Composite aluminum alloy material and preparation method and application thereof

Abstract

The invention discloses a composite aluminum alloy material and a preparation method and application thereof. The composite aluminum alloy material comprises a core layer and solder layers located on the two sides of the core layer. And the solder layer comprises the following components in percentage by weight: 5-15wt% of Si, less than or equal to 0.8 wt% of Fe, less than or equal to 0.3 wt% of Cu, 0.1-0.5 wt% of Mg, 0.02-0.2 wt% of Bi, and the balance of Al and inevitable impurities of which each is less than or equal to 0.05 wt%. The welding flux layer of the composite aluminum alloy material is made of low-magnesium aluminum alloy, the magnesium content is 0.1-0.5 wt%, a small amount of Bi element is added into the alloy of the welding flux layer, the fluidity of the welding flux layer is improved, and the quality of welding feet during welding is guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of aluminum alloy composite materials, and in particular to a composite aluminum alloy material and a preparation method and application thereof. Background Art

[0002] Since 1990, aluminum alloy materials have gradually replaced copper as the main material for heat exchangers due to their low density, high thermal conductivity, good mechanical properties and corrosion resistance. Air separation equipment is a device that uses air as raw material, converts air into liquid through compression cycle deep freezing, and then gradually separates and produces inert gases such as oxygen, nitrogen and argon from liquid air through distillation. Air separation equipment is a large and complex system, mainly composed of the following subsystems: power system, purification system, refrigeration system, heat exchange system, distillation system, product transportation system, liquid storage system and control system. The thermal balance of air separation equipment is achieved through refrigeration system and heat exchange system. With the development of technology, heat exchange systems mainly use aluminum plate-fin heat exchangers.

[0003] At present, the composite baffle material for plate-fin heat exchange of air separation equipment generally uses a three-layer alloy of 4004 / 3003 / 4004. In order to ensure the quality of the weld, the brazing layer generally uses a 4004 alloy with a magnesium content of 1.0wt%-2.0wt%. The alloy has a high magnesium content, which causes waste of resources and high production costs. At the same time, during the brazing process, the magnesium content is high, and magnesium vapor and its oxides are deposited on the wall of the vacuum brazing furnace, which increases the frequency of furnace cleaning and also leads to increased costs. Summary of the invention

[0004] In order to solve the above-mentioned deficiencies in the art, the present application aims to provide a composite aluminum alloy material and a preparation method and application thereof.

[0005] According to one aspect of the present application, there is provided a composite aluminum alloy material, comprising: a core layer and solder layers located on both sides of the core layer;

[0006] The solder layer components and weight percentages are: Si 5-15wt%, Fe≤0.8wt%, Cu≤0.3wt%, Mg0.1-0.5wt%, Bi 0.02-0.2wt%, and the rest are Al and inevitable impurities of a single ≤0.05wt%.

[0007] In some examples, the core layer is 3003 alloy.

[0008] In some examples, the solder layer has a recombination rate of 5-20%.

[0009] In some embodiments, the composite aluminum alloy material has a -5 Pa environment for brazing.

[0010] In another aspect of the present application, a method for preparing the composite aluminum alloy material is also provided, comprising:

[0011] Melting is performed according to the composition and weight percentage of the solder layer to obtain a solder ingot;

[0012] After sawing and milling the solder ingot and the core layer ingot, they are composited in the order of solder layer ingot-core layer ingot-solder layer ingot to obtain a composite ingot;

[0013] The composite ingot is hot-rolled to obtain a hot-rolled strip;

[0014] The hot rolled strip is subjected to pressure processing and annealing treatment to obtain a composite aluminum alloy material.

[0015] In some examples, the hot rolling is to hot roll the solder layer ingot-core layer ingot-solder layer ingot to 5-10 mm.

[0016] In some examples, before the solder ingot is combined with the core layer ingot, the process further includes: homogenizing the core layer ingot, and the homogenizing process is optional.

[0017] In some examples, the hot rolling process includes: heating the composite ingot to 450-550° C., keeping the temperature for 2-10 hours, and then rolling the material in a warm state to a thickness of 5-10 mm to obtain a hot-rolled strip.

[0018] In some examples, the annealing temperature is 250-400°C, and the material is kept at the set temperature for 1-5 hours; it is taken out of the furnace and cooled naturally in the air;

[0019] The application of the composite aluminum alloy material of the present application is used to prepare a plate-fin heat exchanger, including:

[0020] Prepare a partition from a composite aluminum alloy material;

[0021] Clean the partitions, seals and fins as required and then assemble them;

[0022] For the assembled core, the vacuum degree is less than 10 -5 Pa environment for brazing.

[0023] Compared with the prior art, this application has at least the following beneficial effects:

[0024] The present application provides a composite aluminum alloy material, wherein the solder layer is a low-magnesium aluminum alloy with a magnesium content of 0.1-0.5wt%. A small amount of Bi element is added to the solder layer alloy of the present application to increase the fluidity of the solder layer and ensure the quality of the solder foot during welding.

[0025] The composite aluminum alloy material of the present application has a low magnesium content, and magnesium vapor and its oxides are less deposited on the vacuum brazing furnace wall, which reduces the frequency of furnace cleaning and reduces production costs; after brazing, less magnesium and its oxides remain in the core, and can be used to produce gases that are sensitive to magnesium and its oxides and are easily reactive. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the composite aluminum alloy material of the present application.

[0027] Figure 2 This is a schematic diagram of the structure of the plate-fin heat exchanger in the exemplary application example of this application.

[0028] Figure 3 , Figure 4 Brazing diagram of composite aluminum alloy material prepared for an exemplary embodiment of the present application.

[0029] Figure 5 , Figure 6 This is a brazing diagram of a composite aluminum alloy material prepared as an example comparative example of this application. DETAILED DESCRIPTION

[0030] The technical solution of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0031] It is particularly important to point out that similar substitutions and modifications made to the present application are obvious to those skilled in the art, and they are all deemed to be included in the present application. Relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present application to implement and apply the technology of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments.

[0032] If no specific conditions are specified in this application, the preparation shall be carried out under conventional conditions or the conditions recommended by the manufacturer. The raw materials or excipients used, as well as the reagents or instruments used, for which the manufacturers are not specified, are all conventional products that can be obtained commercially.

[0033] The application is described in detail below.

[0034] At present, the composite partition material for plate-fin heat exchange of air separation equipment generally uses a three-layer alloy of 4004 / 3003 / 4004. In order to ensure the quality of the weld, the brazing layer generally uses a 4004 alloy with a magnesium content of 1.0wt%-2.0wt%. In this production plan, the magnesium content is 1.0wt%-2.0wt%. The high magnesium content causes waste of resources and high production costs. During the brazing process, the magnesium content is high, and magnesium vapor and its oxides are deposited on the wall of the vacuum brazing furnace, which increases the frequency of furnace cleaning and increases the cost. After brazing, there is a lot of magnesium and its oxides remaining in the core, and it cannot be used to produce gases that are sensitive to magnesium and its oxides and are easy to react with magnesium and its oxides.

[0035] In the process of vacuum brazing, in order to fully break the surface oxide film, the solder layer must contain a certain amount of volatile element magnesium. When heated to 600℃ during brazing, magnesium forms magnesium vapor and evaporates from the solder layer. The magnesium vapor evaporates and breaks the aluminum oxide film on the surface of the composite partition. Under vacuum conditions, the fresh metal covered by the oxide film and the fins and seals form weld feet.

[0036] However, in an oxygen environment, aluminum alloy is extremely easy to oxidize to form an oxide film that affects the quality of the weld, so the vacuum degree of the brazing furnace is one of the key control points of brazing; the present application found that when the vacuum degree of the vacuum brazing furnace reaches 10 -5 In the case of Pa, 0.1wt% of magnesium in the solder layer can effectively break the surface oxide film and form a good solder foot. At the same time, a small amount of Bi element is added to the solder layer alloy of the present application to increase the fluidity of the solder layer and ensure the quality of the solder foot during welding.

[0037] The technical solution of the present application is further described below in conjunction with specific embodiments.

[0038] Example 1 Preparation of the composite aluminum alloy material of the present application

[0039] The core material is 3003 alloy. The solder layer contains the following components: Si 10wt%, Fe 0.4wt%, Cu0.03wt%, Mg0.15wt%, Bi 0.07wt%, and the rest is Al and inevitable impurities of ≤0.05wt% by mass. The alloy composite rate of the solder layers on both sides is 9%.

[0040] The preparation process includes the following steps:

[0041] Core material / skin material melting and casting: Smelting according to a certain element ratio, through melting, electromagnetic stirring, slag removal, degassing, refining, semi-continuous casting, to obtain a flat ingot of a certain specification.

[0042] Core material homogenization: Heat the ingot to 600℃ in the homogenization furnace and keep the material at temperature for 10 hours;

[0043] Core material / skin material sawing and milling: sawing the ingot according to the specification requirements;

[0044] Compounding and hot rolling: Compound the prepared skin material and core material; preheat the compounded alloy ingot to 500°C, keep the temperature for 5 hours after the material reaches the temperature, and then hot-roll the preheated ingot to a thickness of 5-10mm to obtain a hot-rolled plate and strip;

[0045] Pressure processing and annealing: Through pressure processing and O annealing and tempering treatment; give a certain amount of deformation to the O state annealing material, roll it to a thickness of 2mm, and obtain H14 state products;

[0046] Assembly brazing: Cut into sheets according to the required size and clean them; clean the partitions, seals and fins as required and then assemble them. Figure 3 As shown; for the assembled core, when the vacuum degree is less than 10 -5 Pa environment, brazing is carried out in a vacuum furnace; gas shielded welding is used to weld the head to the core of the plate-fin heat exchange equipment.

[0047] Example 2 Preparation of the composite aluminum alloy material of the present application

[0048] The core material is 3003 alloy, and the solder layer contains the following components: Si 7.5wt%, Fe 0.4wt%, Cu0.03wt%, Mg0.2wt%, Bi 0.1wt%, and the rest is Al and inevitable impurities with a mass of ≤0.05wt% individually. The composite rate of the solder layers on both sides is 12%.

[0049] The preparation process includes the following steps:

[0050] Core material / skin material melting and casting: Smelting according to a certain element ratio, through melting, electromagnetic stirring, slag removal, degassing, refining, semi-continuous casting, to obtain a flat ingot of a certain specification.

[0051] Core material / skin material sawing and milling: sawing the ingot according to the specification requirements;

[0052] Compounding and hot rolling: Compound the prepared skin material and core material; preheat the compounded alloy ingot to 480°C, keep the temperature for 10 hours after the material reaches the temperature, and then hot-roll the preheated ingot to a thickness of 5 to 10 mm to obtain a hot-rolled plate and strip;

[0053] Pressure processing and annealing: Through pressure processing and quenching and tempering treatment at 280℃ for 2h, H24 state products are obtained;

[0054] Assembly brazing: Cut into sheets according to the required size and clean them; clean the partitions, seals and fins as required and then assemble them. Figure 3 As shown; for the assembled core, when the vacuum degree is less than 10 -5Pa environment, brazing is carried out in a vacuum furnace; gas shielded welding is used to weld the head to the core of the plate-fin heat exchange equipment.

[0055] Comparative Example 1: The brazing layer does not add Bi. The core material is 3003 alloy. The solder layer contains the following components: Si7.5wt%, Fe0.4wt%, Cu0.03wt%, Mg0.2wt%, and the rest are Al and inevitable impurities with a single mass of ≤0.05wt%; the composite rate of the solder layers on both sides is 12%.

[0056] The preparation process includes the following steps:

[0057] Core material / skin material melting and casting: Smelting according to a certain element ratio, through melting, electromagnetic stirring, slag removal, degassing, refining, semi-continuous casting, to obtain a flat ingot of a certain specification.

[0058] Core material / skin material sawing and milling: sawing the ingot according to the specification requirements;

[0059] Compounding and hot rolling: Compound the prepared skin material and core material; preheat the compounded alloy ingot to 480°C, keep the temperature for 10 hours after the material reaches the temperature, and then hot-roll the preheated ingot to a thickness of 5 to 10 mm to obtain a hot-rolled plate and strip;

[0060] Pressure processing and annealing: Through pressure processing and quenching and tempering treatment at 280℃ for 2h, H24 state products are obtained;

[0061] Assembly brazing: Cut into sheets according to the required size and clean them; clean the partitions, seals and fins as required and then assemble them. Figure 3 As shown; the assembled core is brazed in a vacuum furnace under a vacuum degree lower than 10-5Pa; the head is welded to the core of the plate-fin heat exchange equipment using gas shielded welding.

[0062] Application Examples

[0063] At vacuum degree ≤10 -5 Under the condition of Pa, the composite aluminum alloy material of the embodiment is assembled and brazed.

[0064] according to Figure 3 and Figure 4 It can be seen that the composite aluminum alloy material prepared in this application, such as Example 1 ( Figure 3 ) and Example 2 ( Figure 4 ) as shown, the weld foot is full.

[0065] Comparative application example 1

[0066] At vacuum degree ≤10 -5 Under the condition of Pa, the composite aluminum alloy material of the comparative example was assembled and brazed.

[0067] like Figure 5 As shown, the weld foot of this comparative example is not full.

[0068] Comparative Application Example 2

[0069] At vacuum degree 10 -3 Under the condition of Pa, the composite aluminum alloy material of Example 1 was assembled and brazed.

[0070] like Figure 6 As shown, the weld foot is not full and has a small amount of pores.

[0071] The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. It should be noted that, for ordinary technicians in this technical field, several improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A composite aluminum alloy material, characterized in that: include: A core layer and solder layers located on both sides of the core layer; The solder layer comprises components and weight percentages of Si 5-15wt%, Fe≤0.8wt%, Cu≤0.3wt%, Mg0.1-0.5wt%, Bi 0.02-0.2wt%, and the rest are Al and inevitable impurities of a single ≤0.05wt%.

2. The composite aluminum alloy material according to claim 1, characterized in that: The core layer is 3003 alloy.

3. The composite aluminum alloy material according to claim 1, characterized in that: The composite rate of the solder layer is 5-20%.

4. The composite aluminum alloy material according to claim 1, characterized in that: The composite aluminum alloy material is less than 10 -5 Pa environment for brazing.

5. A method for preparing the composite aluminum alloy material according to any one of claims 1 to 4, characterized in that: include: Melting the solder layer according to its components and weight percentage to obtain a solder ingot; After sawing and milling the solder ingot and the core layer ingot, they are composited in the order of solder layer ingot-core layer ingot-solder layer ingot to obtain a composite ingot; hot-rolling the composite ingot to obtain a hot-rolled strip; The hot-rolled strip is subjected to pressure processing and annealing treatment to obtain the composite aluminum alloy material.

6. The preparation method according to claim 5, characterized in that: The hot rolling treatment is to hot roll the solder layer ingot-core layer ingot-solder layer ingot to 5-10 mm.

7. The preparation method according to claim 5, characterized in that: Before the solder ingot is combined with the core layer ingot, the method further includes: subjecting the core layer ingot to a homogenization treatment.

8. The preparation method according to claim 5, characterized in that: The temperature of the hot rolling treatment is 450-550° C., and the holding time of the hot rolling treatment is 2-10 hours.

9. The preparation method according to any one of claims 5 to 8, characterized in that: The annealing temperature is 250-400° C., and the annealing holding time is 1-5 hours.

10. An application of the composite aluminum alloy material according to any one of claims 1 to 4, characterized in that: For preparing plate-fin heat exchangers, including: Prepare a separator from the composite aluminum alloy material; The partitions, seals and fins are cleaned and assembled as required; For the assembled core, the vacuum degree is less than 10 -5 Pa environment for brazing.

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