CN118616961A

CN118616961A - Aluminum alloy brazing composite material and preparation method and application thereof

Info

Publication number: CN118616961A
Application number: CN202410862289.1A
Authority: CN
Inventors: 廖永启; 伍波; 高勇进; 谢永林; 聂存珠; 刘挺; 梁斌; 唐劲松
Original assignee: Shanghai Huafon Aluminum Corp
Current assignee: Shanghai Huafon Aluminum Corp
Priority date: 2024-06-28
Filing date: 2024-06-28
Publication date: 2024-09-10

Abstract

The invention provides an aluminum alloy brazing composite material, a preparation method and application thereof, wherein the aluminum alloy brazing composite material comprises a pre-buried brazing flux composite layer and a core layer; the embedded brazing flux composite layer comprises a middle layer and a surface layer arranged on the middle layer, and the middle layer is arranged close to the core layer; the intermediate layer comprises aluminum-silicon alloy pre-embedded with brazing flux, and the liquidus temperature of the aluminum-silicon alloy in the intermediate layer is not more than 620 ℃. Compared with the conventional brazing flux spraying product process, the brazing flux spraying method can greatly reduce the residual quantity of the brazing flux, and the client can realize brazing without any process and equipment adjustment, so that the brazing flux spraying method has a wider application prospect.

Description

Aluminum alloy brazing composite material and preparation method and application thereof

Technical Field

The invention relates to the technical field of metal materials, in particular to an aluminum alloy brazing composite material, a preparation method and application thereof.

Background

The aluminum alloy composite brazing material is widely applied to heat exchanger products such as automobiles, civil and commercial air conditioners, engineering machinery and the like, such as automobile engine radiators, engine oil coolers, civil and commercial air conditioner condensers and evaporators, engineering machinery intercoolers and the like. After the solder layer of the aluminum alloy composite material is melted by high-temperature brazing, metal metallurgical bonding is formed among all parts of the heat exchanger through capillary action, so that various heat exchanger products with different functions are manufactured.

Because the surface of the aluminum alloy is provided with a layer of compact oxide film which can prevent the melting and flowing of the brazing flux layer, products are generally subjected to pre-spraying brazing flux (brazing flux, soldering flux) before brazing, such as nocolok brazing flux. The brazing flux can damage the oxide film in advance in the brazing process, so that the brazing thin layer is guaranteed to be fully melted, the fluidity of the brazing thin layer is improved, and the welding quality is guaranteed. However, the flux remains on the surface of the heat exchanger, which not only affects the appearance and cleanliness of the product, but also causes adverse reaction with the automobile coolant in some cases, so that the coolant is deteriorated. In particular, in the field of new energy automobiles, due to the large amount of applications of electromagnetic expansion valves and hydrogen fuel cells, the heat exchanger has higher and higher requirements on the cleanliness of products and the residual granularity of particles on the surfaces of the products.

The vacuum brazing technology can enable the heat exchanger to realize brazing flux-free brazing, and solves the problem of product cleanliness. However, vacuum brazing needs to be performed in a high vacuum environment, and has low brazing efficiency, high cost and limited application and popularization.

Disclosure of Invention

In order to solve the technical problems, the invention provides the aluminum alloy brazing composite material, the preparation method and the application thereof, and the brazing flux is pre-buried in the composite layer in advance, so that the residual amount of the brazing flux can be reduced, and the brazing can be realized without adjusting the process and equipment, thereby having wide application prospect.

To achieve the purpose, the invention adopts the following technical scheme:

In a first aspect, the present invention provides an aluminum alloy brazing composite material comprising a pre-buried flux composite layer and a core layer;

The embedded brazing flux composite layer comprises a middle layer and a surface layer arranged on the middle layer, and the middle layer is arranged close to the core layer;

The intermediate layer comprises aluminum-silicon alloy pre-embedded with brazing flux, and the liquidus temperature of the aluminum-silicon alloy in the intermediate layer is not more than 620 ℃, for example, 620℃、619℃、618℃、617℃、616℃、615℃、614℃、613℃、612℃、611℃、610℃、609℃、608℃、607℃、606℃、605℃、604℃、603℃、602℃、601℃、600℃、599℃、598℃、597℃、596℃、595℃、594℃、592℃、590℃、580℃、570℃、560℃、550℃ or 540 ℃ and the like.

According to the invention, an ideal welding seam filling effect can be obtained under the brazing condition by adopting the pre-buried brazing flux composite layer, and the liquidus temperature of the aluminum-silicon alloy in the middle layer is further limited to be not more than 620 ℃, and if the liquidus is too high, the brazing temperature is higher, so that the material corrosion or the core material overburning can be reduced.

Preferably, the mass percentage of the brazing flux in the intermediate layer is 1-20%, for example, 1%, 4%, 5%, 5.5%, 6%, 7%, 8%, 9%, 9.5%, 10%, 10.5%, 11%, 12%, 12.5%, 13%, 14%, 15%, 15.5%, 16%, 16.5%, 17%, 18%, 19% or 20%, etc., but not limited to the recited values, and other non-recited values in this range are equally applicable.

The mass percent of the brazing flux in the invention determines the welding quality, the difficulty of mixing the brazing flux with the aluminum silicon powder and the brazing flux residue, and the brazing flux residue after brazing and the difficulty of mixing the aluminum silicon powder are increased too much, and the brazing quality is reduced too little. The higher the brazing flux percentage content is, the lower the composite ratio of the aluminum-silicon alloy pre-embedded with the brazing flux is, so that the brazing flux content is generally ensured, the waste is avoided, and the brazing quality of a client can be met.

Preferably, the size D90.ltoreq.70 μm and D50.ltoreq.20 μm of the flux in the intermediate layer, wherein D90 may be, for example, 40 μm, 44 μm, 45 μm, 46 μm, 47 μm, 49 μm, 50 μm, 52 μm, 54 μm, 55 μm, 57 μm, 60 μm, 64 μm, 65 μm, 67 μm or 70 μm, etc., but is not limited to the values recited, other non-recited values within this range being equally applicable; the D50 may be, for example, 1 μm,2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm, etc., but is not limited to the recited values, and other values not recited in the range are equally applicable.

The oversized brazing flux can lead to uneven mixing of brazing flux powder and aluminum silicon powder and even incomplete fusion, and can reduce the processability of the layer of material and influence the final welding quality of the material.

The core layer may be an aluminum-magnesium-silicon alloy, and the Mg element content is generally higher than 0.3%, for example: mg was 0.87% and Si was 0.59%. When the core layer is made of aluminum-magnesium-silicon alloy, a blocking layer is required to be arranged between the embedded brazing flux composite layer and the core layer so as to prevent Mg element from diffusing into the embedded brazing flux composite layer and reacting with the brazing flux.

Preferably, the core layer is an aluminum manganese alloy.

Preferably, the core layer comprises, in mass percent: si is less than or equal to 1%, fe is less than or equal to 0.7%, cu is less than or equal to 1.0%, mn is less than or equal to 0.9% and less than or equal to 1.82%, mg is less than or equal to 0.3%, and the solidus temperature of the aluminum-manganese alloy is not lower than 605 ℃.

The Si content may be 0.01％、0.07％、0.12％、0.17％、0.22％、0.28％、0.33％、0.38％、0.43％、0.48％、0.54％、0.59％、0.64％、0.69％、0.74％、0.8％、0.85％、0.9％、0.95 or 1, for example, but is not limited to the values recited, and other values not recited in the range are equally applicable.

The Fe content may be 0.01％、0.05％、0.09％、0.12％、0.16％、0.2％、0.23％、0.27％、0.31％、0.34％、0.38％、0.41％、0.45％、0.49％、0.52％、0.56％、0.6％、0.63％、0.67 or 0.7, for example, but is not limited to the values recited, and other values not recited in this range are equally applicable.

The Cu content may be 0.01％、0.07％、0.12％、0.17％、0.22％、0.28％、0.33％、0.38％、0.43％、0.48％、0.54％、0.59％、0.64％、0.69％、0.74％、0.8％、0.85％、0.9％、0.95 or 1, for example, but is not limited to the values recited, and other values not recited in the range are equally applicable.

The Mn content may be 0.90％、0.95％、1％、1.05％、1.1％、1.15％、1.2％、1.24％、1.29％、1.34％、1.39％、1.44％、1.49％、1.53％、1.58％、1.63％、1.68％、1.73％、1.78 or 1.82, for example, but is not limited to the values recited, and other values not recited in the range are equally applicable.

The Mg content may be 0.01％、0.03％、0.05％、0.06％、0.08％、0.09％、0.11％、0.12％、0.14％、0.15％、0.17％、0.18％、0.2％、0.21％、0.23％、0.24％、0.26％、0.27％、0.29％ or 0.3%, for example, but is not limited to the values recited, and other values not recited in this range are equally applicable. When the Mg content is less than or equal to 0.3%, the influence of Mg element in the core material on the composition of the soldering flux in the pre-buried soldering flux composite layer is small, and a blocking layer can be added or not added according to the soldering condition.

The average grain size of the core layer after brazing is preferably 20 to 2000 μm, and may be 20μm、125μm、220μm、330μm、430μm、540μm、640μm、750μm、850μm、950μm、1060μm、1160μm、1270μm、1375μm、1470μm、1580μm、1680μm、1790μm、1890μm or 2000 μm, for example, but not limited to the values recited, and other values not recited in the range are equally applicable.

Preferably, the surface layer is an aluminum-silicon alloy, and the liquidus temperature of the aluminum-silicon alloy in the surface layer is not more than 620 ℃, for example, 450 ℃, 459 ℃, 468 ℃, 477 ℃, 486 ℃, 495 ℃, 504 ℃, 513 ℃, 522 ℃, 531 ℃, 540 ℃, 549 ℃, 558 ℃, 567 ℃, 576 ℃, 585 ℃, 594 ℃, 603 ℃, 612 ℃, 620 ℃ or the like, but not limited to the recited values, and other non-recited values within the range are equally applicable.

Preferably, the intermediate layer and the surface layer each independently comprise Si in mass percent: the content of 6% to 13% may be, for example, 6%, 6.4%, 6.8%, 7.2%, 7.5%, 7.9%, 8.3%, 8.6%, 9%, 9.4%, 9.7%, 10.1%, 10.5%, 10.8%, 11.2%, 11.6%, 11.9%, 12.3%, 12.7% or 13%, etc., but the present invention is not limited to the above-mentioned values, and other values not mentioned in the above range are equally applicable.

Preferably, the pre-buried brazing flux composite layer is arranged on two sides or one side of the core layer.

Preferably, the thickness of the pre-buried brazing flux composite layer monolayer is 1-30% of the thickness of the aluminum alloy brazing composite material, for example, 1%, 3%, 5%, 6%, 8%, 9%, 11%, 12%, 14%, 15%, 17%, 18%, 20%, 21%, 23%, 24%, 26%, 27%, 29% or 30%, etc., but not limited to the recited values, and other non-recited values within the range are equally applicable.

Preferably, the total thickness of the pre-buried brazing flux composite layer is less than or equal to 40% of the thickness of the aluminum alloy brazing composite material, for example, 20%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%, etc., but not limited to the recited values, and other non-recited values within the range are equally applicable.

Preferably, the thickness of the intermediate layer on one side accounts for 0.5 to 5% of the thickness of the aluminum alloy brazing composite material, and may be, for example, 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.7%, 2%, 2.2%, 2.4%, 2.7%, 2.9%, 3.2%, 3.4%, 3.6%, 3.9%, 4.1%, 4.3%, 4.6%, 4.8% or 5%, etc., but not limited to the recited values, and other non-recited values within this range are equally applicable.

The thickness of the pre-buried brazing flux composite layer in the invention has the following effect: as a braze layer/filler alloy of the entire material, providing solder after brazing forms a welded joint, too low results in poor brazing of the material, and too high results in solder overflow or erosion. The brazing flux is contained in the middle layer, so that oxidation breakage can be eliminated in the brazing process, the wettability and filling performance of the solder are improved, and the welding quality is ensured. Too low a thickness may result in insufficient oxide film removal, poor brazing, too much thickness may result in too much flux and too much residual.

The aluminum alloy brazing composite material can be brazed with other materials to form a good welding joint under the condition that external brazing flux is not needed.

Preferably, the thickness of the surface layer is equal to or greater than the thickness of the intermediate layer.

Preferably, the thickness of the aluminum alloy brazing composite material is 0.05-5.0 mm, for example 0.05mm、0.32mm、0.58mm、0.84mm、1.1mm、1.36mm、1.62mm、1.88mm、2.14mm、2.4mm、2.66mm、2.92mm、3.18mm、3.44mm、3.7mm、3.96mm、4.22mm、4.48mm、4.74mm mm or 5.0mm, etc., but not limited to the recited values, other non-recited values within this range are equally applicable.

Preferably, the yield strength of the aluminum alloy brazing composite material after brazing is not lower than 40MPa and the tensile strength is not lower than 120MPa, wherein the yield strength can be, for example, 40MPa, 42MPa, 43MPa, 45MPa, 47MPa, 48MPa, 50MPa, 51MPa, 53MPa, 54MPa, 56MPa, 58MPa, 59MPa, 61MPa, 62MPa, 64MPa or 65MPa, and the like, but is not limited to the recited values, and other non-recited values in the range are equally applicable. The tensile strength is not lower than 120MPa, and may be 120MPa、121MPa、124MPa、126MPa、129MPa、132MPa、134MPa、137MPa、139MPa、142MPa、145MPa、147MPa、150MPa、153MPa、155MPa、158MPa or 160MPa, for example, but is not limited to the values recited, and other values not recited in the range are equally applicable.

Preferably, the aluminum alloy brazing composite material has a post-weld potential of not less than-750 mV.

In a second aspect, the present invention provides a method for preparing the aluminum alloy brazing composite material according to the first aspect, the method comprising the steps of:

The core layer and the surface layer are respectively and independently smelted and cast in turn to prepare a billet, and the middle layer is prepared into a billet through aluminum containing brazing flux particles or aluminum alloy containing brazing flux particles;

The billets are made into plates according to the thickness and are compounded to form an aluminum alloy brazing composite material;

The composite plate is subjected to hot rolling, cold rolling and annealing processes sequentially to obtain the aluminum alloy brazing composite material.

Specifically, the aluminum alloy brazing composite material is subjected to hot rolling, cold rolling and annealing in sequence, and corresponding parameters are adjusted to obtain a brazing sheet in H24 state or O state, wherein the adjustment of H24 state or O state is a technology well known to a person skilled in the art, and an annealing temperature is generally higher than that required for obtaining H24 state, and is not described in detail herein.

The aluminum alloy brazing composite material is subjected to hot rolling, cold rolling, annealing and cold rolling in sequence, and the corresponding parameters are adjusted to obtain a brazing sheet in H14 state, wherein the adjustment of H14 state is a technology well known to a person skilled in the art and is not described in detail herein.

The aluminum alloy brazing composite material is subjected to hot rolling, intermediate annealing, cold rolling and annealing in sequence, and corresponding parameters are adjusted to obtain an O-state or H24-state brazing sheet, wherein the adjustment of the O-state or H24-state is a technology well known to a person skilled in the art, and the detailed description is omitted herein. Intermediate annealing can be added between the cold rolling after the hot rolling, and the H14 can be obtained by adjusting corresponding parameters.

The manner in which the intermediate layer is formed into a billet in the present invention includes, but is not limited to, using any one or a combination of at least two of hot isostatic pressing, cold isostatic pressing, spray forming, thermal spray coating, spray forming, or additive manufacturing.

The core and skin layers of the present invention are conventionally melted and cast to form ingots, and the melting and casting process is not particularly limited, and may be any means and methods known to those skilled in the art for melting and casting, and may be adjusted according to the actual process.

In the invention, the billets are made into plates, and the thickness ratio of each layer of the plates is controlled by controlling the thickness ratio of each plate before compounding; the ingot may be extruded or processed in any other suitable manner to obtain a sheet, and if the sheet thickness does not match the target ratio, the slab or plate may be hot rolled and/or cold rolled to adjust to the desired thickness without particular limitation to the particular process.

The thickness of the hot rolled sheet is preferably 3 to 8mm, and may be 3.0mm、3.3mm、3.6mm、3.8mm、4.1mm、4.4mm、4.6mm、4.9mm、5.2mm、5.4mm、5.7mm、5.9mm、6.2mm、6.5mm、6.7mm、7mm、7.3mm、7.5mm、7.8mm or 8mm, for example, but not limited to the values listed, and other values not listed in the range are equally applicable.

The thickness of the cold rolled sheet is preferably 0.05 to 5.0mm, and may be 0.05mm、0.32mm、0.58mm、0.84mm、1.1mm、1.36mm、1.62mm、1.88mm、2.14mm、2.4mm、2.66mm、2.92mm、3.18mm、3.44mm、3.7mm、3.96mm、4.22mm、4.48mm、4.74mm or 5.0mm, for example, but not limited to the values listed, and other values not listed in the range are equally applicable.

The annealing process in the above process is not particularly limited, and any means and manner known to those skilled in the art for annealing may be used, and may be adjusted according to the actual process. It is worth to be noted that, the present invention can obtain different finished product states by adjusting and controlling the annealing process, and the description is omitted here.

Preferably, the compounding includes compounding the core ingot saw cut face thickness with the skin layer and the middle layer.

In a third aspect, the present invention provides the use of an aluminium alloy brazing composite according to the first aspect in a heat exchanger.

Compared with the prior art, the invention has at least the following beneficial effects:

The aluminum alloy brazing composite material provided by the invention has the advantages that the brazing flux is pre-buried in the composite layer in advance, the residual amount of the brazing flux can be reduced, and the brazing can be realized without adjusting the process and equipment; furthermore, the thickness of each layer of the aluminum alloy brazing composite material is compositely adjusted, so that the mechanical strength and related performance of the final aluminum alloy brazing composite material can be ensured.

Drawings

Fig. 1 is a schematic structural view of an aluminum alloy brazing composite material provided in embodiment 1 of the present invention.

Fig. 2 is a schematic structural view of an aluminum alloy brazing composite material provided in example 2 of the present invention.

Fig. 3 is a schematic structural view of an aluminum alloy brazing composite material provided in embodiment 3 of the present invention.

Fig. 4 is a schematic structural view of an aluminum alloy brazing composite material provided in example 4 of the present invention.

Fig. 5 is a schematic structural view of an aluminum alloy brazing composite material provided in example 5 of the present invention.

Fig. 6 is a schematic structural view of an aluminum alloy brazing composite material provided in example 6 of the present invention.

Fig. 7 is a schematic structural view of an aluminum alloy brazing composite material according to example 7 of the present invention.

Fig. 8 is a schematic structural view of an aluminum alloy brazing composite material provided in example 8 of the present invention.

Fig. 9 is a schematic structural view of an aluminum alloy brazing composite material provided in example 9 of the present invention.

Fig. 10 is a schematic structural view of an aluminum alloy brazing composite material according to example 10 of the present invention.

Fig. 11 is a schematic structural view of an aluminum alloy brazing composite material provided in example 11 of the present invention.

In the figure, 1-core layer; 2-embedding a brazing flux composite layer; 21-surface layer; 22-an intermediate layer; 3-a water-contacting layer; 4-barrier layer.

The drawings of the present invention show only the lamination relationship of the layers, and the thickness relationship of the layers shown in the drawings is not equivalent to the actual composition ratio relationship, which is disclosed in the examples.

Detailed Description

To facilitate understanding of the present invention, examples are set forth below. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.

All technical terms used herein are defined to be in conflict with the meanings commonly understood by one of ordinary skill in the art to which this invention pertains.

When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or an upper preferable range value, and a lower preferable range value, this is to be understood as equivalent to any range specifically disclosed by combining any pair of upper range values or preferred range values with any lower range value or preferred range value, regardless of whether the range is specifically disclosed. Unless otherwise indicated, the numerical ranges set forth herein are intended to include the endpoints of the ranges, and all integers and fractions within the range. For example, "1-8" encompasses 1, 2,3, 4, 5, 6, 7, 8 and any range consisting of any two values therein, e.g., 2-6, 3-5.

All percentages, parts, ratios, etc. are by weight unless otherwise specified.

The terms "about," "approximately," when used in conjunction with a numerical variable, generally refer to the numerical value of the variable and all values of the variable within experimental error (e.g., within a confidence interval of 95% for an average) or within ±2%, ±5% of the specified value, or a wider range.

The expression "comprising" or similar expressions "including", "containing" and "having" etc. synonymously therewith are open ended and do not exclude additional unrecited elements, steps or components. The expression "consisting of …" excludes any element, step or component not specified. The expression "consisting essentially of …" means that the scope is limited to the specified elements, steps, or components, plus any elements, steps, or components that are optionally present that do not materially affect the basic and novel characteristics of the claimed subject matter. It should be understood that the expression "comprising" encompasses the expressions "consisting essentially of …" and "consisting of …".

Except in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, or parameters of defined ingredients herein are to be understood as being defined in all instances by the term "about".

The term "optional" or "optionally" as used herein means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

All alloying element components in the invention are in weight percent; when the concentration of the alloying element component is less than 0.01%, it is considered to be free, marked-, and the element content remains in two decimal places.

By way of further example, term definitions are included herein to better understand the teachings of the present invention.

First, the composition and thickness of each layer in the aluminum alloy brazing composite material are described:

Core layer

The element composition comprises less than or equal to 1 percent of Si and less than or equal to 0.7 percent of Fe according to mass percent, cu is less than or equal to 1 percent, mn is more than or equal to 0.9 and less than 1.82 percent, mg is less than or equal to 0.3 percent.

The core alloy may also be other series alloys, such as 6000 series alloys, in the presence of a barrier layer.

The reason and range of addition of each alloy element in the core layer of the present invention will be described in detail below.

Si can improve the casting performance of the material and also contributes to improving the post-welding performance of the material, but too high Si can reduce the melting point of the material and reduce the anti-corrosion performance of the material.

Fe can play a role in refining grains, but too high Fe can easily form coarse compounds, and reduce material performance and corrosion resistance.

Cu can increase the strength and corrosion potential of the material, but Cu too high can reduce the processability and melting point of the material.

Mn is a main element in 3000-series alloy, mainly plays a role of solid solution strengthening, and too low results in insufficient material strength, and too high results in formation of coarse compounds.

Mg and flux react to render the flux ineffective and are not typically added to atmosphere-protected braze composites.

The grain structure of the core layer may be fibrous or recrystallized depending on the final working state of the material, and its average grain size after brazing is 20 to 2000 μm.

Surface layer

The surface layer is made of aluminum-silicon alloy, and the liquidus temperature of the aluminum-silicon alloy is not more than 620 ℃; the invention is not particularly limited in the range of the alloy element component of the surface layer, and any aluminum-silicon alloy with liquidus temperature not exceeding 620 ℃ can be used as the surface layer of the invention. Exemplary are: and 6-13% of Si. The aluminum-silicon alloy is exemplified by: si is 6-13% by mass, most typically AA4045, AA4343 or A4047.

In an exemplary embodiment, the alloy composition of the surface layer aluminum-silicon alloy includes: si7.65%, fe0.17%, other single elements less than or equal to 0.05%, and the liquidus temperature of the aluminum-silicon alloy is 615 ℃.

In an exemplary embodiment, the alloy composition of the surface layer aluminum-silicon alloy includes: si7.70%, fe0.19%, zn1.0%, other single elements less than or equal to 0.05%, and the liquidus temperature of the aluminum-silicon alloy is 609 ℃.

In an exemplary embodiment, the alloy composition of the surface layer aluminum-silicon alloy includes: si7.72%, fe0.18%, zn3.0% and other single elements less than or equal to 0.05%, and the liquidus temperature of the aluminum-silicon alloy is 606 ℃.

In an exemplary embodiment, the alloy composition of the surface layer aluminum-silicon alloy includes: si9.75%, fe0.15%, other single elements less than or equal to 0.05%, and the liquidus temperature of the aluminum-silicon alloy is 599 ℃.

In an exemplary embodiment, the alloy composition of the surface layer aluminum-silicon alloy includes: si9.78%, fe0.16%, zn1.0%, other single elements less than or equal to 0.05%, and the liquidus temperature of the aluminum-silicon alloy is 596 ℃.

In an exemplary embodiment, the alloy composition of the surface layer aluminum-silicon alloy includes: 12% of Si, 0.18% of Fe, less than or equal to 0.05% of other single elements and the liquidus temperature of the aluminum-silicon alloy is 580 ℃.

If the liquidus line is too high, a higher brazing temperature is required, and if the brazing temperature is high, the material corrosion is reduced, or the core material is over-burned.

Intermediate layer

The reason and range of addition of each alloy element in the core layer 2 of the present invention will be described in detail below.

The middle layer 4 is an aluminum-silicon alloy pre-embedded with brazing flux, and the liquidus temperature of the aluminum-silicon alloy is not more than 620 ℃; the present invention is not particularly limited in the range of the alloying element components of the intermediate layer 4, and any aluminum-silicon alloy having a liquidus temperature of not more than 620 ℃ is applicable as the intermediate layer 4 of the present invention. Exemplary are: and 6-13% of Si. The aluminum-silicon alloy is exemplified by: si is 6-13% by mass, most typically AA4045 and AA4343 and AA4047.

In an exemplary embodiment, the alloy composition of the surface layer 3 aluminum silicon alloy includes: si7.57%, fe0.15, other single items less than or equal to 0.05%, and the liquidus temperature of the aluminum-silicon alloy is 616 ℃.

In an exemplary embodiment, the alloy composition of the surface layer 3 aluminum silicon alloy includes: si7.66%, fe 0.14%, zn1.1%, other single items less than or equal to 0.05%, and the liquidus temperature of the aluminum-silicon alloy is 608 ℃.

In an exemplary embodiment, the alloy composition of the surface layer 3 aluminum silicon alloy includes: si7.65%, fe 0.16%, zn2.9% and other single items less than or equal to 0.05%, and the liquidus temperature of the aluminum-silicon alloy is 606 ℃.

In an exemplary embodiment, the alloy composition of the surface layer 3 aluminum silicon alloy includes: si9.80%, fe0.17, other single items less than or equal to 0.05%, and the liquidus temperature of the aluminum-silicon alloy is 598 ℃.

In an exemplary embodiment, the alloy composition of the surface layer 3 aluminum silicon alloy includes: si9.69%, fe 0.17%, zn0.8%, other single items less than or equal to 0.05%, and the liquidus temperature of the aluminum-silicon alloy is 597 ℃.

In an exemplary embodiment, the alloy composition of the surface layer 3 aluminum silicon alloy includes: 12.1% of Si, 0.2% of Fe, less than or equal to 0.05% of other single items, and the liquidus temperature of the aluminum-silicon alloy is 580 ℃.

In the aluminum-silicon alloy pre-embedded with the brazing flux, the mass percentage of the brazing flux is 1% -20%; the mass percentage of the brazing flux determines the welding quality, the difficulty of mixing the brazing flux with the aluminum silicon powder and the brazing flux residue, the brazing flux residue after brazing is increased too much, the difficulty of mixing the aluminum silicon powder is increased, and the brazing quality is reduced too little. The higher the brazing flux percentage content is, the lower the composite ratio of the aluminum-silicon alloy pre-embedded with the brazing flux is, so that the brazing flux content is generally ensured, the waste is avoided, and the brazing quality of a client can be met.

In a typical embodiment, the mass percentage of the brazing flux is 1%;

in a typical embodiment, the mass percentage of the brazing flux is 4%;

in a typical embodiment, the mass percentage of the brazing flux is 5%;

In a typical embodiment, the mass percentage of the brazing flux is 8%;

In a typical embodiment, the mass percentage of the brazing flux is 12%;

in a typical embodiment, the mass percentage of the brazing flux is 15%;

size D90 of flux 70um or less, and D50 20um or less.

Structure of pre-buried brazing flux composite layer

The pre-buried brazing flux composite layer is not limited to only contain a middle layer and a surface layer arranged on the middle layer, and can be expanded to a multi-layer structure. For example, a barrier layer (for blocking Mg element diffusion into the intermediate layer) and/or a water-contact layer (for use as a corrosion sacrificial material, improving the corrosion resistance of the composite material) may be included, wherein the single layer barrier layer has a thickness ratio of 5% to 15%, for example, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 11%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5% or 15%, etc.; the thickness ratio of the single-layer water-contact layer is 5% to 15%, and may be, for example, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 11%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, or the like. It is also possible to have an intermediate layer and a surface layer on one side and only a barrier layer and/or a water-contact layer on the other side, as determined by the process requirements and the subsequent corrosion resistance requirements.

The following detailed examples are given, wherein the numbers given in the following tables represent the percentages by mass.

The composition of the different core layers is shown in table 1.

TABLE 1

The composition of the different skin layers is shown in table 2.

TABLE 2

The composition of the different interlayers is shown in Table 3, D90 and D50 units in Table 3 are μm and indicate the particle size of the flux.

TABLE 3 Table 3

Intermediate layer	Si	Fe	Cu	Mn	Mg	Cr	Zn	Ti	Zr	Liquidus (DEG C)	The content of the brazing flux is%	D90	D50
														Z1	7.57	0.15	-	-	-	-	-	-	-	616	15	65	18
Z2	7.66	0.14	-	-	-	-	1.1	-	-	605	1.5	70	19.8
														Z3	7.65	0.16	-	-	-	-	2.9	-	-	597	2.5	68	18.6
Z4	9.8	0.17	-	-	-	-	-	-	-	598	3.8	57	16.5
														Z5	9.69	0.17	-	-	-	-	0.8			596	1	62	15.7
Z6	12.1	0.2	-	-	-	-	-	-	-	580	18.5	55	15.3
														Z7	6	0.45	-	-	-	-	0.88	-	-	617	20	60	13.4
Z8	7.2	0.65	-	-	-	-	-	-	-	618	16	42	14.6
														Z9	8.5	0.55	-	-	-	-	0.23	-	-	610	17	48	16.7
Z10	13	0.25	-	-	-	-	-	-	-	585	10.2	53	16.2
														Z11	9.78	0.16	-	-	-	-	-	-	-	596	5％	35	12.4
Z12	9.83	0.18	-	-	-	-	-	-	-	595	15％	36	13
														Z13	9.67	0.18	-	-	-	-	-	-	-	596	12％	32	11.9
Z14	9.66	0.17	-	-	-	-	-	-	-	598	5％	35	12.3
														Z15	9.72	0.21	-	-	-	-	-	-	-	598	5％	40	12.6
Z16	9.71	0.22	-	-	-	-	-	-	-	597	5％	37	12
														Z17	9.73	0.2	-	-	-	-	-	-	-	597	15％	29	12.4
Z18	9.71	0.17	-	-	-	-	-	-	-	597	15％	33	12.3
														Z19	9.69	0.18	-	-	-	-	-	-	-	596	15％	35	12.4
DZ1	5	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	623	Same as 1	Same as 1	Same as 1
														DZ2	14	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	600	Same as 1	Same as 1	Same as 1
DZ3	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	2 Is identical to	3 Is identical to	0.5	Same as 1	Same as 1
														DZ4	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	Same as 1	22	Same as 1	Same as 1

The composition of the barrier layer is shown in table 4.

TABLE 4 Table 4

Barrier layer	Si	Fe	Cu	Mn	Mg	Cr	Zn	Ti	Zr
										F1	0.2	0.19	-	0.06	-	-	1.01	-	-
F2	0.45	0.15	0.01	0.51	-	-	-	0.01	-
										F3	0.07	0.3	0.02	0.01	-	-	-	0.018	-

The composition of the water-contact layer is shown in Table 5.

TABLE 5

Water-contact layer	Si	Fe	Cu	Mn	Mg	Cr	Zn	Ti	Zr
										C1	0.81	0.24	0.17	1.66	-	-	2.51	0.01	0.08
C2	0.33	0.29	-	0.15	-	-	1.05	-	-
										C3	0.8	0.24	0.03	1.62	-	-	1.59	0.02	0.11

The following detailed description of the embodiments is made with different composite structures, where Rp _0.2 and R _m are in units of Mpa; the numbers in the corresponding columns of the composite ratios are spaced apart by "/", the numbers represent the corresponding thickness ratios of the components of the front column, and the composite ratio 15/5/60/5/15 in 1-1 of example 1 represents the thicknesses of the layers B4, Z10, X15, Z8 and B11 in the component columns of 15%, 5%, 60%, 5% and 15% of the total thickness, respectively, and the others are similar and will not be described again.

Example 1

The composite structure provided in this embodiment is shown in fig. 1, and the composite structure includes: skin 21-intermediate layer 22-core 1-intermediate layer 22-skin 21, specific compositions and compounding ratios and test properties are shown in table 6.

TABLE 6

Example 2

The composite structure provided in this embodiment is shown in fig. 2, and the composite structure includes: the specific composition and the composite ratio of the surface layer 21, the intermediate layer 22 and the core layer 1 are shown in Table 7.

TABLE 7

Example 3

The composite structure provided in this embodiment is shown in fig. 3, and the composite structure includes: the specific compositions and the compounding ratios of the surface layer 21, the intermediate layer 22, the core layer 1 and the water-contacting layer 3 are shown in Table 8.

TABLE 8

Example 4

The composite structure provided in this embodiment is shown in fig. 11, and the composite structure includes: the specific compositions and the compounding ratios and test properties of the skin layer 21-intermediate layer 22-barrier layer 4-core layer 1-barrier layer 4 are shown in Table 9.

TABLE 9

Example 5

The composite structure provided in this embodiment is shown in fig. 5, and the composite structure includes: skin layer 21-intermediate layer 22-barrier layer 4-core layer 1-barrier layer 4-intermediate layer 22-skin layer 21, the specific compositions and the compounding ratios and test properties are shown in table 10.

Table 10

Example 6

The composite structure provided in this embodiment is shown in fig. 6, and the composite structure includes: skin layer 21-intermediate layer 22-water-contact layer 3-core layer 1-intermediate layer 22-skin layer 21, specific compositions and compounding ratios and test performances are shown in table 11.

TABLE 11

Example 7

The composite structure provided in this embodiment is shown in fig. 7, and the composite structure includes: skin layer 21-intermediate layer 22-water-contact layer 3-core layer 1-water-contact layer 3-intermediate layer 22-skin layer 21, specific compositions and composite ratios and test performances are shown in table 12.

Table 12

Example 8

The composite structure provided in this embodiment is shown in fig. 8, and the composite structure includes: the specific composition and the compounding ratio and the test properties of the surface layer 21-intermediate layer 22-water-contact layer 3-core layer 1-water-contact layer 3 are shown in Table 13.

TABLE 13

Example 9

The composite structure provided in this embodiment is shown in fig. 9, and the composite structure includes: the specific compositions and compounding ratios and test properties of skin layer 21-intermediate layer 22-barrier layer 4-core layer 1 are shown in Table 14.

TABLE 14

Example 10

The composite structure provided in this embodiment is shown in fig. 10, and the composite structure includes: the specific composition and the compounding ratio and the test properties of the surface layer 21-intermediate layer 22-barrier layer 4-core layer 1-water-contacting layer 3 are shown in Table 15.

TABLE 15

Example 11

The composite structure provided in this embodiment is shown in fig. 11, and the composite structure includes: skin layer 21-intermediate layer 22-water-contact layer 3-core layer 1-barrier layer 4-intermediate layer 22-skin layer 21, specific compositions and composite ratios and test properties are shown in table 16.

Table 16

The preparation method of the aluminum alloy brazing composite material provided by the embodiment and the comparative example comprises the following steps:

The core layer and the surface layer are respectively and independently smelted and cast into a billet in sequence, wherein the smelting temperature is 735 ℃ of the core layer, 785 ℃ of the surface layer, and the casting method and the casting steps comprise feeding, alloying, slag skimming, refining, standing and casting in sequence;

and (3) hot rolling the surface layer billet at 500 ℃, and rolling the surface layer billet to a target thickness according to the design requirement of the recombination rate.

The intermediate layer is made into billets by hot isostatic pressing of aluminum containing brazing flux particles or aluminum alloy containing brazing flux particles, the pressure of the hot isostatic pressing is 100Pa, and the temperature is 420 ℃. And then the intermediate layer billet is formed into a billet plate through extrusion and friction stir welding.

Carrying out hot rolling on the billets according to the target thickness at 500 ℃ to prepare a plate, and compounding to form a composite plate;

the composite plate is subjected to hot rolling at 500 ℃, cold rolling at normal temperature and annealing in sequence to obtain the aluminum alloy brazing composite material, wherein the aluminum alloy brazing composite material is a plate, namely a brazing plate.

The testing method comprises the following steps:

1. Alloy element composition: the GB/T7999-2015 is implemented by a direct-reading spectrometer or by EDS, EDX, GDOES equipment.

2. The thickness ratio is as follows: the average value is calculated by randomly marking the thickness value of each layer at 5 positions by adopting metallography or surface scanning, a microscope or SEM or EPMA.

3. Total thickness of material: the thickness values at 5 positions were randomly marked using a micrometer, and the average value was calculated.

4. Solidus or liquidus: DSC equipment, which performs the standard GB/T1425-2021.

5. Corrosion potential: electrochemical workstation, performing standard astm g69-2020.

6. And (3) braze welding evaluation: the resulting aluminum alloy brazing composite sheet was processed to 60mm by 60mm and was formed into a T-shaped test piece with a 60mm by 60mm AA3003 sheet having a thickness of 1 mm. The aluminum alloy brazing composite plate is horizontally placed, the AA3003 plate is vertically placed on the plane of the aluminum alloy brazing composite plate, brazing filler metal AA4045 with the width of 1mm multiplied by 1mm is arranged on one side of the contact position of the two plates, and the brazing filler metal AA4045 is placed in a quartz tube furnace for simulated brazing, and nitrogen protection is adopted in the quartz tube furnace. Simulating a brazing process: raising the temperature to 605 ℃ at a heating rate of 30 ℃/min, preserving the temperature for 3min, taking out the sample, and air-cooling to room temperature; and evaluating the joint condition of the two plates, observing the condition of a welded joint by using a metallographic microscope, and judging that the brazing is successful if the joint is full, and judging that the brazing is failed if the joint is corroded or the joint is in cold joint.

7. Post-weld performance: according to GB/T228.1-2010 section 1 of tensile test of metallic Material: the method disclosed in room temperature test method is used for testing mechanical properties after brazing, wherein an aluminum alloy composite tube material to be tested is processed into a dumbbell-shaped sample according to A50 tensile sample standard, then the dumbbell-shaped sample is subjected to simulated brazing, the brazing process is that the temperature is raised to 603 ℃ from room temperature and the temperature is kept for 3min, then the sample is taken out from a simulated brazing furnace (muffle furnace), and the sample is naturally cooled to room temperature; the test index was a predetermined plastic elongation Rp0.2 (unit is MPa) and tensile strength Rm (unit is MPa).

The present invention is described in detail by the above embodiments, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must be implemented depending on the above detailed features. It should be apparent to those skilled in the art that any modifications, equivalent substitutions for selected features of the present invention, addition of auxiliary features, selection of specific modes, etc. fall within the scope of the invention and the disclosure.

Claims

1. An aluminum alloy brazing composite material is characterized by comprising a pre-buried brazing flux composite layer and a core layer;

the intermediate layer comprises aluminum-silicon alloy pre-embedded with brazing flux, and the liquidus temperature of the aluminum-silicon alloy in the intermediate layer is not more than 620 ℃.

2. The aluminum alloy brazing composite material according to claim 1, wherein the mass percentage of the brazing flux in the intermediate layer is 1-20%;

preferably, the size D90 of the flux in the intermediate layer is less than or equal to 70 μm and D50 is less than or equal to 20 μm.

3. The aluminum alloy brazing composite according to claim 1 or 2, wherein the core layer is an aluminum manganese alloy;

preferably, the core layer comprises, in mass percent: si is less than or equal to 1%, fe is less than or equal to 0.7%, cu is less than or equal to 1.0%, mn is less than or equal to 0.9% and less than or equal to 1.82%, mg is less than or equal to 0.3%, and the solidus temperature of the aluminum-manganese alloy is not lower than 605 ℃;

Preferably, the average grain size of the core layer after brazing is 20 to 2000 μm.

4. An aluminium alloy brazing composite according to any one of claims 1 to 3, wherein the surface layer is an aluminium-silicon alloy, the liquidus temperature of the aluminium-silicon alloy in the surface layer being no more than 620 ℃;

preferably, the intermediate layer and the surface layer each independently comprise Si in mass percent: 6 to 13 percent.

5. The aluminum alloy brazing composite according to any one of claims 1 to 4, wherein the pre-buried flux composite layer is provided on both sides or on a single side of the core layer;

preferably, the ratio of the thickness of the single layer of the pre-buried brazing flux composite layer to the thickness of the aluminum alloy brazing composite material is 1-30%;

Preferably, the total thickness of the pre-buried brazing flux composite layer accounts for less than or equal to 40% of the thickness of the aluminum alloy brazing composite material.

6. The aluminum alloy brazing composite according to any one of claims 1 to 5, wherein the thickness of the intermediate layer on one side is 0.5 to 5% of the thickness of the aluminum alloy brazing composite;

Preferably, the thickness of the surface layer is greater than or equal to the thickness of the intermediate layer;

preferably, the thickness of the aluminum alloy brazing composite material is 0.05-5.0 mm.

7. The aluminum alloy brazing composite according to any one of claims 1 to 6, wherein the aluminum alloy brazing composite has a yield strength after brazing of not less than 40MPa and a tensile strength of not less than 120MPa;

8. A method of preparing an aluminum alloy brazing composite material according to any one of claims 1 to 7, comprising the steps of:

Preparing the billets into plates according to the thickness, and compounding to form a composite plate;

9. The method according to claim 8, wherein the thickness of the hot rolled sheet is 3 to 8mm;

Preferably, the thickness of the cold-rolled sheet is 0.05-5.0 mm.

10. Use of the aluminium alloy brazing composite according to any one of claims 1 to 7 in a heat exchanger.