated are formed, and recyclability is greatly reduced, so that it is preferable to cut a start portion and/or an end portion of casting in advance at the stage of casting of the first material.

When homogenizing the ingot of the core material, the temperature of the homogenizing treatment is set to 470 to 510 ℃. This temperature is the same as the heating temperature before cladding rolling described later. The time of the homogenization treatment is not particularly limited, but is preferably 12 hours or less from the viewpoint of economy. Further, the homogenization treatment of the ingot of the core material may not be performed.

Desirably, the homogenization treatment of the ingot of the core material is performed before the surface cutting. This is because, when the homogenization treatment is performed after the surface cutting, the oxide film of the surface cutting face grows due to heating in the homogenization treatment. The upper and lower surfaces of the casting block are subjected to surface cutting of at least 3mm or more. The thickness of the ingot of the core material after the surface cutting is strictly set to control the cladding ratio, and the surface cutting is performed so as to be the thickness. In summary, an ingot (first material) of the core material can be formed.

In order to prevent edge breakage after cladding rolling, surface cutting of the end face of the core material in the width direction of the ingot may be performed. In this case, the width of the ingot of the core material after the surface cutting is 900mm or more. In order to improve the pressure-bonding property in cladding rolling, the ingot of the core material after surface cutting may be brushed or etched with caustic soda or the like.

3.3. Superposition

The first material and the skin material (second material) prepared as described above are stacked in the thickness direction to produce a stacked material. In the subsequent heating step, the first material and the second material are usually fixed by a hoop (ironband) so that the first material and the second material do not deviate from each other. The overlapping material can be welded, or welding and fixation by the iron hoop can be used in combination to replace fixation by the iron hoop.

The dimensions of the overlapped material after lamination are specified in the present invention. The width and length of the overlapped material are the width and length of the first material (the ingot of the core material), and the thickness is the sum of the thicknesses of the first material and the second material. In the case where the width of the overlapped material is less than 900mm, the characteristic variation in the width direction is small because the ingot is small, and the method of the present invention may not be applied. Therefore, in the present invention, the width of the overlapped material is set to 900mm or more. The upper limit of the width of the overlapped material may be set according to specifications of equipment such as a hot rolling mill and a cold rolling mill used for manufacturing the aluminum alloy composite material.

The product of the length and thickness of the overlapped material is set to be 1.5X10 ⁶ mm ² The above. This is because, in the clad-rolling, a temperature difference between the central portion and the end portions in the longitudinal direction occurs, and a deviation occurs, and thus, in the present invention, this occurrence is prevented. In the overlapping material, the product of the length and the thickness is less than 1.5X10 ⁶ mm ² In the case of (2), the temperature difference in the longitudinal direction is not likely to occur, and therefore the present invention may not be applied.

The thickness of the overlapped material is set to be 350mm or more. When the thickness is less than 350mm and the product of the length and the thickness is set to be 1.5X10 ⁶ mm ² In this way, the overlapped material becomes thin and long. In the first few passes of cladding rolling, a Bonding pass (Bonding pass) of lightly pressing the first material and the second material is initially performed in several passes. In this case, when the plate thickness is small, the difference in temperature in the longitudinal direction tends to be large, and the product characteristics tend to be uneven. Therefore, the thickness of the overlapped material needs to be 350mm or more.

The upper limit of the thickness of the overlapped material may be set based on the maximum thickness of the hot rolling mill used for cladding rolling. When overlapping materialsThe product of the length and the thickness is 1.5X10 ⁶ mm ² In the above, the length of the overlapped material is not particularly limited as long as it can be heated, handled and rolled. For example, from the viewpoint of operation, the length of the overlapped material may be 3000mm or more. The upper limit of the length of the overlapped material may be set according to specifications of hot rolling equipment or the like for manufacturing the aluminum alloy composite material.

3.4. Cladding rolling

When forming a rolled sheet in cladding rolling, the overlapped material is heated so as to be a cladding rolling temperature. In the present invention, the heating before cladding rolling is performed at 450 to 500 ℃ for 2 hours or more. This is because, when the heating temperature before cladding is lower than 450 ℃, it is difficult to set the cladding start temperature, which will be described later, to 450 ℃ or higher. The heating of the overlapping material in this temperature domain is done for the following purpose: setting the temperature to be capable of cladding rolling; and precipitating elements that are solid-dissolved during casting as fine intermetallic compounds, thereby improving the brazability and strength. When the heating temperature before cladding is higher than 500 ℃, the precipitation of intermetallic compounds is insufficient, and the amount of solid solution elements increases. Therefore, the intermetallic compound is precipitated during cladding rolling, and thus, the amount of the intermetallic compound varies between the end portions and the central portion in the longitudinal direction and the width direction, and the characteristic varies.

The heating time before cladding rolling is set to be more than 2 hours. After the end of 2 hours, the start of cladding rolling is generally waited in a heated state according to the operation conditions of the equipment after the subsequent steps, and the upper limit of the wait time is about 18 hours. By limiting the heating time in this way, the variation in characteristics due to the variation in heating time can be reduced.

Cladding rolling is carried out on the heated overlapped materials by using a hot cladding rolling machine. The starting temperature of cladding rolling was 450 ℃ or higher. The starting temperature of cladding rolling may be measured at the side or upper surface (skin) or lower surface (skin) of the ingot. The rolling pass of cladding rolling was started within 5 minutes after the rolling start temperature was measured.

If the temperature difference from the completion of heating before cladding rolling to the start of cladding rolling is large, the cooling of the outside of the ingot is increased, and therefore, variation in characteristics is liable to occur. Therefore, the rolling start temperature of cladding rolling was set to 450 ℃ or higher.

Cladding rolling of overlapped material typically includes a rolling pass at a light reduction called a joint pass and a subsequent usual rolling pass. The joint pass is a rolling pass for bonding the skin material to the core material metal. The rough rolling and the finish rolling of the clad rolling may be performed by different rolling mills, or the rough rolling and the finish rolling of the clad rolling may be performed by the same rolling mill.

The finishing temperature of cladding rolling is set to 250-350 ℃. When the finishing temperature of cladding rolling exceeds 350 ℃, the cooling rate of the coil of the rolled sheet after finishing is different at the coil end portion from that at the center portion, and thus a difference in characteristics occurs. Further, by controlling the finishing temperature of cladding rolling to a narrow range of 250 ℃ or higher, variations in characteristics of rolled plates between coils are reduced.

3.5. Cold rolling/annealing

The coil of the rolled sheet obtained by cladding rolling is subjected to several passes of cold rolling, whereby the sheet thickness of the product (aluminum alloy composite material) is set. The number of cold rolling passes may be determined according to the rolling capability of the rolling mill. Tempering is arranged by performing a heat treatment after a pass in the middle of cold rolling. That is, annealing is performed on the coil of the rolled sheet after cladding rolling and before cold rolling, and the coil having a predetermined sheet thickness in the middle of the cold rolling pass. The number of anneals was one. In addition, the annealing conditions may be selected to be the most suitable conditions for each aluminum alloy composite material to be produced, and the conditions (annealing temperature and time) do not affect the effect of the present invention, i.e., the "characteristic variation in the coil to be suppressed".

3.6. Surface treatment

For the purpose of brazability and formability, a coil before annealing and a coil after cold rolling may be subjected to surface treatment. In the present invention, no provision is made for surface treatment. This is because the surface treatment affects the state of the coil surface, but the present invention obtains the effect of the present invention by controlling the metal structure inside the material, and the surface treatment is not relevant to the present invention.

3.7. Slitting process

The cold rolled (annealed) coil is processed into a coil of a predetermined plate width for use in the manufacture of a heat exchanger by slitting. Since it is necessary to precisely perform the fine slitting for obtaining the product coil, a slitting process called rough slitting may be performed before the slitting process. Rough cutting is a process of cutting the width and length of a cold rolled (annealed) coil in accordance with the number and diameter of coils completed by finish cutting.

Slitting is a cutting process that does not affect the effects of the present invention. That is, the present invention obtains the effect of the present invention by controlling the metal structure in the material, and therefore the slitting process may be performed by a conventional method, and the method is not particularly limited.

4. Application method of aluminum alloy composite material

The aluminum alloy composite material for heat exchangers produced in the above manner is used as a refrigerant passage component such as a condenser and an evaporator of an automotive heat exchanger. The plate-shaped aluminum alloy composite material for heat exchangers is subjected to electric resistance welding and bending to form a tube shape. Then, the aluminum alloy composite material for heat exchanger, which is formed into a tube shape, is combined with the fin material and the plate material to form a core shape of the heat exchanger, and then the heat exchanger is integrated by a brazing process. The brazing is performed by a so-called CAB method (controlled atmosphere brazing) in which heating is performed in a non-oxidizing atmosphere using a non-corrosive flux.

Examples (example)

Through the steps shown in fig. 2, an aluminum alloy composite material for heat exchangers having a three-layer structure with the structure of fig. 3 as a target value was produced. The following is a detailed description.

1. Production of a second Material as a raw Material for sacrificial anticorrosive Material

To produce an ingot of an Al-Si (4.5 mass%) -Zn (3.8 mass%) alloy, an aluminum melt was obtained by blending and using a melting furnace. The temperature of the melt was set to 700 to 850 ℃. The obtained melt was transferred to a holding furnace, and casting was started after dross removal and composition and temperature adjustment were performed. The target value of the holding furnace temperature was set to 660 to 700 ℃.

Between the holding furnace and the casting machine, degassing and the de-chucking treatment by the ceramic filter were performed. The casting was performed by vertical semi-continuous casting (so-called DC casting), and a mold having a die size of 500mm in thickness and 1390mm in width was used, to obtain an ingot of about 4.4 tons. The casting temperature is 660-700 ℃, and the casting speed is 50-60 mm/min. The composition of the resulting ingots of the second material is shown in table 1. Sr is added for refining the ingot structure. The content of the element not shown in the table is 0.02 mass% or less.

TABLE 1

	Si	Fe	Cu	Mn	Mg	Zn	Ti
								Leather material	4.49	0.19	0.01	0.77	0.002	3.84	0.007
Core material	0.74	0.20	0.49	1.59	0.003	0.01	0.13
															Unit mass%

Surface cutting was performed after cutting about 200mm from the casting start (bottom) of the ingot and removal. The upper and lower surfaces (thickness direction) of the ingot were subjected to surface cutting of 10mm, and then heated at 480℃for hot rolling. The second material is manufactured by performing hot rolling until the plate thickness set for the compounding step is reached and cutting the plate to a predetermined length.

2. Production of first Material as Material for core Material

To manufacture an ingot of the first material, the aluminum melt is obtained by compounding and using a melting furnace. The temperature of the melt was set to 700 to 850 ℃. The obtained melt was transferred to a holding furnace, and casting was started after dross removal and composition and temperature adjustment were performed. The target value of the temperature of the holding furnace was set at 730 to 770 ℃.

Between the holding furnace and the casting machine, degassing and the de-chucking treatment by the ceramic filter were performed. The addition of an Al-Ti-B alloy was performed for the purpose of refining the structure. Casting was performed by vertical semi-continuous casting (so-called DC casting), and a mold having a thickness of 500mm and a width of 1430mm was used, to obtain an ingot of about 6.9 tons. The casting temperature is set to 700-740 ℃, and the casting speed is set to 40-50 mm/min.

The composition of the resulting ingots is shown in table 1. The content of the element not shown in the table is 0.01 mass% or less. An ingot having a length of 3500mm was produced by cutting from a casting start portion (bottom portion) and a casting end portion (head portion) of the ingot. Then, homogenization treatment was performed at 500 ℃. The minimum holding time for the homogenization treatment was 8 hours. In the heating furnace, the time to reach the homogenization treatment temperature was 13 hours in the portion where the temperature was not likely to rise, and the time to reach the homogenization treatment temperature was 8 hours in the portion where the temperature was likely to rise. The homogenization treatment may be omitted. By performing the homogenization treatment, the characteristics can be stabilized even if the heating time before the subsequent cladding rolling varies.

The thickness of the ingot was 480mm by performing surface cutting of 10mm on the upper and lower surfaces (thickness direction) of the ingot subjected to the homogenization treatment. In addition, in order to prevent breakage of the end face, the end face was subjected to surface cutting of only 6 mm.

3. Superposition

A first material having a length of 3500mm and a width of 1400mm and a thickness of 480mm and a second material having a thickness of 150mm and a length of 3300mm were superimposed in the thickness direction. The overlapped material is fixed by iron hoop. The width of the overlapped material was 1400mm, the thickness was 630mm, and the product of the thickness and the length was 2.205×10 ⁶ mm ² 。

4. Cladding rolling

Next, a rolled sheet is formed by cladding rolling of the overlapped material. Heating at 470-490 ℃ for 5 hours before cladding rolling, placing overlapped materials on a conveying line of a hot rolling mill, and discharging the iron hoop for cladding rolling. The starting temperature of cladding rolling was set to about 455 ℃, and ten lightly reduced joining passes were performed. Then, a coil obtained by winding a plate having a thickness of 2 to 4mm and a width of 1305mm was obtained by performing a usual hot rolling pass. The coil temperature at the end of cladding rolling was 305 ℃.

5. Cold rolling/annealing

After four passes of cold rolling were performed on the coil of the rolled sheet obtained by cladding rolling, the rolled sheet was formed into a sheet having a sheet thickness of 0.27mm, and the sheet was wound to form a coil. Annealing was performed by holding the coil at 360 to 370 ℃ (set to 360 to 380 ℃) for 3 hours. Annealing is performed in a non-oxidizing atmosphere. The thickness was set to 0.2mm by performing one pass cold rolling after annealing. The standard deviation of the sheet thickness at this time was 6.1X10 ^-4 mm。

6. Surface treatment

On the cleaning line, the plate surface was spray-cleaned with a neutral detergent (after cleaning, spray-hot water washing (50 to 70 ℃ C.) was performed, and passed through a drying oven for drying at 105 ℃ C.).

7. Slitting process

Rough cutting and slitting processing are carried out, and after the coil is manufactured, the strip width of the product is finely slit. The precision slitting process uses a Block type knife and a ring pit slitting machine (slit). From each of the rough-cut and slit-cut coils, 20 to 30 coils (coils of the aluminum alloy composite material for heat exchangers of the present invention) cut into the width of the product were obtained.

8. Evaluation results

Samples were collected from the beginning and end of the coil of the aluminum alloy composite material for heat exchanger manufactured as described above, and tensile tests were performed, respectively. The tensile strength of the sample taken from the beginning of the coil was 200MPa, the yield strength was 186MPa, and the elongation was 3.9%. The tensile strength of the sample collected from the end of the coil was 200MPa, the yield strength was 187MPa, and the elongation was 2.7%. From this, it is clear that the aluminum alloy composite material for heat exchangers of the present invention has small variation in characteristics.

The aluminum alloy composite material for heat exchangers of this example was bent to a tubular shape called a rivet type, and then combined with fin materials, plates, and the like, and brazed to produce a condenser. Brazing was performed by heating in a temperature range of 590 to 610 ℃ in nitrogen gas using a fluoride-based non-corrosive flux. In the condenser using any one of the strips, the brazed core is free from leakage, and is durable in terms of strength and corrosion resistance.

Description of the reference numerals

1: a tube; 2: an outer fin; 3: a header plate; 4: inner fins of brazing sheet are used.

Claims

1. A method for producing an aluminum alloy composite material for a heat exchanger, wherein the aluminum alloy composite material for a heat exchanger comprises:

a core material formed of an aluminum alloy containing 0.5 to 1.0 mass% of Si, 0.5 mass% or less of Fe, 0.8 mass% or less of Cu, 0.8 to 1.8 mass% of Mn, 0.2 mass% or less of Ti, 0.1 mass% or less of Mg, 0.5 mass% or less of Zn, and 0.1 mass% or less of Cr; and

a sacrificial corrosion-preventing material formed of an Al-Zn alloy containing 6.0 mass% or less of Si, 0.5 mass% or less of Fe, 0.1 mass% or less of Cu, 1.5 mass% or less of Mn, 0.1 mass% or less of Mg, and 1.0 to 5.0 mass% or less of Zn, the sacrificial corrosion-preventing material having a thickness of 10 to 30% of the total plate thickness,

the aluminum alloy composite material for heat exchangers has a layered structure in which the core material and the sacrificial corrosion preventing material are layered in the thickness direction, has an overall plate thickness of 0.100 to 0.400mm,

the method for manufacturing the aluminum alloy composite material for the heat exchanger comprises the following steps:

forming a first material as a raw material of the core material by at least melting, casting, and surface cutting;

forming a second material as a raw material of the sacrificial anticorrosive material by performing at least melting, casting, hot rolling, and cutting;

integrating the overlapped material obtained by overlapping the first material and the second material in the thickness direction by hot cladding rolling, thereby forming a rolled material; and

a step of cold rolling, annealing, cutting and winding the rolled material into a coil shape,

the width of the overlapped material before the cladding rolling is 900mm or more,

the thickness of the overlapped material before the cladding rolling is 350mm or more,

the product of the thickness and the length of the overlapped material before the cladding rolling is 1.5X10 ⁶ mm ² The above-mentioned steps are carried out,

the overlapped material is heated at 450-500 ℃ for more than 2 hours before the cladding is rolled, the temperature of the overlapped material at the beginning of the cladding is more than 450 ℃, the temperature of the rolled material at the end of the cladding is 250-350 ℃, and the thickness of the rolled material at the end of the cladding is less than 5.0 mm.