Aluminum alloy core material for heat exchangers, and heat exchange tubes and heat exchangers using the same

Abstract

The present invention provides an aluminum alloy core material for heat exchangers, which contains an aluminum alloy material, and a heat exchange tube and a heat exchanger using the same. [Solution] The aluminum alloy material contains Mn: 0.20-1.20%, Fe: 0.08%-0.25%, Ti: 0.08%-0.25%, Si: 0.03%-0.12%, Cu: 0-0.35%, Zn: 0-3.0%, Zr: 0-0.4%, V: 0-0.4%, Cr: 0-0.5%, RE: 0-0.5%, and the remainder is aluminum and unavoidable impurities, where RE is a rare earth element.

Description

Cross-reference to related applications

[0001] This application is based on and claims priority to a Chinese patent application bearing application number 202210444325.3 and filing date April 25, 2022, the entire contents of which are hereby incorporated by reference into this application. [Technical field]

[0002] The present disclosure relates to the field of heat exchange technology, and more particularly to an aluminum alloy core material for heat exchangers, and a heat exchange tube and a heat exchanger using the same. [Background technology]

[0003] In applications where a heat exchanger exchanges heat with air, the corrosion resistance of a heat exchange tube in air not only affects the heat exchange performance of the heat exchanger, but also relates to the service life of the heat exchanger and is an important indicator of the reliability of the heat exchange tube. In the related art, during the use of a heat exchanger, the outer surface of an aluminum alloy heat exchange tube is exposed to a corrosive environment, which will cause local corrosion of the heat exchange tube, leading to refrigerant leakage from the heat exchanger and affecting the service life of the heat exchanger. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, one aspect of the present disclosure proposes an aluminum alloy core material for heat exchangers and a heat exchange tube using the aluminum alloy core material, which contributes to improving the corrosion resistance of the heat exchange tube, and applying the heat exchange tube to a heat exchanger contributes to improving the service life of the heat exchanger. [Means for solving the problem]

[0005] Another aspect of the present disclosure further proposes a heat exchanger. In an embodiment according to one aspect of the present disclosure, an aluminum alloy core material for a heat exchanger is proposed, which includes an aluminum alloy material containing, by mass percentage, 0.20-1.20% Mn, 0.08%-0.25% Fe, 0.08%-0.25% Ti, 0.03%-0.12% Si, 0-0.35% Cu, 0-3.0% Zn, 0-0.4% Zr, 0-0.4% V, 0-0.5% Cr, and 0-0.5% RE, with the remainder being aluminum and unavoidable impurities, where RE is a rare earth element. The aluminum alloy core material comprises a plurality of first unit bodies, a plurality of second unit bodies and a plurality of third unit bodies, the first unit bodies, the second unit bodies and the third unit bodies having the same volume, the average Ti content of the first unit bodies is four times or more the nominal Ti content of the aluminum alloy core material, the average Ti content of the second unit bodies is less than 0.02%, and the average Ti content of the third unit bodies is greater than the average Ti content of the second unit bodies and less than the average Ti content of the first unit bodies.

[0006] In the embodiment of the present disclosure, the aluminum alloy core material includes a plurality of high Ti-content aluminum-based solid solutions and a plurality of low Ti-content aluminum-based solid solutions, where the high Ti-content aluminum-based solid solutions may be understood to refer to one or more consecutive first unit bodies, and the low Ti-content aluminum-based solid solutions may be understood to refer to one or more consecutive second unit bodies.

[0007] The aluminum alloy core material for heat exchangers of the embodiment of the present disclosure has the following beneficial effects: The aluminum alloy core material for heat exchangers of the embodiment of the present disclosure includes an aluminum-based solid solution with a high Ti content and an aluminum-based solid solution with a low Ti content, the average value of the Ti content of the aluminum-based solid solution with a high Ti content is more than four times the nominal value of the Ti content of the aluminum alloy core material, and the average value of the Ti content of the aluminum-based solid solution with a low Ti content is less than 0.02%, and due to the difference in micro-components, a sufficiently large difference in micro-corrosion potential is formed, and such a difference is particularly retained in the hot processing process such as hot extrusion tube making and heat exchanger brazing, and finally distributed in alternating bands in the thickness direction of the heat exchange tube, and the corrosion form is band-like, which enables the corrosion in the thickness direction of the heat exchange tube to be suppressed, thereby effectively improving the pitting corrosion resistance of the heat exchange tube.

[0008] In some embodiments, the first unit body and at least one second unit body at least partially overlap when projected onto a first plane or a second plane, the first plane being a plane parallel to a horizontal plane, and the second plane being a plane that forms an angle α with the first plane, where α is 0°<α≦90°.

[0009] In some embodiments, the aluminum alloy material has a Ti content, in mass percentage, of 0.10 to 0.20%, and more preferably 0.14 to 0.18%.

[0010] In some embodiments, the aluminum alloy material contains 0% Cu by mass. <Cu≦0.35%である。

[0011] In some embodiments, the aluminum alloy material has a Zn content, by mass percentage, of 0%. <Zn≦3.0%である。

[0012] In some embodiments, the aluminum alloy material has a Zr content, by mass percentage, of 0%. <Zr≦0.4%である。

[0013] In some embodiments, the aluminum alloy material has a V content of 0% by mass. <V≦0.4%である。

[0014] In some embodiments, the aluminum alloy material has a Cr content, by mass percentage, of 0%. <Cr≦0.5%である。

[0015] In some embodiments, the content of RE in the aluminum alloy material is 0% by mass. <RE≦0.5%である。

[0016] In some embodiments, in the aluminum alloy material, the single content of the unavoidable impurity elements is ≦0.05% by mass, and the total content is ≦0.15% by mass.

[0017] In some embodiments, in the grain structure of the aluminum alloy core material, when calculated by the number of grains, the proportion of equiaxed grains is 90% or more, and the maximum size of at least 40% of the equiaxed grains exceeds 100 μm. Since the grain size of the aluminum alloy core material affects the pitting corrosion resistance of the later-processed pipe material, the aluminum alloy core material in the embodiments of the present disclosure is mainly equiaxed, with grain sizes concentrated on the order of hundreds of μm, and when calculated by the number of grains, the proportion of grains with a size exceeding 100 μm exceeds 40%.

[0018] In some embodiments, the aluminum alloy core material is mixed with diffusely distributed second phase particles, and the maximum size of at least 90% of the second phase particles is less than 15 μm when calculated by the number of second phase particles. Mn, Fe, Si, Ti and impurity elements in the aluminum alloy material form second phase particles in the aluminum alloy core material, and the dispersed second phase particles can effectively improve the strength of the aluminum alloy core material, but the second phase particles with too large size will reduce the extrusion processing performance of the aluminum alloy core material. Considering all of this, the maximum size of at least 90% of the second phase particles (calculated by the number of second phase particles) in the aluminum alloy core material of the embodiments of the present disclosure is less than 15 μm.

[0019] Another aspect of the embodiment of the present disclosure provides a method for manufacturing the aluminum alloy core material for heat exchangers, comprising the steps of: weighing and mixing the aluminum alloy material according to its components and weight percentages, and then performing semi-continuous ingot casting and homogenization to manufacture the aluminum alloy core material. The homogenization temperature is 550°C to 630°C, and the homogenization time is 1h to 8h. Preferably, the homogenization temperature is 580°C to 620°C, and the homogenization time is 4h to 6h.

[0020] The manufacturing method of the aluminum alloy core material for heat exchangers in the embodiment of the present disclosure has the following beneficial effects: By controlling the composition and mass percentage of the alloying elements, as well as the temperature and time of the homogenization treatment, the manufactured aluminum alloy core material contains an aluminum-based solid solution with a high Ti content and an aluminum-based solid solution with a low Ti content, the average value of the Ti content of the aluminum-based solid solution with a high Ti content is more than four times the nominal value of the Ti content of the aluminum alloy core material, and the average value of the Ti content of the aluminum-based solid solution with a low Ti content is less than 0.02%, and the large difference distribution of the Ti content is the basis of the pitting corrosion resistance effect of the hot extrusion pipe material in the present disclosure.

[0021] In some embodiments, the manufacturing method of the aluminum alloy core material for heat exchanger includes the following steps: aluminum alloy material is weighed and mixed according to its components and weight percentages, put into a melting furnace and melted at 750°C-780°C, then refined in a holding furnace at 740°C-750°C, degassed with high purity Ar, and the hydrogen content of the aluminum alloy liquid after degassing is controlled to 0.13ml / 100g or less (preferably 0.10ml / 100g or less), then add 0.01%-0.03% by mass of Al-5 Ti-1 B grain refiner to the aluminum alloy liquid, perform two-stage filtration, cast after filtration, cast temperature is 705°C-715°C, and homogenization treatment is performed after casting, homogenization temperature is 550°C-630°C, and homogenization time is 1h-8h.

[0022] One aspect of the present disclosure further provides a heat exchange tube comprising a tube wall and at least one heat exchange passage, the heat exchange passage extending in a longitudinal direction of the heat exchange tube, the heat exchange passage being surrounded by a tube wall, and a core material of the tube wall comprising the above-mentioned aluminum alloy core material.

[0023] In the embodiment of the present disclosure, the aluminum alloy core material is processed to produce a heat exchange tube, and the high Ti content aluminum-based solid solution and the low Ti content aluminum-based solid solution are alternately distributed in the thickness direction of the tube wall after being processed into a heat exchange tube.

[0024] The heat exchange tube of the embodiment of the present disclosure has the following beneficial effects: the aluminum-based solid solution with high Ti content and the aluminum-based solid solution with low Ti content alternately distributed in the original aluminum alloy core material after hot extrusion are formed into bands parallel to the tube wall direction, which forms a potential gradient that is alternately distributed microscopically on the tube wall, and such an alternately distributed potential gradient can confine corrosion within the low potential band, and only after the low potential band is consumed can corrosion break through the high potential band and spread to the inside of the tube, which can effectively improve the pitting corrosion resistance of the heat exchange tube.

[0025] In some embodiments, the heat exchange tube is manufactured by a method including an extrusion process using the aluminum alloy core material, and the extrusion ratio of the extrusion process is greater than or equal to 50. When the heat exchange tube is a micro-passage flat tube, the extrusion ratio is greater than or equal to 150. In order to better crush and disperse the second phase particles and to make the microstructure of the tube material dense, the extrusion ratio in the extrusion process needs to be greater than or equal to 50, and the extrusion ratio when extruding the micro-passage flat tube is preferably greater than or equal to 150.

[0026] In some embodiments, the heat exchange tube includes a solder layer, the solder layer being an Al-Si based alloy, the solder layer forms a diffusion layer by silicon diffusion during the brazing process, and the thickness of the diffusion layer is less than 20% of the thickness of the tube wall.

[0027] In the brazing process of heat exchanger products with a welded structure, the Si element in the solder layer diffuses into the heat exchange tube, and with the local dissolution of the heat exchange tube base material, the diffusion of Si is faster and deeper, especially at the grain boundary positions of the heat exchange tube, than at non-grain boundary positions. The diffusion of Si into the tube material changes the components of the tube material, especially the components at the grain boundary positions of the tube material where diffusion is more, which has a negative effect on the corrosion resistance of the tube material. To reduce this negative effect, it is necessary to effectively control the diffusion depth of Si in the solder layer into the tube material, which is preferably not more than 20% of the tube wall thickness of the heat exchange tube. Effect of the Invention

[0028] Another aspect of an embodiment of the present disclosure further provides a heat exchanger including the heat exchange tube described above. The heat exchanger of the embodiment of the present disclosure has the following beneficial effects: Since the above heat exchange tube is adopted, the service life of the heat exchanger is greatly improved.

[0029] In some embodiments, the heat exchanger includes a first tube, a second tube, and a heat exchange tube. A plurality of said heat exchange tubes are spaced apart along a length of a first tube, the heat exchange tube including a heat exchange passage extending along its length, the plurality of heat exchange passages being spaced apart across the width of the heat exchange tube, the heat exchange tube being connected directly or indirectly to the first tube, and the heat exchange tube being connected directly or indirectly to the second tube.

[0030] In some embodiments, the heat exchanger further comprises fins. The fins are connected to the heat exchange tubes, and some of the fins are located between two adjacent heat exchange tubes in the longitudinal direction of the first tube, and the fins are multiple; The material of the fins is an aluminum alloy, and the corrosion potential of the fins is equal to or lower than the corrosion potential of the heat exchange tubes.

[0031] In some embodiments, the surface of the heat exchange tube is precoated with arc zinc spraying or zinc-containing flux. Zn element is added to aluminum alloy to reduce the corrosion potential of the aluminum alloy. Since Zn has a large solid solubility in aluminum alloy, Zn, except for reacting with other alloying elements to form a second phase, usually exists in the form of solid solution in aluminum alloy. When the solid-solubilized Zn shows a distribution from high concentration to low concentration from the surface layer to the inner layer of the heat exchange tube, the corrosion potential of the heat exchange tube shows a distribution from low corrosion potential to high corrosion potential from the surface layer to the inner layer of the heat exchange tube, and such a distribution can effectively improve the pitting corrosion resistance performance of the aluminum alloy heat exchange tube. The zinc pre-arranged on the surface of the heat exchange tube during welding heating diffuses from the surface to the inside to form a concentration gradient, effectively extending the corrosion resistance life of the heat exchange tube.

[0032] The aluminum alloy core material for heat exchangers in the embodiments of the present disclosure comprises an aluminum-based solid solution with a high Ti content and an aluminum-based solid solution with a low Ti content, and due to the difference in micro-components, a sufficiently large difference in micro-corrosion potential is formed, and such difference is particularly maintained during hot processing processes such as hot extrusion tube making and heat exchanger brazing, and is finally distributed in alternating bands in the thickness direction of the heat exchange tube, and the corrosion form is band-like, which enables the corrosion in the thickness direction of the heat exchange tube to be inhibited, thereby effectively improving the pitting corrosion resistance of the tube material.

[0033] The heat exchange tube for a heat exchanger according to the embodiment of the present disclosure employs an aluminum alloy core material having excellent extrusion performance and corrosion resistance, and the manufactured heat exchange tube has high corrosion resistance. Even if a zinc spray coating layer is not added, the heat exchange tube still has high corrosion resistance and relatively high strength.

[0034] The heat exchanger according to the embodiment of the present disclosure employs the heat exchange tube according to the embodiment of the present disclosure, which greatly improves the service life of the heat exchanger. [Brief description of the drawings]

[0035] [Figure 1a] FIG. 2 is an SEM image of a crystal grain at the center of the ingot after homogenization in Example 1. [Figure 1b] FIG. 2 is an SEM image of a crystal grain at a radial 1 / 4 position of the ingot after homogenization in Example 1. [Figure 1c] FIG. 2 is an SEM image of a second phase particle at the center position of the ingot after homogenization in Example 1. [Figure 1d] FIG. 2 is an SEM image of a second phase particle at a radial 1 / 4 position of the ingot after homogenization in Example 1. [Figure 1e] FIG. 2 is an EDS diagram of the Ti element content at the center position of the ingot after homogenization in Example 1. [Figure 1f] FIG. 2 is an EDS diagram of the Ti element content at a radial 1 / 4 position of the ingot after homogenization in Example 1. [Figure 2a] FIG. 2 is an SEM image of crystal grains in the extruded tube of Example 1. [Figure 2b] FIG. 2 is an SEM image of second phase particles in the extruded tube of Example 1. [Figure 3a] FIG. 1 is a typical corrosion morphology diagram of the simulated post-braze zinc sprayed tube manufactured in Example 1 after 4000 h SWAAT. [Figure 3b] FIG. 2 shows typical corrosion morphology of the zinc sprayed tube produced in Example 1 after 3000 h of SWAAT. [Figure 3c] FIG. 1 is a typical corrosion morphology diagram of the zinc-free pipe produced in Example 1 after 4000 h of SWAAT. [Figure 4a] FIG. 1 is an SEM image of a crystal grain at the center of the ingot after homogenization in Example 2. [Figure 4b] FIG. 1 is an SEM image of crystal grains at a radial 1 / 4 position of the ingot after homogenization in Example 2. [Figure 4c] FIG. 1 is an SEM image of a second phase particle at the center of the ingot after homogenization in Example 2. [Figure 4d] FIG. 2 is an SEM image of a second phase particle at a radial 1 / 4 position of the ingot after homogenization in Example 2. [Figure 4e] FIG. 1 is an EDS diagram of the Ti element content at the center position of the ingot after homogenization in Example 2. [Figure 4f] FIG. 1 is an EDS diagram of the Ti element content at a radial 1 / 4 position of the ingot after homogenization in Example 2. [Figure 5a]FIG. 1 is an SEM image of crystal grains in the extruded tube of Example 2. [Figure 5b] FIG. 1 is an SEM image of second phase particles in the extruded tube of Example 2. [Figure 6a] 1 shows typical corrosion morphology of the simulated post-braze zinc sprayed tube produced in Example 2 after 4000h SWAAT. [Figure 6b] 1 shows a typical corrosion morphology of the extruded pipe (zinc-free pipe) produced in Example 2 after 2000 hours of SWAAT. [Figure 7a] FIG. 1 is an SEM image of a crystal grain at the center of the ingot after homogenization in Example 4. [Figure 7b] FIG. 1 is an SEM image of crystal grains at a radial 1 / 4 position of the ingot after homogenization in Example 4. [Figure 7c] FIG. 1 is an SEM image of a second phase particle at the center of the ingot after homogenization in Example 4. [Figure 7d] FIG. 1 is an SEM image of a second phase particle at a radial 1 / 4 position of the ingot after homogenization in Example 4. [Figure 7e] FIG. 13 is an EDS diagram of the Ti element content at the center position of the ingot after homogenization in Example 4. [Figure 7f] FIG. 13 is an EDS diagram of the Ti element content at a radial 1 / 4 position of the ingot after homogenization in Example 4. [Figure 8a] FIG. 1 is an SEM image of crystal grains in the extruded tube of Example 4. [Figure 8b] FIG. 1 is an SEM image of second phase particles in the extruded tube of Example 4. [Figure 9a] 1 shows a typical corrosion morphology of the zinc-sprayed tube produced in Example 4 after 4000 hours of SWAAT. [Figure 9b] 1 shows a typical corrosion morphology of the zinc-sprayed tube produced in Example 4 after 6000 hours of SWAAT. [Figure 10] FIG. 2 is a structural schematic diagram of a heat exchanger according to an embodiment of the present disclosure. [Figure 11] The diffusion of silicon elements in a typical flat tube near the header position in the finless region between the header and fins in the heat exchanger H and H core detected by SEM & EDS. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Examples of the present disclosure will be described in detail below, but the examples described below are illustrative and are intended to explain the present disclosure, and are not intended to limit the present disclosure.

[0037] In the present disclosure, the corrosion resistance performance refers to the general corrosion resistance and pitting corrosion resistance of an aluminum alloy in a corrosive environment, the general corrosion resistance refers to the durability of an aluminum alloy against general corrosion, and the pitting corrosion resistance refers to the durability of an aluminum alloy against pitting corrosion. The corrosive environment includes an air environment and / or a water environment, and may be, for example, an acidic environment, an alkaline environment, a chloride environment, or a combination thereof.

[0038] The aluminum alloy core material in the examples of the present disclosure must be designed in terms of its elemental composition and content in order to satisfy, in addition to corrosion resistance, the strength and processing and manufacturing performance required for components such as heat exchanger tubes. Below, the elemental composition and added amount of the aluminum alloy material contained in the aluminum alloy core material in the examples of the present disclosure will be explained, and in the examples of the present disclosure, unless otherwise explained, the contents of the alloy elements in the aluminum alloy material in the examples of the present disclosure all refer to the mass content.

[0039] The aluminum alloy core material of the present disclosure includes an aluminum alloy material containing an Mn element, and the solid solubility of the Mn element in the aluminum alloy core material at room temperature is relatively low. 6 Mn exists in the form of a second phase and is diffusely distributed in Al. 6 Mn particles can effectively improve the strength of the aluminum alloy core material. 6Since the corrosion potential of Mn is close to that of pure Al, the added Mn element can improve the strength without affecting the corrosion resistance. However, an increase in the Mn content reduces the extrusion processability of the aluminum alloy core material, so the upper limit of the Mn content in the aluminum alloy material of the embodiment of the present disclosure is 1.2%. A certain amount of Mn element can form an Al-Mn-Fe-Si phase with elements such as Fe and Si, and can also reduce the adverse effect of excess Fe and Si on the corrosion resistance of the aluminum alloy core material. In order to effectively reduce the effect of Fe and Si, the lower limit of the Mn content in the aluminum alloy material of the embodiment of the present disclosure is 0.2%.

[0040] Aluminum alloy materials contain Fe and Si elements. Fe and Si are the main impurity elements in electrolytic aluminum raw materials (the upper limit of Fe and Si content in aluminum ingot Al99.70 is 0.10% and 0.20%, respectively), and are also the main alloying and strengthening elements in type 1 aluminum alloys. When Fe exists alone in an Al matrix because the solid solubility of Fe in the Al matrix is ​​low, it is usually 3 It exists in the form of intermetallic compounds such as Fe, and has a high strengthening effect on aluminum alloy core materials. 3 The difference in corrosion potential between Fe and the Al matrix is ​​relatively large, so it is easy to induce pitting corrosion. A small amount of Si exists in the form of solid solution in the Al matrix and has a certain solid solution strengthening effect on the Al matrix, but Si is an element that increases the potential of the aluminum alloy core material, and excessive Si reduces the corrosion resistance performance of the aluminum alloy core material. A certain amount of Mn can reduce the adverse effects of Fe and Si on the corrosion of the aluminum alloy core material to a certain extent, but the contents of Fe and Si still need to be controlled. Usually, the higher the strength of the aluminum alloy core material, the greater the pressure required for extrusion processing, and from the perspective of extrusion performance, the contents of strengthening elements such as Fe and Si also need to be controlled. Considering the purity level of the electrolytic aluminum raw material and the effects of Fe and Si on the corrosion resistance and extrusion performance of the aluminum alloy core material comprehensively, the content of Fe in the aluminum alloy material of the embodiment of the present disclosure is 0.08% to 0.25%, and the content of Si is 0.03% to 0.12%.

[0041] Aluminum alloy materials contain Ti element, and from the viewpoint of the binary phase diagram of Al~Ti, the Al phase diagram is a peritectic reaction. The solid solubility of Ti in Al at the peritectic temperature of 665℃ is 0.15%, and Ti exceeding 0.15% is dissolved in Al and TiAl 3 Although it forms intermetallic compounds, the maximum equilibrium solubility of Ti in aluminum-based solid solutions at high temperatures after the peritectic reaction is about 1.3%. This peritectic reaction is called TiAl 3 This is the process in which the solid phase and the Al liquid phase form a new aluminum-based solid solution solid phase. In the actual casting process, due to insufficient element diffusion, the peritectic reaction usually has difficulty in reaching a complete equilibrium state. Thus, the aluminum-based solid solution formed after the reaction contains residual TiAl 3 Particles are present. Hard TiAl 3 In order to prevent residual particles from affecting the extrusion processability of the aluminum alloy core material, the upper limit of the Ti content in the aluminum alloy material of the embodiment of the present disclosure is 0.25%. However, in the actual casting process, for example, when grain refiners such as Al-Ti-B are added, there are heterogeneous nucleation mass points (for example, TiB 2 The solidification of the alloy deviates from the equilibrium composition because of the interaction between different alloying elements (e.g., Ti-rich regions are formed near the nucleation mass points) and the metallurgical reaction of Ti in Al is affected (e.g., B can reduce the critical content of the peritectic reaction of Ti in Al from 0.15% to about 0.01%). The lower limit of the Ti content in the aluminum alloy material of the embodiment of the present disclosure is 0.08%.

[0042] TiAl 3The nominal Ti content in is 37%, and the Ti content of the aluminum-based solid solution formed by the peritectic reaction at high temperature is about 1.3% at most, so that an aluminum-based solid solution with a high Ti content is formed in the aluminum alloy core material, and in addition to this aluminum-based solid solution with a high Ti content, an aluminum-based solid solution with a low Ti content also exists in the aluminum alloy core material. Due to the difference in micro-components, there is a difference in corrosion potential, and such a difference is particularly retained in the hot processing processes such as homogenization of the ingot after casting, hot extrusion pipe making, and heat exchanger brazing, and is distributed in alternating bands in the thickness direction of the hot extrusion pipe material, and the corrosion form is band-like, which enables the corrosion in the thickness direction of the hot extrusion pipe material to be inhibited, thereby effectively improving the pitting corrosion resistance of the pipe material. In order to have a sufficiently large micro-corrosion potential difference in the manufactured pipe material and improve the pitting corrosion resistance performance, the Ti content of the aluminum-based solid solution with a high Ti content in the aluminum alloy core material should be four or more times the nominal Ti content of the aluminum alloy core material, and the Ti content of the aluminum-based solid solution with a low Ti content should be less than 0.02%.

[0043] In some embodiments, the aluminum alloy material contains Cu element, and the Cu element added should be added in an appropriate amount to avoid the Cu element reacting with Al and the other alloy elements added to form a coarse second phase, which affects the corrosion resistance of the alloy. From the Al-Cu binary phase diagram, the maximum solid solubility of Cu in Al at a high temperature of 548°C is 5.65%, and the equilibrium solid solubility decreases with decreasing temperature, being about 0.45% at 300°C and about 0.1% at room temperature. During the solidification and subsequent processing and welding process of the alloy, due to the influence of the high temperature residence time limit and solidification rate, etc., Cu usually cannot reach a complete equilibrium state in Al, and even if it is slightly supersaturated, it is difficult to form a second phase precipitation, so the amount of Cu element added in the aluminum alloy material of the embodiment of the present disclosure is 0.35% or less.

[0044] In some embodiments, the aluminum alloy material contains Zn element, and the added Zn element needs to be added in an appropriate amount to avoid the added Zn element reacting with Al and the added alloying element to form a coarse second phase and affecting the corrosion resistance performance of the alloy. The maximum solid solubility of Zn in aluminum-based solid solution can reach 83.1% at 381°C, and the solid solubility continues to decrease with decreasing temperature, about 32% at 277°C, and about 5.6% at 125°C. Considering that Zn has a certain solid solution strengthening effect on Al, a relatively high Zn content will reduce the extrusion processing performance of the aluminum alloy core material, and when the Zn content is about 3.00% or less, the effect of reducing the corrosion potential of Al by Zn is relatively large, the added amount of Zn element in the aluminum alloy material is not more than 3.00%.

[0045] Therefore, one aspect of the embodiment of the present disclosure proposes an aluminum alloy core material for a heat exchanger, which includes an aluminum alloy material containing, by mass percentage, 0.20-1.20% Mn, 0.08%-0.25% Fe, 0.08%-0.25% Ti, 0.03%-0.12% Si, 0-0.35% Cu, 0-3.0% Zn, 0-0.4% Zr, 0-0.4% V, 0-0.5% Cr, and 0-0.5% RE, with the remainder being aluminum and unavoidable impurities, where RE is a rare earth element. the aluminum alloy core material comprises a plurality of first unit bodies, a plurality of second unit bodies and a plurality of third unit bodies, the first unit bodies, the second unit bodies and the third unit bodies having the same volume, the average Ti content of the first unit bodies is four times or more the nominal Ti content of the aluminum alloy core material, the average Ti content of the second unit bodies is less than 0.02%, and the average Ti content of the third unit bodies is greater than the average Ti content of the second unit bodies and less than the average Ti content of the first unit bodies.

[0046] The volumes of the first unit body, the second unit body, and the third unit body are not limited to a specific range, and as long as there is a volume region that satisfies the above conditions, any of these may be understood as a selectable volume range for the first unit body, the second unit body, and the third unit body. In addition, the volume may be sufficiently small, for example, a volume of 1 μm 3 ~1000μm 3 (For example, 1 μm 3 , 5 μm 3 , 10μm 3 , 20μm 3 , 50μm 3 , 100μm 3 , 1000μm 3 etc.).

[0047] In the embodiment of the present disclosure, the aluminum alloy core material includes a plurality of high Ti-content aluminum-based solid solutions and a plurality of low Ti-content aluminum-based solid solutions, where the high Ti-content aluminum-based solid solutions may be understood to refer to one or more consecutive first unit bodies, and the low Ti-content aluminum-based solid solutions may be understood to refer to one or more consecutive second unit bodies.

[0048] The aluminum alloy core material for heat exchangers of the embodiment of the present disclosure has the following beneficial effects: The aluminum alloy core material for heat exchangers of the embodiment of the present disclosure includes an aluminum-based solid solution with a high Ti content and an aluminum-based solid solution with a low Ti content, the average value of the Ti content of the aluminum-based solid solution with a high Ti content is more than four times the nominal value of the Ti content of the aluminum alloy core material, and the average value of the Ti content of the aluminum-based solid solution with a low Ti content is less than 0.02%, and due to the difference in micro-components, a sufficiently large difference in micro-corrosion potential is formed, and such a difference is particularly retained in the hot processing process such as hot extrusion tube making and heat exchanger brazing, and finally distributed in alternating bands in the thickness direction of the heat exchange tube, and the corrosion form is band-like, which enables the corrosion in the thickness direction of the heat exchange tube to be suppressed, thereby effectively improving the pitting corrosion resistance of the heat exchange tube.

[0049] In some embodiments, the first unit body at least partially overlaps with at least one second unit body in an orthogonal projection onto a first plane or a second plane, the first plane being a plane parallel to a horizontal plane and the second plane being a plane that forms an angle α with the first plane, where 0°<α≦90°.

[0050] In some embodiments, the aluminum alloy material has a Ti content of 0.10-0.20%, more preferably 0.14-0.18%, calculated as a mass percentage.

[0051] In some embodiments, the aluminum alloy material has a Cu content of 0% when calculated by mass percentage. <Cu≦0.35%である。

[0052] In some embodiments, the aluminum alloy material has a Zn content of 0% when calculated by mass percentage. <Zn≦3.0%である。

[0053] In some embodiments, the aluminum alloy material has a Zr content of 0% calculated by mass percentage. <Zr≦0.4%である。

[0054] In some embodiments, the aluminum alloy material has a V content of 0% calculated by mass percentage. <V≦0.4%である。

[0055] In some embodiments, the aluminum alloy material has a Cr content of 0% calculated by mass percentage. <Cr≦0.5%である。

[0056] In some embodiments, the content of RE in the aluminum alloy material is 0% when calculated by mass percentage. <RE≦0.5%である。

[0057] In some embodiments, in the aluminum alloy material, the single content of unavoidable impurity elements is ≦0.05%, and the total content is ≦0.15%, calculated by mass percentage.

[0058] In some embodiments, in the grain structure of the aluminum alloy core material, when calculated by the number of grains, the proportion of equiaxed grains is 90% or more, and the maximum size of at least 40% of the equiaxed grains exceeds 100 μm. Since the grain size of the aluminum alloy core material affects the pitting corrosion resistance of the later-processed pipe material, the aluminum alloy core material in the embodiments of the present disclosure is mainly equiaxed, with grain sizes concentrated on the order of hundreds of μm, and when calculated by the number of grains, the proportion of grains with a size exceeding 100 μm exceeds 40%.

[0059] In some embodiments, the aluminum alloy core material is mixed with diffusely distributed second phase particles, and the maximum size of at least 90% of the second phase particles is less than 15 μm when calculated by the number of second phase particles. Mn, Fe, Si, Ti and impurity elements in the aluminum alloy material form second phase particles in the aluminum alloy core material, and the dispersed second phase particles can effectively improve the strength of the aluminum alloy core material, but the second phase particles with too large size will reduce the extrusion processing performance of the aluminum alloy core material. Considering all of this, the maximum size of at least 90% of the second phase particles (calculated by the number of second phase particles) in the aluminum alloy core material of the embodiments of the present disclosure is less than 15 μm.

[0060] Another aspect of the present disclosure provides a method for producing the aluminum alloy core material for heat exchangers, comprising the steps of: weighing and mixing the aluminum alloy material according to its components and weight percentages, and then performing semi-continuous casting and homogenization to produce an aluminum alloy core material, where the homogenization temperature is 550°C to 630°C and the homogenization time is 1h to 8h; preferably, the homogenization temperature is 580°C to 620°C and the homogenization time is 4h to 6h.

[0061] The manufacturing method of the aluminum alloy core material for heat exchangers in the embodiment of the present disclosure has the following beneficial effects: By controlling the composition and mass percentage of the alloying elements, as well as the temperature and time of the homogenization treatment, the manufactured aluminum alloy core material contains an aluminum-based solid solution with a high Ti content and an aluminum-based solid solution with a low Ti content, the average value of the Ti content of the aluminum-based solid solution with a high Ti content is more than four times the nominal value of the Ti content of the aluminum alloy core material, and the average value of the Ti content of the aluminum-based solid solution with a low Ti content is less than 0.02%, and the large difference distribution of the Ti content is the basis of the pitting corrosion resistance effect of the hot extrusion pipe material in the present disclosure.

[0062] In some embodiments, the manufacturing method of the aluminum alloy core material for heat exchanger includes the following steps: aluminum alloy material is weighed and mixed according to its components and weight percentages, put into a melting furnace and melted at 750°C-780°C, then refined in a holding furnace at 740°C-750°C, degassed with high purity Ar, and the hydrogen content of the aluminum alloy liquid after degassing is controlled to 0.13ml / 100g or less (preferably 0.10ml / 100g or less), then add 0.01%-0.03% by mass of Al-5 Ti-1 B grain refiner to the aluminum alloy liquid, perform two-stage filtration, cast after filtration, cast temperature is 705°C-715°C, and homogenization treatment is performed after casting, homogenization temperature is 550°C-630°C, and homogenization time is 1h-8h.

[0063] Another aspect of an embodiment of the present disclosure further provides a heat exchange tube including a tube wall and at least one heat exchange passage, the heat exchange passage extending in a longitudinal direction of the heat exchange tube, and a core material surrounding the tube wall of the heat exchange passage includes the aluminum alloy core material described above.

[0064] The aluminum-based solid solution having a high Ti content and the aluminum-based solid solution having a low Ti content alternately distributed in the aluminum alloy core material in the embodiment of the present disclosure are formed into bands approximately parallel to the direction of the tube wall after being manufactured into a heat exchange tube by processing, and are alternately distributed in the thickness direction of the tube wall. It may be understood that the aluminum-based solid solution having at least a high Ti content and the aluminum-based solid solution having a low Ti content alternately distributed are at least partially overlapped in projection on a projection plane perpendicular to the thickness direction of the heat exchange tube.

[0065] The heat exchange tube of the embodiment of the present disclosure has the following beneficial effects: the aluminum-based solid solution with high Ti content and the aluminum-based solid solution with low Ti content alternately distributed in the original aluminum alloy core material after hot extrusion are formed into bands parallel to the tube wall direction, which forms a potential gradient that is alternately distributed microscopically on the tube wall, and such an alternately distributed potential gradient can confine corrosion within the low potential band, and only after the low potential band is consumed can corrosion break through the high potential band and spread to the inside of the tube, which can effectively improve the pitting corrosion resistance of the heat exchange tube.

[0066] In some embodiments, the heat exchange tube is manufactured by subjecting the aluminum alloy core material to an extrusion process, and the extrusion ratio of the extrusion process is greater than or equal to 50. When the heat exchange tube is a micro-channel flat tube, the extrusion ratio is greater than or equal to 150. In order to better crush and disperse the second phase particles and to densify the microstructure of the tube material, the extrusion ratio in the extrusion process needs to be greater than or equal to 50, and the extrusion ratio of the micro-channel flat tube is preferably greater than or equal to 150.

[0067] In some embodiments, the heat exchange tube includes a solder layer, the solder layer being an Al-Si based alloy, the solder layer forms a diffusion layer by silicon diffusion during the brazing process, and the thickness of the diffusion layer is less than 20% of the thickness of the tube wall.

[0068] In the brazing process of heat exchanger products with a welded structure, the Si element in the solder layer diffuses into the heat exchange tube, and with the local dissolution of the heat exchange tube base material, the diffusion of Si is faster and deeper, especially at the grain boundary positions of the heat exchange tube, than at non-grain boundary positions. The diffusion of Si into the tube material changes the components of the tube material, especially the components at the grain boundary positions of the tube material where diffusion is more, and has a negative effect on the corrosion resistance of the tube material. In order to reduce this negative effect, it is necessary to effectively control the diffusion depth of Si in the solder layer into the tube material, and it is preferable that it is 20% or less of the thickness of the tube wall of the heat exchange tube (generally 20 μm or less).

[0069] Another aspect of an embodiment of the present disclosure further provides a heat exchanger including the heat exchange tube described above. The heat exchanger of the embodiment of the present disclosure has the following beneficial effects: Since the above heat exchange tube is adopted, the service life of the heat exchanger is greatly improved.

[0070] In some embodiments, the heat exchanger includes a first tube, a second tube, and a heat exchange tube. A plurality of said heat exchange tubes are spaced apart along a length of a first tube, the heat exchange tube including a heat exchange passage extending along its length, the plurality of heat exchange passages being spaced apart across the width of the heat exchange tube, the heat exchange tube being connected directly or indirectly to the first tube, and the heat exchange tube being connected directly or indirectly to the second tube.

[0071] In some embodiments, the heat exchanger further comprises fins. The fins are connected to the heat exchange tubes, and some of the fins are located between two adjacent heat exchange tubes in the longitudinal direction of the first tube, and the fins are multiple; The material of the fins is an aluminum alloy, and the corrosion potential of the fins is equal to or lower than the corrosion potential of the heat exchange tubes.

[0072] In some embodiments, the surface of the heat exchange tube is arc-sprayed with zinc or pre-coated with a zinc-containing flux. The Zn element is added to an aluminum alloy to reduce the corrosion potential of the aluminum alloy. Since Zn has a large solid solubility in an aluminum alloy, Zn, except for reacting with other alloy elements to form a second phase, is usually present in the form of a solid solution in an aluminum alloy. When the dissolved Zn exhibits a distribution from high concentration to low concentration from the surface layer to the inner layer of the heat exchange tube, the distribution of the corrosion potential from low to high from the surface layer to the inner layer of the heat exchange tube can effectively improve the pitting corrosion resistance performance of the aluminum alloy heat exchange tube. The zinc pre-arranged on the surface of the heat exchange tube during welding heating diffuses from the surface to the inside to form a concentration gradient, thereby effectively extending the corrosion resistance life of the heat exchange tube. In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solution in the embodiments of the present invention. In the specific embodiments, the specific conditions are not specified, and the general conditions are followed.

[0073] Example 1 Al99.90, AlFe10, AlMn20, and AlTi10 were weighed and mixed according to the mass percentage of the alloy components in Table 1, put into a melting furnace and melted at 750 ° C ~ 780 ° C, then refined at 740 ° C ~ 750 ° C in a holding furnace, degassed using high purity Ar, and the hydrogen content of the aluminum alloy liquid after degassing was controlled to 0.10 ml / 100 g or less, and then 0.02% of Al ~ 5 Ti ~ 1 B grain refiner was added to the aluminum alloy liquid, two-stage filtration was performed, and semi-continuous casting was performed after filtration, and the aluminum rod with a diameter of 203 mm was cast at a casting temperature of 705 ° C ~ 715 ° C. The aluminum rod after casting was subjected to homogenization treatment, the homogenization treatment temperature was 595 ° C ~ 605 ° C, and the homogenization time was 4 h. The homogenized ingot was cut off at both ends and saw cut to the required length. Before extrusion, the ingot zone was preheated in stages, the ingot preheating temperature was 490℃~510℃, the extrusion die temperature was 460℃~500℃, and hot extrusion processing was performed using a die that can make six products in one process, and the extrusion speed of the tube was 40~130m / min to obtain an extruded tube.

[0074] Examples 2 to 9 The alloy components and mass percentages of Examples 2 to 9 are shown in Table 1. The alloy element Zn was mixed at Zn99.95, and the alloy element Cu was mixed at AlCu50. The manufacturing process of the extruded pipe was the same as that of Example 1.

[0075] Comparative Examples 1 to 4 The alloy components and mass percentages of Comparative Examples 1 to 4 are shown in Table 1. The alloy element Zn was weighed and mixed at Zn99.95, the alloy element Cu was weighed and mixed at AlCu50, and the manufacturing process for the extruded pipe was the same as in Example 1.

[0076] The extruded tube has a width of 16 mm, a thickness of 1.3 mm, 16 inner holes, and a tube wall thickness of 0.28 mm.

[0077] Extrusion performance was classified as excellent, medium, or poor.

[0078] The corrosion resistance test of extruded pipe (zinc-free pipe, i.e., no zinc spray treatment on the surface of the extruded pipe) is performed on the extruded pipe that has undergone a simulated brazing heat cycle, the peak temperature of the simulated brazing is 600°C, and the temperature is kept at the peak temperature for 2min-3min. The corrosion test is performed according to the SWAAT of the ASTM G85 standard, the salt solution is a simulated mixed sea salt with a concentration of 4.2g / L, the pH value of the solution is adjusted to 2.8-3.0 with acetic acid, the saturator temperature is set to 57°C, the housing temperature is set to 49°C, and the test cycle is 30 minutes of spraying + 90 minutes of moisture retention above 98%RH. The corrosion penetration time is shown in Table 1.

[0079] Table 1. Composition (mass%) and performance of alloys in examples and comparative examples

[0080] [Table 1] Table 2. Mechanical properties of alloys of the examples and comparative examples [Table 2]

[0081] As can be seen from Tables 1 and 2, the corrosion resistance of the alloys of the embodiments of the present disclosure is generally superior to that of conventional pipe alloys, and the strength of the alloys is similar to that of conventional pipe alloys. The alloys of the embodiments of the present disclosure are adopted to improve the corrosion resistance of the alloys, while the extrusion processing performance and tubular dimensional design of the alloys are close to those of the comparative alloys.

[0082] FIG. 1a is an SEM image of a grain at a central position (center and vicinity of the circle of the circular cross section, the same below), FIG. 1b is an SEM image of a grain at a 1 / 4 position in the radial direction (middle position and vicinity of the radius of the circular cross section, the same below), FIG. 1c is an SEM image of a second phase particle at the central position, FIG. 1d is an SEM image of a second phase particle at a 1 / 4 position in the radial direction, FIG. 1e is an EDS image of the Ti element content at the central position, and FIG. 1f is an EDS image of the Ti element content at a 1 / 4 position in the radial direction. As can be seen from FIGS. 1a to 1f, the ingot after homogenization is mainly equiaxed crystals, and the average grain size is larger than 100 μm (at least 40% (calculated by number) of the grains have a maximum size larger than 100 μm). The second phase particles of the ingot after homogenization are fine, some of the second phase particles are concentrated at the grain boundaries, and the proportion of second phase particles with a size of more than 15 μm is less than 10% (calculated by number). The Ti content at some positions of the ingot after homogenization reaches 0.74% and 1.25%, which is four times the nominal value of 0.64%, while Ti at some positions is almost undetectable, and such a large difference distribution of Ti content is the ingot basis for the beneficial pitting corrosion resistance effect of the extruded tube of the present disclosure.

[0083] The SEM images of the crystal particles and second phase particles of the extruded tube of Example 1 (randomly sampled on the wall of the extruded tube, and the same applies below) are shown in Figures 2a to 2b, where Figure 2a is an SEM image of the crystal particles of the extruded tube, and Figure 2b is an SEM image of the second phase particles of the extruded tube. It can be seen that the average size of the crystal particles in the extruded tube is about 50 μm, and the second phase particles after extrusion tend to be distributed along the extrusion processing direction.

[0084] 3a to 3c show the extruded pipe (zinc-free pipe) and the zinc-sprayed pipe (the extruded pipe was subjected to surface zinc spraying treatment and then arc-sprayed with 8±2 g / m 2 ), and zinc sprayed tube after simulated brazing (zinc sprayed tube is subjected to simulated brazing treatment, the peak temperature of the simulated brazing is 600℃, and the temperature is kept at the peak temperature for 2min~3min). Figure 3a is a typical corrosion morphology diagram of the zinc sprayed tube after simulated brazing after 4000h SWAAT, Figure 3b is a typical corrosion morphology diagram of the zinc sprayed tube after 3000h SWAAT, and Figure 3c is a typical corrosion morphology diagram of the zinc-free tube after 4000h SWAAT. It can be seen that unlike general pitting corrosion, the corrosion of the tube material tends to progress in a multi-stage lateral direction, which improves the pitting corrosion resistance of the tube material and effectively extends the corrosion resistance life of the tube material.

[0085] The SEM images of the grains and the second phase and the EDS detection results of the Ti element content at typical positions of the ingot after homogenization in Example 2 are shown in Figures 4a to 4f. Figure 4a is an SEM image of a grain at the center, Figure 4b is an SEM image of a grain at 1 / 4 of the radial position, Figure 4c is an SEM image of a second phase particle at the center, Figure 4d is an SEM image of a second phase particle at 1 / 4 of the radial position, Figure 4e is an EDS image of the Ti element content at the center, and Figure 4f is an EDS image of the Ti element content at 1 / 4 of the radial position. It can be seen that the ingot after homogenization is mainly equiaxed crystals, and the average grain size is slightly larger than 100 μm (the maximum size of at least 40% (calculated by number) of the grains is larger than 100 μm). The second phase particles of the ingot after homogenization are fine, some of the second phase particles are concentrated at the grain boundaries, and the proportion of second phase particles with a size of more than 15 μm is less than 10% (calculated by number). The Ti content of some positions of the ingot after homogenization reaches 0.49%, exceeding the nominal value of 0.4%, which is four times, while Ti at some positions is almost undetectable. Such a large difference distribution of Ti content is the ingot basis for the beneficial pitting corrosion resistance effect of the extruded tube of the present disclosure.

[0086] The SEM images of the crystal grains and second phase particles of the extruded tube of Example 2 are shown in Figures 5a to 5b. Figure 5a is an SEM image of the crystal grains of the extruded tube, and Figure 5b is an SEM image of the second phase particles of the extruded tube. It can be seen that the crystal grains of the extruded tube have a typical mixed grain structure, and the second phase particles after extrusion tend to be distributed along the extrusion processing direction.

[0087] 6a to 6b show an extruded pipe (zinc-free pipe) manufactured in Example 2, a zinc-sprayed pipe after simulated brazing (an extruded pipe that was subjected to surface zinc spraying treatment and arc-sprayed with 8±2 g / m 2 6a shows a typical corrosion morphology diagram of the zinc sprayed tube after 4000h SWAAT, and FIG. 6b shows a typical corrosion morphology diagram of the zinc sprayed tube after 2000h SWAAT. Unlike general pitting corrosion, the corrosion of the tube material tends to progress in a multi-stage lateral direction, which improves the pitting corrosion resistance of the tube material and effectively extends the corrosion resistance life of the tube material.

[0088] The SEM diagrams of the grains and the second phase and the EDS detection results of the Ti element content at typical positions of the ingot after homogenization in Example 4 are shown in Figures 7a to 7f, where Figure 7a is an SEM diagram of the grains at the center position, Figure 7b is an SEM diagram of the grains at the 1 / 4 position in the radial direction, Figure 7c is an SEM diagram of the second phase particle at the center position, Figure 7d is an SEM diagram of the second phase particle at the 1 / 4 position in the radial direction, Figure 7e is an EDS diagram of the Ti element content at the center position, and Figure 7f is an EDS diagram of the Ti element content at the 1 / 4 position in the radial direction. It can be seen that the ingot after homogenization is mainly equiaxed crystals, with the average grain size being greater than 100 μm (at least 40% (calculated by number) of the grains have a maximum size greater than 100 μm). The second phase particles of the ingot after homogenization are fine, some of the second phase particles are gathered at the grain boundaries, and the proportion of second phase particles with a size greater than 15 μm is less than 10% (calculated by number). After homogenization, the Ti content at some positions of the ingot reaches 0.77% and 1.24%, exceeding the nominal value of 0.56%, which is four times higher, while Ti at some positions is barely detectable. Such a large difference distribution of Ti content is the ingot basis for the beneficial pitting corrosion resistance effect of the extruded tube of the present disclosure.

[0089] The SEM images of the crystal grains and second phase particles of the extruded tube of Example 4 are shown in Figures 8a-8b. Figure 8a is an SEM image of the crystal grains of the extruded tube, and Figure 8b is an SEM image of the second phase particles of the extruded tube. It can be seen that the average size of the crystal grains of the extruded tube is about 50 μm, and the second phase particles after extrusion tend to be distributed along the extrusion processing direction.

[0090] The zinc-sprayed pipe manufactured in Example 4 (the extruded pipe was subjected to surface zinc spraying treatment, and the arc zinc spraying was performed at 8±2 g / m 2 ) are shown in Figures 9a-9b, where Figure 9a shows a typical corrosion morphology of a zinc sprayed tube after 4000h of SWAAT, and Figure 9b shows a typical corrosion morphology of a zinc sprayed tube after 6000h of SWAAT. Unlike general pitting corrosion, the corrosion of the tube material tends to progress in a multi-stage lateral direction, which improves the pitting corrosion resistance of the tube material and effectively extends the corrosion resistance life of the tube material.

[0091] An embodiment of the present disclosure further provides a heat exchanger employing the above heat exchange tube, as shown in FIG. 10 , comprising a first tube 1, a second tube 2, a heat exchange tube 3, and a fin 4, a plurality of the heat exchange tubes 3 are spaced apart along the longitudinal direction of the first tube 1, the heat exchange tube 3 comprises a heat exchange passage extending along its longitudinal direction, the plurality of heat exchange passages are spaced apart along the width direction of the heat exchange tube 3, the heat exchange tube 3 is directly or indirectly connected to the first tube 1, the heat exchange tube 3 is directly or indirectly connected to the second tube 2, the fins 4 are connected to the heat exchange tube 3, some of the fins 4 are located between two adjacent heat exchange tubes 3 in the longitudinal direction of the first tube 1, and the fins 4 are multiple.

[0092] In some particular embodiments, the heat exchange tubes 3 are flat tubes.

[0093] In some specific embodiments, the first tube 1 is a first header and the second tube 2 is a second header.

[0094] In some embodiments, the surface of the heat exchange tube 3 is pre-coated with zinc arc spraying or zinc-containing flux. When the heat exchange tube 3 is brazed to other assemblies of the heat exchanger, the zinc pre-disposed on the surface of the heat exchange tube diffuses from the surface to the inside to form a concentration gradient, i.e., a distribution from a low corrosion potential to a high corrosion potential from the surface layer to the inner layer of the heat exchange tube, thereby effectively extending the corrosion resistance life of the heat exchange tube.

[0095] The heat exchanger according to the embodiment of the present disclosure employs the above-mentioned heat exchange tube, so that the heat exchanger can withstand corrosion and has a long service life.

[0096] The alloy of Example 4 is selected, and after the flat tube is manufactured, the header and fin are combined to manufacture the heat exchanger (Y) and (F) shown in FIG. 10. The differences between the heat exchanger (Y) and (F) are as follows: The furnace welding of the core of the heat exchanger (Y) adopts higher furnace parameters than the heat exchanger (F), and the furnace temperature setting is 10°C higher than the heat exchanger (F). FIG. 11 shows the Si element diffusion situation of the typical flat tube near the header position in the finless area between the header and the fin in the heat exchanger (F) and the heat exchanger (F) detected by SEM&EDS. As can be seen from FIG. 11, the Si content of the flat tube surface layer near the header of the heat exchanger (Y) is obviously higher than that of the heat exchanger (F), and the Si diffusion depth of the flat tube in the heat exchanger (Y) is about 30 μm, while the Si diffusion depth of the flat tube in the heat exchanger (F) is about 20 μm. When using the SWAAT test with a box temperature of 49°C, the inlet and outlet pipes were protected with electrical tape during the test. Five heat exchanger samples had leakage in the flat tubes near the header after 2500 hours of testing, while five heat exchanger samples had no leakage after 3000 hours of testing.

[0097] In this disclosure, relational terms such as "first" and "second" are merely used to distinguish one entity or unit from another entity or unit, and do not necessarily require or imply that such an actual relation or order exists between these entities or units. In this specification, "multiple" means at least two, unless otherwise specified.

[0098] In the present disclosure, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, general expressions of the above terms do not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, unless mutually inconsistent, a person skilled in the art can combine or combine features of different embodiments or examples and different embodiments or examples described in this specification.

[0099] Although the embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are illustrative and should not be understood as limiting the present disclosure, and a person of ordinary skill in the art may make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. An aluminum alloy core material for a heat exchanger, comprising an aluminum alloy material, the aluminum alloy material contains, by mass percentage, 0.20-1.20% Mn, 0.08%-0.25% Fe, 0.08%-0.25% Ti, 0.03%-0.12% Si, 0-0.35% Cu, 0-3.0% Zn, 0-0.4% Zr, 0-0.4% V, 0-0.5% Cr, and 0-0.5% RE, with the remainder being aluminum and unavoidable impurities, the RE being a rare earth element; The aluminum alloy core material for heat exchangers comprises a plurality of first unit bodies, a plurality of second unit bodies and a plurality of third unit bodies, wherein the first unit bodies, the second unit bodies and the third unit bodies have the same volume, the average Ti content of the first unit bodies is four times or more the nominal Ti content of the aluminum alloy core material for heat exchangers, the average Ti content of the second unit bodies is less than 0.02%, and the average Ti content of the third unit bodies is greater than the average Ti content of the second unit bodies and smaller than the average Ti content of the first unit bodies.

2. The aluminum alloy core material for heat exchangers described in claim 1, characterized in that the first unit body and at least one of the second unit bodies at least partially overlap in orthogonal projection on a first plane or a second plane, the first plane is a plane parallel to a horizontal plane, and the second plane is a plane that forms an included angle α with the first plane, where α is 0°<α≦90°.

3. 2. The aluminum alloy core material for heat exchangers according to claim 1, wherein the Ti content is 0.10 to 0.20%.

4. The aluminum alloy core material for heat exchangers as described in claim 1, characterized in that in the crystal grain structure of the aluminum alloy core material for heat exchangers, when calculated by the number of crystal grains, the proportion of equiaxed crystals is 90% or more, and the maximum size of at least 40% of the equiaxed crystal grains exceeds 100 μm.

5. The aluminum alloy core material for heat exchangers according to claim 1, characterized in that the aluminum alloy core material for heat exchangers contains diffusely distributed second phase particles, and when calculated based on the number of the second phase particles, the maximum size of at least 90% of the second phase particles is less than 15 μm.

6. A method for producing an aluminum alloy core material for a heat exchanger, the aluminum alloy core material for a heat exchanger being the aluminum alloy core material for a heat exchanger according to any one of claims 1 to 5, The manufacturing method includes the steps of weighing and mixing the aluminum alloy material according to the components and weight percentages of the aluminum alloy material, and then performing semi-continuous casting and homogenization treatment to manufacture the aluminum alloy core material for heat exchangers, wherein the homogenization treatment temperature is 550°C to 630°C, and the homogenization treatment time is 1h to 8h.

7. A heat exchange tube comprising a tube wall and at least one heat exchange passage, the heat exchange passage extending in a longitudinal direction of the heat exchange tube, the heat exchange passage being surrounded by the tube wall, and a core material of the tube wall comprising the aluminum alloy core material according to any one of claims 1 to 5.

8. The heat exchange tube according to claim 7, wherein the heat exchange tube is manufactured by a method including an extrusion process using the aluminum alloy core material according to any one of claims 1 to 5, and an extrusion ratio of the extrusion process is 50 or more.

9. The heat exchange tube according to claim 7 or 8, characterized in that the heat exchange tube includes a solder layer, the solder layer being an Al-Si based alloy, the solder layer forms a diffusion layer by silicon diffusion during a brazing process, and the thickness of the diffusion layer is 20% or less of the thickness of the tube wall.

10. A heat exchanger comprising a heat exchange tube according to any one of claims 7 to 9, the heat exchanger includes a first tube, a second tube, and a heat exchange tube; a plurality of said heat exchange tubes spaced apart along a longitudinal direction of said first tube, said heat exchange tube including a heat exchange passage extending along said longitudinal direction, said plurality of said heat exchange passages spaced apart across a width of said heat exchange tube, said heat exchange tube being connected directly or indirectly to said first tube, and said heat exchange tube being connected directly or indirectly to said second tube.

11. The heat exchanger further includes fins, the fins being connected to the heat exchange tubes; Some of the fins are located between two adjacent heat exchange tubes in the longitudinal direction of the first tube, and the fins are multiple; 11. The heat exchanger according to claim 10, wherein the material of the fins is an aluminum alloy, and the corrosion potential of the fins is equal to or lower than the corrosion potential of the heat exchange tubes.

Images