A self-brazing aluminum alloy material, its manufacturing method and applications

Abstract

This application relates to a self-brazing aluminum alloy material comprising: Al, Si, Cu, Zn, Mg, Sr, and one or more of the following elements optionally present: Fe, Mn, Ti, Zr, and Cr; wherein, when present, the content of each element, based on the weight of the self-brazing aluminum alloy material, satisfies the following relationships: the total content of Si and Fe is 1.5-6.5 wt%, and the ratio of Si to Fe is 5 or more; the total content of Mn and Cu is 1.5-5.5 wt%, and the ratio of Cu to Mn is 0.5 or more; the total content of Zn and Mg is 0.5-5.5 wt%, the content of Mg is 0.05-0.6 wt%, and the ratio of Zn to Mg is 5 or more; the total content of Ti, Zr, and Cr is less than 0.5 wt%; and the Sr content is 0.003-0.2 wt%. The self-brazing aluminum alloy material of this application can form a brazed joint with good brazing quality with the parts to be brazed through partial melting during the brazing process. Moreover, the preparation process is simple and low-cost, easy to use, and has good application prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aluminum alloy materials, in particular to a self-brazing aluminum alloy material, a manufacturing method and use thereof, and a brazing method using the self-brazing aluminum alloy material. BACKGROUND

[0002] Brazing is an efficient metal joining technique, which is a method of using a metal material with a lower melting point than the base material as a filler metal, heating the base material to a certain temperature (a temperature higher than the melting point of the filler metal and lower than the melting point of the base material), and melting the filler metal to wet and fill the gap between the solid-state base material, thereby forming a firm joint. During brazing, the deformation is small, the joint is smooth and beautiful, and it is suitable for welding precise, complex and component composed of different materials, such as aluminum heat exchangers, honeycomb structure plates, etc. Before brazing, the workpiece generally needs to be carefully processed and cleaned to remove oil stains and thick oxide films, and the interface assembly gap is ensured, and the use of brazing flux can increase the wettability of the filler metal. The gap is generally required to be between 0.02-0.15 millimeters. Compared with fusion welding, the base material is not melted during brazing, only the filler metal is melted; compared with pressure welding, no pressure is applied to the welded parts during brazing. The weld formed by brazing is called a brazing seam. The filler metal used for brazing is called a filler metal. The main heating methods for brazing include flame heating, furnace heating, resistance heating, induction heating, etc.

[0003] The brazing temperature of aluminum alloy is usually around 600℃, at which time the filler metal alloy (usually Al-Si alloy) is completely melted, and the liquid filler metal flows to the joint through capillary action to form a metallurgical joint. The aluminum alloy brazing material is usually a composite material comprising a core layer and at least one filler metal layer, and the alloy of the filler metal layer is generally a low-melting-point alloy relative to the core layer, usually an Al-Si alloy. The filler metal layer will melt preferentially under high-temperature brazing conditions, and then flow to the joint to be welded through capillary action, thereby achieving metal connection between various parts. In order to remove the oxide film on the surface of aluminum, flux is generally applied before brazing. However, the multi-layer composite material has a long processing flow, high processing cost, complex production process, long time consumption and low production efficiency.

[0004] In addition to using a composite material with a filler metal layer for brazing, Al-Si filler metal powder or filler metal sheet can also be used for brazing. However, the added filler metal powder is a powder particle, which has more oxide film on the surface, and more flux needs to be used, and spraying powder between the parts to be welded can easily lead to uneven surface spraying, resulting in unstable quality of the brazed joint, and easy occurrence of defects such as slag inclusion and porosity. When using filler metal sheet, if the fit is not tight or the solder sheet has surface contamination such as oil stains, it will also lead to unstable quality of the brazed joint.

[0005] There is currently some research on aluminum alloy materials with self-brazing properties, which form brazing joints by partial melting of the aluminum alloy material itself during brazing. CN115106677A discloses a single-layer self-brazing aluminum alloy material and a preparation method thereof. The aluminum alloy contains a certain amount of Si, Zr, and Zr elements, and has good self-brazing performance. SUMMARY

[0006] In the current prior art, the self-brazing properties of aluminum alloy materials are mainly achieved by controlling the Si content range, and other elements such as Mn, Fe, Cu, Zn, etc. are added to adjust the strength or other properties of the material. The applicant found that for aluminum alloy materials, in addition to the Si element, other elements also have the effect of reducing the melting point of the aluminum alloy to form partial melting of the aluminum alloy material during brazing, but there is no related research in the prior art.

[0007] In one aspect, the present application relates to a self-brazing aluminum alloy material comprising: Al, Si, Cu, Zn, Mg, Sr, and optionally one or more of the following elements: Fe, Mn, Ti, Zr, and Cr; wherein, when present, the content of each element satisfies the following relationships based on the weight of the self-brazing aluminum alloy material: the total content of Si and Fe is 1.5-6.5wt%, and the ratio of the content of Si to Fe is 5 or more; the total content of Mn and Cu is 1.5-5.5wt%, and the ratio of the content of Cu to Mn is 0.5 or more; the total content of Zn and Mg is 0.5-5.5wt%, the content of Mg is 0.05-0.6wt%, and the ratio of the content of Zn to Mg is 5 or more; the total content of Ti, Zr, and Cr is 0.5wt% or less; and the content of Sr is 0.003-0.2wt%.

[0008] In one embodiment, the ratio of the distribution of particles with an equivalent circle diameter of 0.1-2.0pm to the distribution of particles with an equivalent circle diameter greater than 2.0pm in the material is 2 or more, preferably 2.5 or more.

[0009] In one embodiment, the distribution of particles with an equivalent circle diameter of 0.1-2.0pm in the material is 5000 / mm 2 The above.

[0010] In one embodiment, the thickness of the material is 0.2mm or more, preferably 0.25mm or more, more preferably 0.5mm or more.

[0011] In one embodiment, at 600°C, the volume of melted material in the material is 10-35% of the overall volume of the material, preferably 15-30%, more preferably 20-30%.

[0012] In another aspect, the present application relates to a method for manufacturing the self-brazing aluminum alloy material of the present application, comprising the following steps: casting a self-brazing aluminum alloy material ingot according to the elemental composition; after milling and heating, hot rolling the self-brazing aluminum alloy material ingot to a certain thickness; after cooling, cold rolling to a target thickness; softening annealing.

[0013] In one embodiment, the casting of the self-brazing aluminum alloy material ingot adopts a semi-continuous casting process, wherein the cooling speed during the casting process is above 100℃ / min.

[0014] In yet another aspect, the present application relates to the use of the self-brazing aluminum alloy material of the present application in large-area brazing.

[0015] In yet another aspect, the present application relates to a brazing method, comprising the following steps: applying a brazing flux on the self-brazing aluminum alloy material of the present application and / or the brazing surface of the component to be brazed; assembling the self-brazing aluminum alloy material and the component to be brazed so that the brazing surfaces contact each other; heating to melt part of the material of the self-brazing aluminum alloy material, and the melted material wets and fills the gap between the brazing surfaces; and cooling to form a brazed joint.

[0016] In one embodiment, the material of the component to be brazed is aluminum, and the heating temperature is 600-650℃, and the heating time is 20-90min.

[0017] In one embodiment, the material of the component to be brazed is steel, and the heating temperature is 650-700℃, and the heating time is 20-90min. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 : Configuration comprising the self-brazing aluminum alloy material of the present application;

[0019] Figure 2 : Microstructure photograph of the self-brazing aluminum alloy material of the present application;

[0020] Figure 3 : (a) Low-magnification photograph and (b) high-magnification photograph of the brazed joint of a self-brazing aluminum sheet and a stainless steel sheet according to one embodiment of the present application;

[0021] Figure 4 : (a) Low-magnification photograph and (b) high-magnification photograph of the brazed joint of a self-brazing aluminum sheet and an aluminum sheet according to one embodiment of the present application. DETAILED DESCRIPTION

[0022] General definitions and terms

[0023] All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety, if not otherwise indicated.

[0024] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art to which this application belongs. If there is a conflict between the definitions provided in this document and those provided in the art to which this application belongs, the definitions provided in this document control.

[0025] Unless otherwise indicated, all percentages, parts, ratios, etc., are by weight.

[0026] When a range, a preferred range, or a preferred limit is given, unless otherwise stated, it is intended that every narrower range, or preferred limit falling within the broader range is also contemplated. For example, if a range of 1-8 is stated, it is intended that the range 2-6, or 3-5, or 4-4.5, or 4.5-4.5, or 4.5-4.5-4.5, etc. are also contemplated. When a range of values is recited, unless otherwise stated, the range is intended to include the endpoints, and all integers and fractions within that range. The scope of the application is not limited to the specific values recited when the range is defined. For example, "1-8" encompasses 1, 2, 3, 4, 5, 6, 7, 8, and any sub-range formed by any two of those values, e.g., 2-6, 3-5.

[0027] The terms "about," "approximately," when used in connection with a numerical value, generally mean the numerical value and all numerical values within experimental error (e.g., within 95% confidence interval for a mean value) or within ±10% of the stated numerical value, or within a broader range.

[0028] The terms "comprising," "including," "containing," "have" or "involving," and other similar forms, as used in the specification, are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. It will be appreciated by persons of the art that the terms described above, such as "comprising," encompass the terms "consisting of." The term "consisting of" excludes any element, step, or ingredient not specified. The term "consisting essentially of" means a range limited to the specified elements, steps, or ingredients, plus optional elements, steps, or ingredients that do not materially affect the basic and novel characteristics of the claimed subject matter. It will be understood that the term "comprising" encompasses the terms "consisting essentially of" and "consisting of."

[0029] The term "selected from the group consisting of" means one or more elements from the group listed thereafter, independently selected, and can include combinations of two or more elements.

[0030] When numerical values or ranges are described herein, it is to be understood that the disclosure is intended to encompass the particular value or end point recited, as well as any value or end point within the range.

[0031] The terms "one or more" or "at least one" as used herein, means one, two, three, four, five, six, seven, eight, nine, or more.

[0032] Further, where the number of a component or element of the present application is not specified, there is no limit to the number of occurrences (or presence) of the component or element. Thus, one or at least one is to be interpreted to include one or at least one, and the singular word form of the component or element also includes the plural unless the number clearly indicates a single instance.

[0033] The term "optional" or "optionally" as used herein means that the subsequently described event or circumstance can or can not occur, and thus such description includes instances where the event or circumstance occurs and instances where it does not.

[0034] The term "unavoidable impurity element" as used herein means an element which is not intentionally added but unavoidably enters the alloy during the production of the aluminum alloy. The "other elements" means elements which are not included in the elements already specified in the corresponding alloy.

[0035] Self-brazing aluminium alloy material

[0036] In one aspect, the present application relates to a self-brazing aluminum alloy material, which has a suitable relationship between its constituent elements and their contents, so that the aluminum alloy material has self-brazing performance and good mechanical properties.

[0037] As described above, the conventional brazing process is usually carried out with the simultaneous participation of flux and filler metal. A metal material with a lower melting point than the base material is used as the filler metal, and the base material is heated to a certain temperature (a temperature higher than the melting point of the filler metal and lower than the melting point of the base material), so that the filler metal melts while the base material does not. The molten filler metal wets and fills the gap between the solid base material, forming a strong brazed joint.

[0038] In this context, the "self-brazing aluminum alloy material" specifically refers to an aluminum alloy material that has the following characteristics: in the brazing process, no filler metal is needed, and the self-brazing aluminum alloy material (as the base material) can itself have part of its internal material melt under heating conditions. This molten part can wet and fill the gap at the brazing position, forming a brazed joint.

[0039] In actual use, the self-brazing aluminum alloy material, in addition to the self-brazing property, also needs to have suitable mechanical properties (such as tensile strength, etc.) to meet the needs of the use scenario.

[0040] The present inventors have found that when Si, Cu, Mg, Zn, etc. are added to aluminum materials, they can effectively reduce the melting temperature of the aluminum material, which helps to achieve the self-brazing performance of the material.

[0041] Si element has an important influence on the performance of aluminum alloy material. Si element can effectively reduce the melting point of the material. When Si element is added alone in the aluminum material, 1wt% of Si solid solution can reduce the melting point of the material by about 50°C. In addition, Si can also form AlFeMnSi compounds with Fe and Mn to play a role of dispersion strengthening. Si can also form Mg2Si compounds by reacting with Mg, thereby improving the strength of the material. In addition, Si can be solid-solved in the material matrix to improve the strength of the material by solid solution strengthening. Therefore, Si element is an element that must be added to ensure the self-brazing performance and mechanical properties of the self-brazing aluminum alloy material of the present application. A suitable Si content in the aluminum alloy material is beneficial to provide a suitable melting point reduction effect and maintain the mechanical properties such as strength of the material. In an embodiment, the content of Si can be 1.25-6.5wt%, for example, about 1.80wt%, about 2.93wt%, about 4.22wt% and the like, based on the weight of the self-brazing aluminum alloy material. If the content of Si is too high, the melting volume of the material may be too much at the same brazing temperature, which can cause the thickness of the material to be severely thinned, which is not conducive to the size retention thereof; if the content of Si is too low, the melting volume may be too small at the same brazing temperature, which can cause the brazing joint to be too small and the strength of the brazing joint to be reduced.

[0042] Cu can reduce the melting point of the material. When Cu element is added alone in the aluminum material, 1wt% of Cu solid solution can reduce the melting point of the material by about 20°C. Cu can also improve the strength of the core material layer by solid solution strengthening and can improve the potential. The content of Cu can be 0.5-5.5wt%, for example, about 2.51wt%, about 1.39wt%, about 0.92wt% and the like, based on the total weight of the self-brazing aluminum alloy material. If the content of Cu is too low, the advantageous effect brought by it is not obvious; if the content of Cu is too high, the possibility of intergranular corrosion increases, and it can significantly affect the melting point.

[0043] Zn element can also reduce the melting point of the aluminum material. When Zn element is added alone in the aluminum material, 1wt% of Zn solid solution can reduce the melting point of the material by about 4°C. Zn element can also improve the corrosion resistance by improving the sacrificial anode effect. The content of Zn can be 0.017-5.5wt%, for example, about 0.65wt%, about 2.82wt%, about 1.58wt% and the like, based on the weight of the self-brazing aluminum alloy material. Too low or too high content of Zn is not conducive to achieving its advantageous effect.

[0044] Mg element can reduce the melting point of the material. When Mg element is added alone in the aluminum material, 1 wt% of Mg solid solution can reduce the melting point by about 14°C. Mg can also significantly improve the strength of the alloy, and the effect of improving the strength is achieved by solid solution strengthening or by precipitating Mg2Si. The content of Mg can be 0-0.92wt% based on the weight of the self-brazing aluminum alloy material, for example, about 0.60wt%, about 0.33wt%, about 0.24wt% and the like. When the content of Mg is too high, Mg may volatilize and diffuse during brazing, which has an adverse effect on the activity of the flux, thereby resulting in poor brazing effect; excessive Mg is also prone to grain boundary corrosion.

[0045] The addition of Sr element helps to refine the as-cast structure formed during casting, especially the Al-Si as-cast structure. The content of Sr can be 0.003-0.2wt% based on the weight of the self-brazing aluminum alloy material, preferably 0.005-0.15wt%, for example, about 0.005wt%, 0.015wt%, 0.07wt%, 0.08wt%, 0.10wt%, 0.15wt% and the like. When the content of Sr is too high, coarse compounds such as Al4Sr are easily formed during casting, which affects the performance of the material; when the content of Sr is too low, the effect of refining the as-cast structure almost disappears, resulting in coarse as-cast structure.

[0046] Fe element can combine with other elements such as Mn and Si to form casting crystalline phases, which can become intermetallic compounds with the size of recrystallization nuclei, thereby reducing the recrystallization temperature. The content of Fe can be 0-1.10wt% based on the weight of the self-brazing aluminum alloy material, for example, about 0.32wt%, about 0.55wt%, about 0.71wt% and the like, thereby ensuring good formability and corrosion resistance of the material. Too high content of Fe can reduce the corrosion resistance of the composite material and also reduce the strength of the material.

[0047] Mn element in the material helps to adjust and improve the strength, brazing property, corrosion resistance and potential of the material. In an embodiment, the content of Mn can be 0-1.5wt% based on the weight of the self-brazing aluminum alloy material, for example, about 0.60wt%, about 0.89wt%, about 1.35wt% and the like. When the content of Mn is too low, the advantageous effect is not obvious; when the content of Mn is too high, coarse Mn-containing particles are formed, which affects the rolling production and causes holes or broken strips in the material.

[0048] Ti improves the strength by solid solution strengthening and improves the corrosion resistance. The content of Ti is 0.25 wt% or less, preferably 0.15 wt% or less, for example, about 0.08 wt%, 0.11 wt%, 0.09 wt%, etc., based on the weight of the self-brazing aluminum alloy material. If the content of Ti is too high, it is easy to form a large amount of intermetallic compounds, which reduces the plastic workability.

[0049] Zr is added as an alloying element to further improve the strength of the alloy after brazing and to control the size of the recrystallized grains. The content of Zr can be 0.25 wt% or less, for example, about 0.04 wt%, about 0.05 wt%, etc., based on the weight of the self-brazing aluminum alloy material.

[0050] Cr is added as an alloying element to further improve the strength of the alloy after brazing and to improve the corrosion resistance. The content of Cr can be 0.4 wt% or less, for example, about 0.03 wt%, about 0.10 wt%, about 0.19 wt%, etc., based on the weight of the self-brazing aluminum alloy material.

[0051] Controlling the melting range of the aluminum alloy material is an important factor in imparting the self-brazing property to the material. The applicant has also found that when a combination of multiple elements is added to the aluminum material, the influence of these elements on the melting point of the material is complicated due to the mutual influence between the various elements, which in turn affects the self-brazing property.

[0052] In the present application, the self-brazing aluminum alloy material has a suitable content relationship between the constituent elements, which imparts the self-brazing property to the material and enables good brazing results, and also has good mechanical properties. The self-brazing aluminum alloy material of the present application comprises: Al, Si, Cu, Zn, Mg, Sr, and optionally one or more of the following elements: Fe, Mn, Ti, Zr, and Cr; wherein, when present, the content of each element based on the weight of the self-brazing aluminum alloy material satisfies the following relationships: the total content of Si and Fe is 1.5-6.5 wt%, and the ratio of the content of Si to Fe is 5 or more, for example, 5.6, 5.3, 5.9, etc.; the total content of Mn and Cu is 1.5-5.5 wt%, and the ratio of the content of Cu to Mn is 0.5 or more, for example, 0.7, 1.6, 2.1, 4.2, 10.9, etc.; the total content of Zn and Mg is 0.5-5.5 wt%, the content of Mg is 0.05-0.6 wt%, and the ratio of the content of Zn to Mg is 5 or more, for example, 5.4, 6.0, 8.5, 6.6, 5.2, etc.; the total content of Ti, Zr, and Cr is 0.5 wt% or less; and the content of Sr is 0.005-0.15 wt%. The self-brazing aluminum alloy material satisfying the above relationships between the constituent elements can have a self-brazing function and good brazing quality, and ensure its mechanical properties.

[0053] It is to be understood that in addition to the above-mentioned elements, some unavoidable impurities will be introduced into the material during production, preparation, etc. In the present application, the content of the unavoidable impurities in the autogenous brazing aluminium alloy material is low, typically below 0.15 wt.%. A low content of impurities can reduce the possible influence on the properties of the material as much as possible.

[0054] The present applicant has found that the microstructure of the material also influences the autogenous brazing properties. In particular, the distribution of particles of a certain size in the material influences the autogenous brazing properties of the material.

[0055] The ratio of smaller particles to larger particles in the autogenous brazing aluminium alloy material influences the brazing properties. In one embodiment, the ratio of the distribution of particles having an equivalent circle diameter of 0.1 to 2.0 μm to the distribution of particles having an equivalent circle diameter of more than 2.0 μm in the autogenous brazing aluminium alloy material is more than 2, preferably more than 2.5, for example about 2.6, 3.1, 3.2, 3.3, 3.4, 3.5, etc. A too low ratio can result in a decrease of the brazing properties.

[0056] A certain amount of smaller particles in the autogenous brazing aluminium alloy material can further improve the autogenous brazing properties of the material. In one embodiment, the distribution of particles having an equivalent circle diameter of 0.1 to 2.0 μm in the autogenous brazing aluminium alloy material is more than 5000 particles per mm 2 , or more than 6000 particles per mm 2 , or more than 7000 particles per mm 2 , or more than 7500 particles per mm 2 , for example, the distribution of particles having an equivalent circle diameter of 0.1 to 2.0 μm in the autogenous brazing aluminium alloy material is about 11225 particles per mm 2 , 7539 particles per mm 2 , 18766 particles per mm 2 , 24537 particles per mm 2 , 16698 particles per mm 2 A too low distribution of particles having an equivalent circle diameter of 0.1 to 2.0 μm in the autogenous brazing aluminium alloy material can also have a negative influence on the brazing properties.

[0057] The term "equivalent circle diameter" as used herein can also be referred to as "equivalent diameter" and means the diameter of a circular particle having an area equal to the area of the irregularly shaped particle. The particle density can be determined by conventional methods, for example by means of an image analysis system connected to an optical microscope. Figure 2 A photograph of the autogenous brazing aluminium alloy material of the present application obtained by means of an optical microscope is shown, wherein particles dispersed in the autogenous brazing aluminium alloy material are shown, for example as shown in the circular frame.

[0058] For the purpose of explanation only and not limitation, the distribution of particles of a particular size in the material can affect the self-brazing performance of the material based on the following factors: the thermal conductivity of the larger size particles is worse than that of the smaller size particles, and the gap between the larger size particles is relatively larger, thus, it can cause the particles to be difficult to melt and there can be more locations that are not melted (i.e. the gap between the particles) during brazing, which can result in a decrease in the strength of the brazed joint. The presence of a large number of uniformly distributed smaller size particles in the material allows the brazing site of the self-brazing material to melt smoothly, uniformly and sufficiently during brazing, to well wet the gap between the surfaces to be brazed, and to form a strong brazed joint.

[0059] In order to achieve good brazing results in use of the self-brazing aluminum alloy material, it is necessary to control the proportion of the melted part of the material at the brazing temperature. If the proportion of the melted part of the self-brazing material is too small at the brazing temperature, the melted material cannot sufficiently wet and fill the gap at the brazing site, and brazing cannot be completed or the brazing result is poor. If the proportion of the melted part of the self-brazing material is too high at the brazing temperature, the shape of the material can change significantly during brazing, which is not conducive to the shape retention of the material. In the present application, by the above-mentioned composition and structural design, the volume of the melted material in the material at 600°C is 10-35% of the total volume of the material, preferably 15-30%, more preferably 20-30%, for example about 23.7%, 25.3%, 28.1%, 26.9%, 25.3%, etc. Such a design ensures that at the usual aluminum alloy brazing temperature (about 600-700°C), the appropriate volume of the melted material can be obtained to achieve good brazing results.

[0060] The thickness of the self-brazing aluminum alloy material usually affects the brazing results. When brazing at the same temperature, the heat transfer rate of the material is higher when the thickness of the material is thinner, and the heat transfer rate of the material is lower when the thickness of the material is thicker. The difference in heat transfer rate affects the brazing results of self-brazing aluminum alloy materials of different thicknesses.

[0061] In particular, when the thickness of the self-brazing aluminum alloy material is high (such as aluminum alloy plates, pipes, etc.), the heat transfer rate is slow under brazing conditions, and at the same brazing furnace gas temperature, the actual metal temperature is too low, resulting in a small brazed joint and low joint strength. In addition, due to the large thickness of the material, it is not conducive to the filling of the gap at the brazing site by the melted material. Therefore, it is challenging to achieve the self-brazing function of the material with a large thickness.

[0062] The self-brazing material of the present application has suitable composition and microstructure, which enables the self-brazing material of the present application to maintain excellent self-brazing performance even under the condition of relatively thick thickness, and the self-brazing performance is excellent. This significantly widens the applicable scenarios of the self-brazing aluminum alloy material of the present application. In an embodiment, the thickness of the self-brazing aluminum alloy material can be 0.2 mm or more, or 0.25 mm or more, or 0.3 mm or more, or 0.5 mm or more, or 1.0 mm or more, etc. The thickness of the self-brazing aluminum alloy material may, for example, be about 1.45 mm, about 1.65 mm, about 2.45 mm, about 1.20 mm, about 1.35 mm, etc.

[0063] Method for manufacturing a self-brazing aluminium alloy material

[0064] In another aspect, the present application also relates to a method for manufacturing a self-brazing aluminum alloy material, which comprises the following steps: casting a self-brazing aluminum alloy material ingot according to the elemental composition; after milling the surface of the self-brazing aluminum alloy material ingot and heating, hot rolling to a certain thickness; after cooling, cold rolling to a target thickness; softening annealing.

[0065] According to the elemental composition of the self-brazing aluminum alloy material, the self-brazing aluminum alloy material ingot, for example, a slab, can be cast by using a semi-continuous casting process. In this process, the cooling rate during casting is controlled to be above a certain rate, which helps to refine the grains and as-cast eutectic structure, and reduces the number of intermetallic compounds formed during casting. In an embodiment, the cooling rate during casting is 100°C / min or more. Too low cooling rate will significantly increase the number of intermetallic compounds formed during casting.

[0066] The self-brazing aluminum alloy material ingot is milled to obtain a flat surface, and the milling depth can be 5-15 mm. After the milling is completed, the ingot is heated, which can be carried out by using conventional equipment, for example, a heating furnace. The heating temperature and time can be selected according to the actual situation. The heating temperature can be 400-510°C, and the heating time can be 5-20 hours.

[0067] The heated ingot is hot rolled to a certain thickness. It can be rolled to a certain thickness by multiple passes. In an embodiment, the heated ingot is hot rolled from the initial thickness to 2-7 mm by 10-20 passes. The hot rolling final rolling temperature can be controlled to be below 320°C. After hot rolling, the material can be coiled to form a hot rolled coil.

[0068] The hot rolled material is cooled, and then rolled to a target thickness by a cold rolling mill.

[0069] The material of the target thickness obtained is subjected to soft annealing. The soft annealing can reduce the residual rolling oil, eliminate internal stress and reduce the strength, preventing cracking in the subsequent processing. The temperature of the soft annealing can be reasonably selected according to the specific composition of the self-brazing aluminum alloy material, but should be lower than the temperature at which the material in the self-brazing aluminum alloy material can melt, so as to avoid melting of the self-brazing aluminum alloy material in the soft annealing process. The temperature of the soft annealing can be 300-380°C. The time of the soft annealing can be 5-15 hours.

[0070] The self-brazing aluminum alloy material can have various forms according to actual needs, including but not limited to: sheet, coil, etc.

[0071] In addition to being prepared into a single-layer material, the self-brazing aluminum alloy material of the present application can also be prepared into a two-layer or three-layer material, for example Figure 1 The self-brazing aluminum alloy material of the present application can be prepared into a two-layer or three-layer material as a composite layer or core material according to needs. When prepared into a two-layer or three-layer material, the alloy of the core material or composite layer matched therewith can be selected from 1xxx, 3xxx, 6xxx aluminum alloy, etc., and the melting point of the aluminum alloy is above 620°C.

[0072] Figure 1 a shows a single-layer core material 1 formed by the self-brazing aluminum alloy material of the present application. Figure 1 b shows a two-layer material formed by the core material 1 and a composite layer 2, wherein the material of the composite layer 2 is the self-brazing aluminum alloy material of the present application. The material of the core material 1 can be selected from 1xxx, 3xxx, 6xxx aluminum alloy, etc., and the melting point of the aluminum alloy is above 620°C. Figure 1 c shows a two-layer material formed by the core material 1 and a composite layer 2, wherein the material of the core material 2 is the self-brazing aluminum alloy material of the present application, and the material of the composite layer 2 can be selected from 1xxx, 3xxx, 6xxx aluminum alloy, etc., and the melting point of the aluminum alloy is above 620°C. Figure 1 d shows a three-layer material formed by the core material 1, a composite layer 2 and a composite layer 2'. The materials of the composite layer 2 and the composite layer 2' can be the self-brazing aluminum alloy material of the present application. The materials of the composite layer 2 and the composite layer 2' can be the same or different. The material of the core material 1 can be selected from 1xxx, 3xxx, 6xxx aluminum alloy, etc., and the melting point of the aluminum alloy is above 620°C.

[0073] Use of a self-brazing aluminium alloy material

[0074] In another aspect, the present application also relates to the use of the self-brazing aluminum alloy material of the present application in brazing, in particular in large-area connection.

[0075] In the prior art, good brazing effect can be obtained by preparing a composite material with a brazing filler layer, but the preparation cost is high, especially for large-area connection brazing, the cost will increase significantly. In the prior art, brazing is also performed using an additional Al-Si brazing filler powder or brazing filler sheet. Since the brazing filler powder is a powder particle, a large amount of flux needs to be used to remove the oxide film on the surface, and spraying the powder between the parts to be welded can easily lead to uneven surface spraying, resulting in unstable quality of the brazed joint, and defects such as slag inclusion and porosity are prone to occur. When using a brazing filler sheet, if the fit is not tight or the brazing sheet has surface contamination such as oil stains, it will also lead to unstable quality of the brazed joint, and is also not suitable for large-area connection brazing.

[0076] The self-brazing aluminum alloy material of the present application does not need to use additional brazing filler during brazing, has good brazing effect, and low preparation cost. For large-area connection brazing, it can also achieve good brazing effect and low cost. The material of the present application is suitable for various brazing environments, such as controlled atmosphere brazing, vacuum brazing, induction brazing, etc. Thus, the material of the present application can have wide application in various scenarios.

[0077] Brazing method

[0078] In yet another aspect, the present application also relates to a brazing method, comprising the following steps: applying flux on the surface to be brazed of the self-brazing aluminum alloy material and / or the part to be welded; assembling the self-brazing aluminum alloy material and the part to be welded so that the surfaces to be brazed are in contact; heating to melt part of the material of the self-brazing aluminum alloy material, and the melted material wets and fills the gap between the surfaces to be brazed; cooling to form a brazed joint.

[0079] The flux can be made of a substance that destroys the oxides on the surfaces to be brazed during brazing. The flux can be an inorganic salt, preferably containing F, and can also contain at least one of the following elements: Al, K, Li, Na, Cs. Examples of inorganic salts include but are not limited to: potassium fluoroaluminate (such as KAlF4, K2AlF5·H2O, K3AlF6, etc.), hydroxyfluoroaluminate, sodium fluoroaluminate, cesium aluminum fluoride, potassium fluorosilicate, etc. Other possible inorganic salts include: AlF3, NaF, KF, LiF, K 1-3 AlF 4-6 , Cs 1-3 AlF 4-6 , Li3AlF6and Cs x Al y F2. The above salts can be used alone or in the form of a mixture. Hydrates of the above salts can also be used.

[0080] The brazing flux can be applied to the surface of the self-brazing aluminum alloy material to be brazed, to the surface of the part to be welded to be brazed, or to the surfaces of both the self-brazing aluminum alloy material and the part to be welded to be brazed. The amount of the brazing flux applied should be sufficient to destroy the oxide film on the surface to be brazed, thereby facilitating good brazing. In one embodiment, the amount of the brazing flux applied is 5-15 g / m2. 2 .

[0081] After the brazing flux is applied, the self-brazing aluminum alloy material and the part to be welded are assembled so that the surfaces to be brazed are in contact. The surfaces to be brazed that are in contact form the location to be brazed. Before heating, the assembled self-brazing aluminum alloy material and the part to be welded can be dried to remove moisture, which helps to avoid the reaction of residual moisture with the brazing flux at high temperatures, thereby affecting the removal of the oxide film by the brazing flux.

[0082] During heating, the brazing flux at the location to be brazed destroys the oxide film on the surface, and part of the self-brazing aluminum alloy material melts and wets and fills the gap at the location to be brazed.

[0083] The heating process can be carried out in a continuous welding furnace. The self-brazing aluminum alloy material of the present application can form good brazed joints with parts made of various materials. For the self-brazing aluminum alloy material of the present application, the welding process needs to be adjusted according to the material of the part to be welded to achieve the best welding effect.

[0084] In one embodiment, the material of the part to be welded is aluminum, the temperature of the heating process for melting part of the self-brazing aluminum alloy material is 600-650°C, and the heating time is 20-90 min. When the material of the part to be welded is aluminum, the welding process can be carried out under the protection of nitrogen.

[0085] In one embodiment, the material of the part to be welded is steel (e.g., stainless steel), the temperature of the heating process for melting part of the self-brazing aluminum alloy material is 650-700°C, and the heating time is 20-90 min. When the material of the part to be welded is steel, the welding process can be carried out under the protection of ammonia decomposition gas (decomposed into nitrogen and hydrogen).

[0086] Advantages

[0087] The self-brazing aluminum alloy material of the present application can be used in a wide thickness range and has a wide application range, and is suitable for use as various plate materials or pipe materials, etc. By controlling the proportioning of various elements and the particle distribution, the self-brazing aluminum alloy material of the present application can well meet the application requirements in practice, especially the requirements for self-brazing materials with high thickness. The self-brazing material of the present application has a simple production process, a short production flow and a high yield, and is a self-brazing aluminum alloy material with high performance and capable of significantly reducing the production cost and material cost. The self-brazing aluminum alloy material of the present application can obtain excellent brazing quality without using brazing filler metal, and has low manufacturing cost, which is beneficial to large-scale use.

[0088] Examples

[0089] The technical scheme of the present application will be further described in detail below in combination with specific examples.

[0090] It should be noted that the following examples are only examples for clearly illustrating the technical scheme of the present application, and are not a limitation on the present application. Those skilled in the art can make other different forms of changes or variations on the basis of the above description, and all the changes or variations are not enumerated here, and the changes or variations thus extended are still within the protection scope of the present application. Unless otherwise specified, the instruments and reagent materials used in the present application are commercially available.

[0091] The samples of Examples 1-5 were prepared by the following steps:

[0092] Table 1 shows the alloy composition of the examples of the present application, and Table 2 shows the relevant parameter characteristics of Examples 1-5.

[0093] After the alloy composition shown in Table 1 was prepared, a semi-continuous casting process was used to obtain a slab, and the cooling speed was 100-200℃ / min;

[0094] After the slab was milled (milling depth 10mm) and loaded into a heating furnace, the heating temperature was 470-490℃, and the heating time was 5-20 hours;

[0095] After the slab was taken out of the heating furnace, it was hot-rolled, and after 10-20 passes, it was hot-rolled to a thickness of 2-7mm, and then coiled into a hot-rolled coil, and the final hot-rolling temperature was controlled below 320℃;

[0096] After the hot-rolled coil was cooled, it was rolled to the target thickness (as shown in Table 3) by a cold rolling mill, and then annealed, and the annealing temperature was 320-360℃, and the total annealing time was 10-15 hours, and the plate-shaped self-brazing aluminum alloy material of Examples 1-5 was prepared.

[0097] Table 1

[0098]

[0099] Table 2

[0100]

[0101] The samples of Examples 1-5 and other conventional materials (see Table 3) were used as test materials, and were tested and evaluated according to the following method, and the results are shown in Table 3.

[0102] Gas shielded brazing of different components

[0103] Aluminium-aluminium brazing The test material and the component to be welded were coated with a brazing flux on the surface, and the amount of the brazing flux added was 5-10 g / m2. 2 The test material and the component to be welded were then assembled and dried, and then were loaded into a continuous brazing furnace, the furnace temperature was set to 600-650°C, and the brazing process was protected by nitrogen gas throughout the process, and the time from loading into the furnace to unloading was controlled to be 20-90 min.

[0104] Aluminium-steel brazing The test material and the component to be welded were coated with a brazing flux on the surface, and the amount of the brazing flux added was 10-15 g / m2. 2 The test material and the component to be welded were then assembled and dried, and then were loaded into a continuous brazing furnace, the furnace temperature was set to 650-700°C, and the brazing process was protected by ammonia decomposition gas (nitrogen + hydrogen) throughout the process, and the time from loading into the furnace to unloading was controlled to be 20-90 min.

[0105] The above brazed components were sampled, and after the metallographic sample preparation process of inlaying, rough grinding, and fine polishing, the brazed joints were evaluated by optical microscopy, and the evaluation results are shown in Table 3.

[0106] Table 3

[0107]

[0108] The brazing effects of the brazing of the components to be welded of different materials by the samples of Examples 1-5 of the present application in Test Nos. 1-8 are shown. From the evaluation results, it can be seen that the self-brazing aluminum alloy material of the present application can realize brazing between the components to be welded of aluminum and stainless steel, and form good brazed joints, and obtain good brazing effects.

[0109] The brazed joints of Test Nos. 1 and 2 are shown in Figs. Figure 3 and Figure 4 From the figures, it can be seen that the brazed joints of the sample of Example 1 with aluminum and stainless steel are good, and there is no virtual welding phenomenon.

[0110] In test numbers 9-10, the test material is a composite material of AA3003 (core material) and AA4045 (solder layer) with a composite ratio of 10%, and a good quality solder joint can also be obtained, but compared with the material of the present application, the preparation cost of this composite material is higher, which is not conducive to large-scale use.

[0111] In test numbers 11-12, the test material is AA3003 (core material) with a thickness of 1.5 mm, and AA4045 solder sheet with a thickness of 0.15 mm is matched thereon. From the evaluation results of the solder joint, the soldering quality is poor. Compared with test numbers 1-8, there are more pores in the solder joint of test numbers 11-12, and the soldering quality is lower.

[0112] In summary, the self-soldering aluminum alloy material of the present application can form a good solder joint with the parts to be welded by partial melting during the soldering process, can replace the composite material with a solder layer and the aluminum material using solder sheet, has the characteristics of short process, convenient use, low cost and good soldering effect, and is suitable for use as aluminum-aluminum, aluminum-steel and other soldering applications that require large-area connection.

[0113] The above has disclosed the technical content and technical features of the present disclosure. However, it can be understood that under the creative idea of the present disclosure, those skilled in the art can make various changes and improvements to the disclosed concepts, but they belong to the protection scope of the present disclosure. The description of the above embodiments is illustrative rather than limiting, and the protection scope of the present disclosure is determined by the claims.

Claims

1. A self-brazing aluminum alloy material comprising: Al, Si, Cu, Zn, Mg, Sr, Fe, Mn, and optionally one or more of the following elements: Ti, Zr, and Cr; wherein, the content of each element, when present, satisfies the following relationships based on the weight of the self-brazing aluminum alloy material: the total content of Si and Fe is 1.5 to 6.5 wt%, the content of Si is 1.25 to 4.22 wt%, and the ratio of the content of Si to Fe is 5 or more; the total content of Mn and Cu is 1.5 to 5.5 wt%, and the ratio of the content of Cu to Mn is 0.5 or more; the total content of Zn and Mg is 0.5 to 5.5 wt%, the content of Mg is 0.05 to 0.6 wt%, and the ratio of the content of Zn to Mg is 5 or more; the content of Sr is 0.003 to 0.2 wt%; and the total content of Ti and Zr and Cr is 0.5 wt% or less.

2. The self-brazing aluminum alloy material of claim 1, wherein, in the material, the ratio of the distribution of particles having an equivalent circle diameter of 0.1 to 2.0 μm to the distribution of particles having an equivalent circle diameter of more than 2.0 μm is 2 or more.

3. The self-brazing aluminum alloy material of claim 1, wherein, in the material, the ratio of the distribution of particles having an equivalent circle diameter of 0.1 to 2.0 μm to the distribution of particles having an equivalent circle diameter of more than 2.0 μm is 2.5 or more.

4. The self-brazing aluminum alloy material of claim 1, wherein, The material has a particle distribution of equivalent circle diameters of 0.1 to 2.0 μm at 5000 / mm 2 The above.

5. The self-brazing aluminum alloy material of claim 1, wherein, the thickness of the material is 0.2 mm or more.

6. The self-brazing aluminum alloy material of claim 1, wherein, the thickness of the material is 0.25 mm or more.

7. The self-brazing aluminum alloy material of claim 1, wherein, the thickness of the material is 0.5 mm or more.

8. The self-brazing aluminum alloy material of any one of claims 1 to 7, wherein, at 600°C, the volume of the material that is melted is 10 to 35% of the total volume of the material.

9. The self-brazing aluminum alloy material of claim 8, wherein, at 600°C, the volume of the material that is melted is 15 to 30% of the total volume of the material.

10. The self-brazing aluminum alloy material of claim 8, wherein, at 600°C, the volume of the material that is melted is 20 to 30% of the total volume of the material.

11. A method of manufacturing the self-brazing aluminum alloy material of any one of claims 1 to 10, comprising the steps of: casting an ingot of the self-brazing aluminum alloy material according to the elemental composition; after milling and heating the ingot of the self-brazing aluminum alloy material, hot-rolling to a certain thickness; after cooling, cold-rolling to a target thickness; soft annealing.

12. The method of claim 11, wherein, the ingot of the self-brazing aluminum alloy material is cast using a semi-continuous casting process, wherein, the cooling rate during casting is 100°C / min or more.

13. Use of the self-brazing aluminum alloy material of any one of claims 1 to 10 for brazing in large area joining.

14. A brazing method comprising the steps of: coating a flux on the self-brazing aluminum alloy material and / or the brazing surface of the part to be brazed in any one of claims 1-10; assembling the self-brazing aluminum alloy material and the part to be brazed so that the brazing surfaces contact each other; heating so that part of the material of the self-brazing aluminum alloy material melts, and the melted material wets and fills the gap between the brazing surfaces; cooling to form a brazing joint.

15. The method of claim 14, wherein, the material of the part to be brazed is aluminum, and the heating temperature is 600-650℃, and the heating time is 20-90min; or the material of the part to be brazed is steel, and the heating temperature is 650-700℃, and the heating time is 20-90min.

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