CN115722830A - Method for manufacturing aluminum alloy composite material for brazing - Google Patents

Abstract

The present invention relates to a method for producing an aluminum alloy composite material for brazing, which can improve the yield after clad rolling and reduce the amount of clad chips generated. A method of manufacturing an aluminum alloy composite material for brazing, comprising: a step of forming a first material as a raw material of a core material by performing at least melting, casting, and surface cutting; a step of forming a second material as a raw material of the brazing filler metal by performing at least melting, casting, hot rolling, and cutting; and integrating a superimposed material obtained by superimposing the first material and the second material in the thickness direction by hot cladding, wherein the width of the second material is smaller than the width of the first material by only 0 to 50mm at the start of cladding.

Description

Method for manufacturing aluminum alloy composite material for brazing

Technical Field

The present invention relates to a method for producing an aluminum alloy composite material for brazing suitable for a plate material of a radiator, an evaporator, or the like of an automobile heat exchanger.

Background

For example, as shown in fig. 1, a radiator of a heat exchanger for an automobile is manufactured by: the tube 1 through which the refrigerant flows, the corrugated fin 2, and the Header plate 3 are attached, and the attached body is brazed at a temperature of about 600 ℃. The tank for collecting refrigerant is shown at 4 in fig. 1. An aluminum alloy composite material for brazing, in which a brazing filler metal (Al-Si alloy: JIS4045 alloy or the like) is coated (Clad) on one surface (air 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 (refrigerant side), is used for the pipe 1. Pure Al, al-Mn alloy (JIS 3003 alloy, etc.) and the like are used for the fin 2. The same brazing aluminum alloy composite material as that for the tube 1 is used for the header plate 3.

Disclosure of Invention

Problems to be solved by the invention

In an automotive heat exchanger, a Clad (Clad) material is generally used in order to satisfy various properties such as thermal conductivity, durability, corrosion resistance, and brazeability, but there is a problem that the yield in producing the Clad material is low. In addition, since it is difficult to effectively use the chips of the clad material, it is necessary to improve the yield in manufacturing.

The present invention has been made in view of the above problems, and an object thereof is to provide a method for producing a clad material that improves the yield after cladding rolling and reduces the amount of clad scrap generated.

Means for solving the problems

The method for producing an aluminum alloy material of the present invention is a method for producing an aluminum alloy composite material for brazing, the aluminum alloy composite material for brazing comprising: a core material made of an aluminum alloy containing 0.2 to 0.7 mass% of Si, 0.7 mass% or less of Fe, 0.1 to 0.8 mass% of Cu, and 0.7 to 2.0 mass% of Mn, with the remainder being composed of unavoidable impurities and Al; and a brazing filler metal formed of an aluminum alloy containing 6 to 13 mass% of Si and 0.8 mass% or less of Fe, with the remainder being composed of unavoidable impurities and Al, the brazing filler metal being coated on at least one surface of the core material so that a coating ratio of the brazing filler metal is 1 to 20%, the method for producing the aluminum alloy composite material for brazing including: forming a first material as a raw material of the core material by performing at least melting, casting, and surface cutting; a step of forming a second material as a raw material of the brazing filler metal by performing at least melting, casting, hot rolling, and cutting; and integrating a superimposed material obtained by superimposing the first material and the second material in the thickness direction by hot cladding, wherein the width of the second material is smaller than the width of the first material by only 0 to 50mm at the start of cladding.

Effects of the invention

According to the present invention, the yield after clad rolling can be improved and the amount of clad chips generated can be reduced.

Drawings

FIG. 1 is a schematic diagram of a heat exchanger for a radiator.

Fig. 2 is a flowchart showing a manufacturing process of the aluminum alloy composite material for brazing.

FIG. 3 is a schematic view showing the structure of an aluminum alloy composite material for brazing according to an example.

Detailed Description

1. Integral formation of brazing aluminum alloy composite material

The aluminum alloy composite material for brazing manufactured by the present invention has a two-layer or three-layer structure in which brazing filler metal is laminated on one surface or both surfaces of a core material. The aluminum alloy composite material for brazing may have a three-layer structure in which a core material, a brazing material, and a sacrificial corrosion-preventing material are laminated to improve corrosion resistance.

The cladding rate of the brazing filler metal is 1-20%, and the cladding rate of the sacrificial corrosion-resistant material is 5-15%. The cladding ratio is a ratio obtained by dividing the thickness of each layer by the final overall thickness. The overall thickness is not particularly limited, but is usually preferably about 0.2 to 2.0mm as a plate material or a pipe material.

2. Chemical composition

2.1. Chemical composition of core material

Si of the core material has an effect of forming a fine intermetallic compound of Al-Mn-Si system and improving strength. The intermetallic compound can control recrystallization behavior during brazing heating, and can improve Erosion resistance (Erosion) of the material. When the content of Si is less than 0.2 mass%, the effect is lowered, and when the content of Si exceeds 0.7 mass%, the melting point of the alloy is lowered, and the melting corrosion of the brazing filler metal in the brazing heating becomes remarkable.

Industrially, fe of the core material is an inevitable element contained in the aluminum alloy. Fe forms coarse intermetallic compounds during casting, and when the number of the intermetallic compounds increases, the number of nuclei for recrystallization during brazing also increases. Further, when the recrystallized nuclei increase at the time of brazing, crystal grains are refined, and erosion along grain boundaries increases, whereby brazeability decreases. Accordingly, the content of Fe is 0.7 mass% or less.

The Cu of the core material improves the strength of the brazing aluminum alloy composite material. When the content of Cu is less than 0.1 mass%, the strength is not sufficiently improved. When the Cu content exceeds 0.8 mass%, the melting point thereof is lowered and melting occurs at the time of brazing.

Mn of the core material increases the strength by dispersion strengthening by generating a fine intermetallic compound in the core material. Further, mn is an element for increasing the size of recrystallized grains during brazing to improve brazeability. When the Mn content of the core material is less than 0.7 mass%, the effect of improving the strength may be insufficient. When the Mn content of the core material exceeds 2 mass%, coarse intermetallic compounds are generated at the time of casting, and the plastic workability is remarkably reduced.

The elements described above are the main elements contained in the core material, but one or two or more of Mg at 0.3 mass% or less, cr at 0.3 mass% or less, zr at 0.3 mass% or less, and Ti at 0.3 mass% or less may be contained in the core material.

Mg in the core material is an element whose strength is greatly improved by adding a small amount. When soldering is performed using Flux (Flux), mg reacts with the Flux during soldering heating, and inhibits the action of the Flux, thereby deteriorating the solderability. Therefore, the upper limit of the Mg content is set to 0.30 mass%. The smaller the content of Mg, the lower the strength-improving effect, but the reaction with the flux is reduced and the brazeability is improved. Therefore, mg is not necessarily contained, and the lower limit of the Mg content is 0 mass%.

Cr and Zr in the core material are contained for the purpose of improving strength and controlling the recrystallization size generated during brazing. The upper limit of the content of Cr and Zr is 0.3% by mass. This is because, when the content of Cr and Zr exceeds 0.3 mass%, coarse intermetallic compounds are generated and the formability is lowered.

Ti of the core material may be contained for the purpose of refining crystal grains or improving corrosion resistance. When the content of Ti exceeds 0.3 mass%, coarse intermetallic compounds are generated, and formability is degraded.

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

2.2. Chemical composition of solder

The Si of the brazing filler metal improves the brazeability. When the Si content of the brazing filler metal is less than 6 mass%, the brazeability becomes insufficient. On the other hand, if the Si content of the brazing filler metal exceeds 13 mass%, cracking is likely to occur during production, and the manufacturability is lowered.

Industrially, fe of the brazing filler metal is inevitably contained in the alloy. Fe in the brazing filler metal is likely to form Al-Fe-based or Al-Fe-Si-based compounds. The formation of Al-Fe-Si compounds reduces the effective Si content, and the formation of Al-Fe or Al-Fe-Si compounds reduces the fluidity of the brazing material during brazing, thereby impairing the brazing properties. When Fe of the brazing filler metal exceeds 0.8 mass%, the brazing property-hindering effect becomes remarkable.

The above is a main element of the brazing filler metal, but the brazing filler metal may contain one or two or more of 1.0 to 3.0 mass% of Mg, 0.05 to 0.2 mass% of Bi, and 0.01 to 0.05 mass% of Sr.

Mg in the brazing filler metal reacts with an oxide film that inhibits brazing in an inert atmosphere or a vacuum atmosphere during brazing heating, and the oxide film is broken. When the Mg content of the brazing filler metal is less than 1.0 mass%, the effect of breaking the oxide film is insufficient. On the other hand, if the Mg content of the brazing filler metal exceeds 3.0 mass%, cracking is likely to occur during production, and the manufacturability is lowered.

Bi in the brazing filler metal has an effect of promoting the destruction of the oxide film by Mg, and the brazeability is improved. When the Bi content of the brazing filler metal is less than 0.05 mass%, the effect of promoting the destruction of the oxide film by Mg becomes insufficient. On the other hand, when the Bi content of the brazing filler metal exceeds 0.2 mass%, bi is excessively oxidized during production and brazing, and the brazeability is lowered.

The Sr of the brazing filler metal suppresses the generation of coarse Si particles, and improves plastic workability and brazeability. When the Sr content of the brazing filler metal is less than 0.01 mass%, the effect of suppressing the generation of coarse Si particles becomes insufficient. On the other hand, when the Sr content of the brazing filler metal is 0.05 mass% or more, an Al — Si — Sr compound is generated, and plastic working may be reduced.

2.3. Chemical composition of sacrificial resist material

Industrially, si and Fe of the sacrificial corrosion-resistant material are inevitable elements contained in the aluminum alloy. The upper limit of the Si content is 0.6 mass%, and the upper limit of the Fe content is 0.7 mass%.

When the contents of Si and Fe of the sacrificial corrosion-resistant material exceed the upper limit, the self-corrosion resistance of the sacrificial corrosion-resistant material may decrease, and the lifetime as a sacrificial layer may be shortened. The lower the contents of Si and Fe, the better the corrosion resistance, so the lower limit of the contents of Si and Fe is 0 mass%. However, since the cost increases when the concentrations of Si and Fe are reduced, about 0.05 mass% is an industrial lower limit.

Zn of the sacrificial corrosion-resistant material lowers the potential of the sacrificial corrosion-resistant material, and imparts a sacrificial corrosion-resistant effect. The sacrificial anticorrosive effect of the sacrificial anticorrosive material can be sufficiently exhibited by setting the Zn content to 0.5 mass% or more. On the other hand, by limiting the Zn content to 5 mass% or less, the following possibility can be reduced: the corrosion rate becomes too high, and therefore, the corrosion resistance of the entire brazing aluminum alloy composite material is lowered.

The above is a main element of the sacrificial anticorrosive material, but the sacrificial anticorrosive material contains at least one of 0.7 to 2 mass% of Mn and 0.5 to 2.5 mass% of Mg.

Mn in the sacrificial corrosion inhibitor generates a fine intermetallic compound in the alloy, and thereby improves the strength of the sacrificial corrosion inhibitor by dispersion strengthening. When the Mn content of the sacrificial anticorrosive material is less than 0.7 mass%, the effect of improving the strength may be insufficient. On the other hand, when the Mn content of the sacrificial corrosion inhibitor exceeds 2 mass%, coarse intermetallic compounds are generated at the time of casting, and the plastic workability is remarkably reduced.

Mg generation of sacrificial corrosion resistant materials ₂ Si、MgZn ₂ The strength is obviously improved. When the Mg content of the sacrificial anticorrosive material is less than 0.5 mass%, the effect of improving the strength may be insufficient. On the other hand, if the Mg content of the sacrificial anticorrosive material exceeds 2.5 mass%, the melting/segregation occurs during brazing due to a decrease in the solidus temperature, and the corrosion resistance is impaired.

3. Method for manufacturing aluminum alloy composite material for brazing

Fig. 2 shows steps of a method for producing an aluminum alloy composite material for brazing according to an embodiment of the present invention. The method comprises the following steps: and a step of laminating an aluminum alloy ingot (first material) having a thickness of several hundred mm with a second material and a third material prepared by hot rolling or the like, and integrating them by hot cladding rolling. The present invention improves the yield of the brazing aluminum alloy composite material produced by these steps. In the following description, the second material and the third material may be referred to as leather materials. In the following description, hot rolling performed when producing the skin material is described as hot rolling only, and hot rolling performed when integrating the first material with the skin material is described separately from clad rolling.

3.1. Method for manufacturing leather material

First, a method for producing the leather 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 composed of a second material as a raw material of a brazing material of an Al — Si alloy and a third material as a raw material of a sacrificial anticorrosive material such as an Al — Zn alloy. The manufacturing method of the second material and the third material is substantially the same, and therefore, the description is common.

First, raw materials of aluminum, an aluminum alloy master alloy, an aluminum alloy material, and the like are mixed and melted to obtain an aluminum alloy melt. Melting and composition adjustment are performed in two furnaces, a melting furnace and a holding furnace. The aluminum alloy melt prepared in the melting furnace is transferred to a holding furnace, and melt processing is performed to finally adjust the composition. In the case of manufacturing the second material, the chemical composition of the brazing material is adjusted, and in the case of manufacturing the third material, the chemical composition of the sacrificial corrosion-preventing material is adjusted.

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

While maintaining the melt at a temperature of about 700 ℃ in a holding furnace, dehydrogenation and removal of the inclusions are performed by using flux or blowing a gas such as Ar gas. The molten metal having completed these treatments is cast, but the dehydrogenation treatment and the molten metal treatment are also performed in the middle of the period from the holding furnace to the casting machine. The dehydrogenation treatment can be performed by blowing Ar gas so as to be dispersed as bubbles. In the melt treatment, inclusions in the melt are removed by passing the melt through a ceramic filter.

If necessary, an Al alloy wire containing Ti and B may be added as a refiner at a constant rate between the holding furnace and the casting machine for refining the ingot structure. The Casting of the skin material was performed by DC Casting (Direct Chill Casting). The casting speed of the skin material is usually 40 to 60 mm/min. The casting temperature of the second material as a raw material of the brazing filler metal is 630 to 700 ℃. The casting temperature of the third material as a raw material of the sacrificial corrosion-resistant material is 680 to 720 ℃.

The width of the skin material mold may be determined depending on the facility, but it is preferable to select the skin material after hot rolling so that the slab width of the skin material becomes approximately the same as the ingot width of the core material. This is because, in the present invention, when the ingot width of the skin material is much smaller than the ingot width of the core material, the condition that the sheet width of the skin material after clad-rolling is only 0 to 50mm smaller than the ingot width of the core material is not satisfied. On the other hand, when the ingot width of the skin material is larger than the ingot width of the core material, the skin material needs to be greatly trimmed (Edge cut) after clad rolling, and the yield is lowered.

In order to remove the entanglement of oxides on the surface of the ingot of the skin material formed by the above casting, the ingot was subjected to surface cutting. The surface cutting amount may be set according to the surface state of the ingot as long as it is 3mm or more. Before the surface cutting, the cast starting part and/or the end part are sometimes cut. This is because the structure formed by casting is not stable at the beginning and/or end. Typically the length of the cut is around 150 mm. Sometimes, the cutting is not performed at the stage of the ingot, and the start portion and/or the end portion are cut in the hot rolling process.

The ingot of the skin material was heated by hot rolling, but the temperature was near 480 ℃. Heating to high temperatures wastes energy and also causes oxide film growth on the ingot surface. The heating time of the ingot is usually 2 hours or more.

The hot rolling of the skin material can be carried out by a conventional method, and the skin material having a predetermined thickness can be obtained by cutting after the rolling. The predetermined thickness is a thickness determined based on the thickness of the ingot of the core material after surface cutting and the cladding ratio of the cladding material (the ratio of the thickness of the cladding material to the entire thickness), and target thicknesses for hot rolling are set for the second material and the third material, respectively. The second material and the third material can be formed as leather materials as described above.

Before the skin materials (second material, third material) and the cast piece (first material) of the core material are laminated, the surface of the skin material may be subjected to a brushing process or a chemical conversion treatment in order to improve the skin-sticking property at the time of lamination. Further, the skin material may be cut in the width direction and the longitudinal direction by a saw before being laminated with the ingot (first material) of the core material.

If necessary, the slab obtained by hot rolling is cut with a saw so as to have a target width and length. In the present invention, the width of the thick plate of the skin material needs to be smaller than the ingot width of the core material by only 0 to 50mm. The specific cutting amount may be set according to the width of the skin material obtained by hot rolling and the width of the ingot of the core material.

3.2. Method for manufacturing core material

Next, a method for producing the first material as a raw material of the core material will be described. The melting and casting method of the first material may be the same as the above-described cladding material, and the casting conditions (temperature, melt processing, addition of a refiner, mold size, casting speed, and the like) may be adjusted to conditions suitable for the production of the first material.

Next, cutting of the cast start and/or end of the ingot of the first material is performed. The cast start and/or end of the ingot of the first material is cut for the same reasons as the skin material. The length of the cast start and/or end of the cut ingot of the first material is typically about 150mm here. Instead of cutting at the stage of the ingot of the first material, a portion corresponding to the cast starting portion and/or end portion may be cut in a clad-rolling, cold-rolling, or Slit (Slit) process. However, when the cutting is performed after the clad-rolling, chips of the sheet material in which the skin material and the core material are integrated are formed, and the recyclability is greatly lowered, so it is preferable to cut the cast starting portion and/or end portion in advance at the stage of the ingot of the first material.

When the ingot of the core material is homogenized, the temperature of the homogenization treatment is set to 550 to 650 ℃. The time for the homogenization treatment is not particularly limited, but is preferably within 12 hours from the viewpoint of economy. Further, the homogenization treatment of the ingot of the core material is not necessarily performed.

Preferably, 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 on the surface-cut surface grows due to the heating in the homogenization treatment. The upper and lower surfaces of the cast block are subjected to surface cutting of at least 3mm or more. The thickness of the ingot of the core material after surface cutting is strictly set for controlling the cladding ratio, and surface cutting is performed so as to be the thickness. As described above, an ingot (first material) of the core material can be formed.

In order to prevent edge cracking after clad rolling, the end surfaces of the core ingot in the width direction may be subjected to surface cutting. In this case, the surface of the end face may be cut so as to have a width of 0 to 50mm larger than the width of the hot-rolled skin material. In addition, in order to improve the pressure-bonding property in the cladding rolling, the ingot of the core material whose surface has been cut may be brushed or subjected to etching treatment with caustic soda or the like.

3.3. Lamination

The overlapped material is produced by overlapping the first material and the leather materials (second material and third material) prepared as described above in the thickness direction. In this case, the first material is sandwiched between the second material and the third material in the thickness direction in an overlapping order. In the subsequent heating process, the first to third materials are generally fixed with Iron bands (Iron bands) in such a manner that the first to third materials do not deviate from each other. Instead of the fixation with the iron band, the overlapping material may be welded, or both the welding and the fixation with the iron band may be used.

In the present invention, the width of the skin material (second material, third material) when laminated needs to be smaller by 0 to 50mm than the width of the ingot (first material) of the core material. When the width of the skin material is larger than the width of the first material, the skin material is exposed from the first material during clad-rolling, and this causes skin overflow, which lowers the yield and productivity. On the other hand, when the width of the skin material is smaller than the width of the first material by 50mm, the skin material does not spread to the end of the core material during the cladding rolling, and the cladding ratio of the end is reduced, so that the required amount of cut edges increases, and the yield is reduced. When the strength of the leather material is equal to or greater than the strength of the first material, the width of the leather material is preferably close to the width of the first material.

The length of the overlapping material may be set based on the specification of the apparatus for manufacturing the overlapping material. For example, from the viewpoint of handling, the length of the overlapping material may be 3m or more. The upper limit of the thickness of the clad material may be set based on the maximum thickness that can be rolled by the hot rolling mill for cladding rolling.

In the case of manufacturing an aluminum alloy composite material for brazing having a two-layer structure of a core material and a brazing material, only the first material and the second material may be stacked in the thickness direction and clad-rolled.

3.4. Cladding rolling

When a rolled sheet is formed in the clad rolling, the clad material is heated to a clad rolling temperature. In the present invention, heating before clad-rolling is performed at 470 to 550 ℃ for 2 hours or more. When the heating temperature before the cladding rolling is less than 470 ℃, the pressure bonding between the skin material and the core material becomes difficult. On the other hand, when the heating temperature before clad-rolling exceeds 550 ℃, the Mn-based intermetallic compound in the core material becomes coarse, and the crystal grains of the core material after brazing become fine.

The heating time before clad-rolling is set to 2 hours or more. After 2 hours, the start of clad-rolling is usually waited for in a heated state according to the operating conditions of the equipment after the next step, and the upper limit of the waiting time is about 18 hours. By limiting the heating time in this manner, variations in characteristics due to variations in heating time can be reduced.

Cladding-rolling the heated overlapped material by using a hot cladding rolling mill. The starting temperature of cladding rolling is set to 420 to 500 ℃ or higher. The starting temperature of the clad-rolling may be measured at the side surface or the upper surface (skin material) or the lower surface (skin material) of the ingot. The rolling pass of the clad-rolling was started within 5 minutes after the measurement of the rolling start temperature.

Clad rolling of overlapping materials typically includes a light reduction rolling pass, referred to as a Bonding pass, followed by a typical rolling pass. The bonding pass is a rolling pass for bonding the skin material and 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 the cladding rolling is not particularly limited, but is usually 200 to 350 ℃.

3.5. Cold rolling/annealing

The sheet thickness of the product (aluminum alloy composite material for brazing) was set by cold rolling the rolled sheet obtained by clad rolling in several passes. The number of cold rolling passes may be determined according to the rolling capacity of the rolling mill. Hardening and tempering are performed by performing heat treatment after the intermediate pass and the final pass of cold rolling. That is, annealing is performed on a coil of a rolled sheet after clad-rolling and before cold-rolling, a coil having a predetermined thickness in the middle of the cold-rolling pass, and a coil having been subjected to cold-rolling. The number of annealing times may be one or more, and may be two or more. Further, the annealing conditions may be selected to be optimum for each of the produced aluminum alloy composite materials for brazing,

3.6. surface treatment

For the sake of solderability and formability, the coil before annealing and the coil after cold rolling may be subjected to surface treatment.

3.7. Slitting process

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

4. Use method of aluminum alloy composite material for brazing

The aluminum alloy composite material for brazing manufactured as described above is used as a refrigerant passage constituting member such as a radiator and a heater core of a heat exchanger for an automobile. The aluminum alloy composite material for brazing is manufactured into the shape of a plate through bending and drawing, is compounded with fin materials and pipes to manufacture the shape of a core of a heat exchanger, and then is integrated through a brazing process. The following method was used for brazing: a so-called CAB (controlled atmosphere brazing) method in which heating is performed in a non-oxidizing atmosphere using a non-corrosive flux; or VB (vacuum brazing) method in which heating is performed in a vacuum atmosphere without using flux.

[ examples ]

Through the steps shown in fig. 2, an aluminum alloy composite material for brazing having a three-layer structure shown in fig. 3 was produced. The following description is made in detail.

1. Production of second Material as raw Material for brazing Material

In order to produce an Al-12 mass% Si alloy ingot, an aluminum alloy melt was obtained by mixing and using a melting furnace. The temperature of the melt is set to 700-850 ℃. The obtained melt was transferred to a holding furnace, and casting was started after dross removal and adjustment of composition and temperature. Between the holding furnace and the casting machine, degassing treatment and removal of the inclusions by a ceramic filter were performed. In addition, sr is added to the present alloy for the purpose of refining the structure.

The casting is performed by vertical semi-continuous casting (so-called DC casting). A mold having a thickness of 500mm and a width of 1290mm was used to obtain an ingot of about 5 tons. The casting temperature is 630 to 670 ℃ and the casting speed is 50 to 60 mm/min. The temperature of the holding furnace is set to 660 to 710 ℃.

The composition of the obtained ingot is shown in table 1.

[ Table 1]

	Si	Fe	Cu	Mn	Zn	The remaining part
							Core material (first material)	0.49	0.18	0.44	1.20	-	Al
Sacrificial anticorrosion material (third material)	0.25	0.26	0.09	1.21	1.44	Al
							Brazing filler metal (second material)	11.97	0.22	-	-	-	Al

The numerical values in table 1 show the contents (% by mass). The content of elements whose numerical values are not described in table 1 is 0.02 mass% or less. The upper and lower surfaces of the ingot were subjected to surface cutting of 10mm or more, and then heated to 480 ℃ to be subjected to hot rolling. The second material is produced by hot rolling to a thickness set for the laminating step and cutting to a predetermined length.

2. Production of a third Material as a raw Material for a sacrificial Corrosion-resistant Material

In order to produce an Al-1.25 mass% Mn-1.5 mass% Zn alloy ingot, an aluminum melt was obtained by mixing and using a melting furnace. The temperature of the melt is set to 700-850 ℃. The obtained melt was transferred to a holding furnace, and casting was started after dross removal and adjustment of composition and temperature.

Between the holding furnace and the casting machine, degassing and a treatment for removing the inclusions by a ceramic filter were performed. Further, an Al-Ti-B alloy is added for the purpose of refining the structure. The casting was carried out by vertical semi-continuous casting (so-called DC casting) using a mold having a thickness of 500mm and a width of 1290mm, giving about 6 tons of ingots. The casting temperature is 680-720 ℃, and the casting speed is 40-50 mm/min. The temperature of the holding furnace is set to 700 to 750 ℃. The composition of the obtained ingot of the third material is shown in table 1. Elements whose numerical values are not described in the table are 0.02 mass% or less.

The ingot was homogenized at 500 ℃ for 8 hours. The homogenized ingots were subjected to surface cutting of 10mm or more on the upper and lower surfaces thereof, and then heated at 480 ℃ for hot rolling. The third material is produced by hot rolling to a thickness set for the cladding process and cutting to a predetermined length.

3. Production of a first Material as a raw Material for a core Material

In order to produce an ingot of the first material, an aluminum melt is obtained by a melting furnace in combination. The temperature of the melt is set to 700-850 ℃. The obtained melt was moved to a holding furnace, and casting was started after dross removal and adjustment of the composition and temperature.

Between the holding furnace and the casting machine, degassing and a treatment for removing the inclusions by a ceramic filter were performed. Further, an Al-Ti-B alloy is added for the purpose of refining the structure. The casting was carried out by vertical semi-continuous casting (so-called DC casting) using a mold having a thickness of 500mm and a width of 1350mm, and about 6 tons of ingots were obtained. The casting temperature is 680-720 ℃, and the casting speed is 40-50 mm/min. The temperature of the holding furnace was 710 to 760 ℃.

The composition of the obtained ingot of the first material is shown in table 1. The content of elements whose numerical values are not described in the table is 0.02 mass% or less. An ingot length of 0.2m was cut and then the ingot was subjected to a homogenization treatment at 500 ℃. The holding time for the homogenization treatment was set to 7 hours. Note that this homogenization treatment may be omitted. By performing the homogenization treatment, even if the heating time before the subsequent clad rolling varies, the characteristics can be stabilized.

The ingot after the homogenization treatment was subjected to surface cutting to thereby obtain a thickness of 480mm. Further, in order to prevent the fracture of the end face, only 5mm surface cutting was performed on the end face.

4. Lamination

A first material having a length of 3.32m and a width of 1.34m and a thickness of 0.48m, a second material having a length of 3.09m and a width of 1.31m and a thickness of 0.07m, and a third material having a length of 3.31m and a width of 1.34m and a thickness of 0.08m were laminated in the thickness direction.

5. Cladding rolling

Next, clad rolling of the clad material is performed to form a rolled sheet. Heating was performed at 470 to 490 ℃ for 8 hours before clad-rolling, and the clad-rolled steel sheet was supplied after the overlapping material was placed on the conveying line of the hot rolling mill and the iron band was removed. The starting temperature of the clad-rolling was set to 450 ℃, and the welding pass under light reduction was performed, and then, the usual clad-rolling pass was performed, to obtain a hot-rolled coil obtained by winding up a plate material having a width of 1195 mm. The coil temperature at the end of the clad-rolling was 305 ℃.

6. Cold rolling/annealing

A coil of a rolled sheet obtained by clad rolling was cold-rolled to obtain a sheet material having a thickness of 1.4mm, and the sheet material was wound to obtain a coil. The coil was held for 3 hours in an inert atmosphere at 360 to 370 ℃ (360 to 380 ℃). The rolled sheet after the intermediate annealing was cold-rolled to a thickness of 0.8mm. The standard deviation of the thickness of the plate at this time was 1.7. Mu.m. Further, the coil of a rolled sheet having a thickness of 0.8mm was subjected to final annealing in an atmosphere of 360 to 380 ℃ (380 ℃ C.) for 3 hours.

7. Slitting process

The coil of the rolled sheet subjected to the final annealing was cut at the beginning and end by slitting. Note that the cladding ratio does not change due to the slitting process.

8. Evaluation results

Samples were taken from the beginning and end of the coil of the aluminum alloy composite material for brazing produced as described above, and the cladding ratios of the brazing filler metal and the sacrificial anticorrosive material were measured.

Table 2 shows the results of the measurement of the cladding ratio.

[ Table 2]

The values in table 2 represent cladding ratio (%). The end 1 is a sample taken from one end portion in the width direction of the brazing aluminum alloy composite material, and the end 2 is a sample taken from an end portion opposite to the end 1. The center is a sample taken from the center in the width direction of the brazing aluminum alloy composite material. T is the sample taken from the beginning of the coil and B is the sample taken from the end of the coil. As shown in table 2, the cladding ratio was within ± 1% from the average value at all positions in the width direction, and the cladding ratio was uniform in the entire region in the width direction.

The aluminum alloy composite material for brazing described above is bent or the like to be processed into a plate shape, and is combined with a fin material, a tube material, or the like to be brazed to form an evaporator. The brazing is performed by heating at a temperature in the range of 590 to 610 ℃ in nitrogen gas using a fluoride-based non-corrosive flux. The brazed core is free from leakage and is durable in strength and corrosion resistance.

Description of the reference numerals

1: a tube; 2: a fin; 3: a header plate; 4: and a resin box.

Claims (4)

1. A method of manufacturing an aluminum alloy composite material for brazing, wherein the aluminum alloy composite material for brazing has:

a core material made of an aluminum alloy containing 0.2 to 0.7 mass% of Si, 0.7 mass% or less of Fe, 0.1 to 0.8 mass% of Cu, and 0.7 to 2.0 mass% of Mn, with the remainder being composed of unavoidable impurities and Al; and

a brazing material comprising an aluminum alloy containing 6 to 13 mass% of Si and 0.8 mass% or less of Fe, the balance being made up of unavoidable impurities and Al,

the brazing filler metal is coated on at least one surface of the core material such that the cladding ratio of the brazing filler metal is 1 to 20%,

the manufacturing method of the aluminum alloy composite material for brazing comprises the following steps:

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

a step of forming a second material as a raw material of the brazing filler metal by performing at least melting, casting, hot rolling, and cutting; and

a step of integrating a superimposed material obtained by superimposing the first material and the second material in the thickness direction by hot cladding rolling,

the width of the second material is only 0 to 50mm smaller than the width of the first material at the start of clad-rolling.

2. The method for manufacturing an aluminum alloy composite material for brazing as recited in claim 1,

the core material further contains one or two or more of Mg of 0.3 mass% or less, cr of 0.3 mass% or less, zr of 0.3 mass% or less, and Ti of 0.3 mass% or less.

3. The manufacturing method of an aluminum alloy composite material for brazing according to any one of claims 1 and 2,

the brazing filler metal further contains one or more of 1.0 to 3.0 mass% of Mg, 0.05 to 0.2 mass% of Bi, and 0.01 to 0.05 mass% of Sr.

4. The method for producing an aluminum alloy composite material for brazing as recited in any one of claims 1 to 3,

the aluminum alloy composite material for brazing is formed by laminating a sacrificial corrosion-resistant skin material, the core material and the brazing filler metal in this order, the sacrificial corrosion-resistant skin material is formed of an aluminum alloy containing 0.6 mass% or less of Si, 0.7 mass% or less of Fe and 0.5 to 5.0 mass% of Zn, the aluminum alloy contains 1.0 to 2.0 mass% of one or two of Mn and 0.5 to 2.5 mass% of Mg,

the cladding rate of the sacrificial corrosion-resistant material is 5-15%,

integrating a third material, which is a raw material of the sacrificial corrosion-preventing material, a superimposed material in which the first material and the second material are superimposed in a thickness direction by clad-rolling,

the width of the third material is only 0-50 mm less than the width of the first material at the start of the clad rolling.

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