Double-flux-cored welding ring and preparation method thereof

Abstract

The invention relates to a double-flux-cored welding ring which comprises a seamless flux-cored wire with a cesium fluoroaluminate brazing flux as a flux core and a seamed flux-cored wire with a potassium fluoroaluminate brazing flux as a flux core, and the seamless flux-cored wire is clamped between two layers of brazing filler metal which are overlapped by the seamed flux-cored wire to form a closed opening. The seamless flux-cored wire adopts brazing filler metal with the melting point lower than that of the seamed flux-cored wire, and the mass ratio of the cesium fluoroaluminate brazing flux to the potassium fluoroaluminate brazing flux ranges from 1: 3 to 1: 10. And high-performance brazing of the magnesium-containing aluminum alloy can be achieved through cesium fluoroaluminate with the low content, so that the cost is reduced, and the method is suitable for high-quality brazing of magnesium-containing aluminum alloy pipe fittings.

Description

Technical Field

[0001] This invention belongs to the field of brazing, and relates to a brazing material, specifically a double flux-cored welding ring and its preparation method. Background Technology

[0002] With the development of new energy vehicles and the requirements for lightweight vehicles, the demand for magnesium-aluminum alloys in automotive piping and other components is increasing. Adding magnesium to aluminum alloys can significantly improve their strength. In Al-Mg alloys, for every 1 wt.% increase in magnesium, the tensile strength (Rm) increases by approximately 34 MPa. Simultaneously, magnesium can also work synergistically with other elements in the alloy, such as silicon, zinc, and manganese, to enhance the alloy's performance. Magnesium-aluminum alloys possess good processing properties and strength, meeting the processing and usage requirements of automotive piping; their low density makes them an ideal choice for lightweight design, significantly reducing the weight of automotive piping systems and contributing to improved fuel economy or the driving range of electric vehicles. Commonly used magnesium-aluminum alloys in automotive piping include 5-series aluminum-magnesium alloys (Mg: 1%~5%) and 6-series aluminum-magnesium-silicon alloys (Mg: 0.35%~1.2%), with common examples including 5083, 5052, 5005, 6061, 6063, 6082, and 6005.

[0003] One of the commonly used methods for welding aluminum alloys is brazing. Aluminum is chemically reactive and has a strong affinity for oxygen, readily forming a dense oxide film on its surface. This hinders atomic diffusion between the base metal and the filler metal, significantly reducing wettability. Therefore, flux is required for brazing aluminum alloys. Aluminum-silicon brazing filler metals are the most widely used type of aluminum filler metal in automotive piping brazing due to their excellent wettability, fluidity, corrosion resistance, and machinability. Potassium fluoroaluminate is the standard flux for aluminum-silicon brazing filler metals. Flux can be added using flux-cored rings in the brazing of pipe fittings.

[0004] Flux-cored welding rings are typically made from flux-cored welding wire. Flux-cored welding wire with aluminum alloy brazing filler metal coated with flux can improve welding quality, simplify operating procedures, increase production efficiency, and enable large-scale automated production. Currently, flux-cored welding wires are mainly divided into welded flux-cored wires and seamless flux-cored wires.

[0005] In the process of brazing magnesium-aluminum alloys using potassium fluoroaluminate as flux, potassium fluoroaluminate reacts chemically with magnesium to form KMgF3. This compound has a melting point between 750 and 800°C, far exceeding the brazing temperature of most aluminum alloys. Unmelted KMgF3 hinders the wetting of the filler metal in the base material, affecting the final brazing result. In contrast, cesium fluoroaluminate reacts with magnesium to form CsMgF3, which has a lower melting temperature (630°C) and does not impede brazing. Therefore, cesium fluoroaluminate flux is primarily used for brazing magnesium-aluminum alloys.

[0006] With the development of cutting-edge technologies such as quantum computing, space exploration, and new medical devices, the demand for cesium is increasing. Meanwhile, the global reserves of major cesium mines are decreasing due to continuous mining, and the discovery and commissioning of new deposits are time-consuming and difficult. These factors have led to a sustained rise in cesium prices. Cesium fluoroaluminate, used as a flux, has also become expensive due to the high price of cesium. Therefore, reducing the cesium content in flux-cored solders while ensuring soldering performance has become particularly important.

[0007] In conclusion, there is an urgent need to develop flux-cored welding rings with low cesium content that can ensure the brazing quality of magnesium-aluminum alloy pipe fittings. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a double flux-cored welding ring that enables high-performance brazing of magnesium-aluminum alloys using a lower content of cesium fluoroaluminate, thereby reducing costs and making it suitable for high-quality brazing of magnesium-aluminum alloy pipe fittings.

[0009] On one hand, the present invention provides a dual flux-cored welding ring, comprising a seamless flux-cored welding wire with cesium fluoroaluminate flux as the flux core and a slotted flux-cored welding wire with potassium fluoroaluminate flux as the flux core. The seamless flux-cored welding wire is sandwiched between two layers of brazing filler metal formed by stacking the slotted flux-cored welding wire to form a joint. The seamless flux-cored welding wire uses brazing filler metal with a lower melting point than the slotted flux-cored welding wire. The mass ratio of cesium fluoroaluminate flux to potassium fluoroaluminate flux is in the range of 1:3 to 1:10.

[0010] In a preferred embodiment, the potassium fluoroaluminate flux is selected from potassium fluoroaluminate flux and potassium fluoroaluminate flux with added other components.

[0011] In a preferred embodiment, the potassium fluoroaluminate flux is selected from potassium fluoroaluminate flux containing zinc halide, alkali metal halide, alkaline earth metal halide, alkali metal salt of fluoroaluminate, alkaline earth metal salt of fluoroaluminate, alkali metal salt of zinc fluoroaluminate, alkaline earth metal salt of zinc fluoroaluminate, alkali metal salt of fluorosilicate, and alkaline earth metal salt of fluorosilicate.

[0012] In a preferred embodiment, the cesium fluoroaluminate flux is selected from cesium fluoroaluminate flux and cesium fluoroaluminate flux with added other components.

[0013] In a preferred embodiment, the cesium fluoroaluminate flux is selected from potassium fluoroaluminate flux containing zinc halide, alkali metal halide, alkaline earth metal halide, alkali metal salt of fluoroaluminate, alkaline earth metal salt of fluoroaluminate, alkali metal salt of zinc fluoroaluminate, alkaline earth metal salt of zinc fluoroaluminate, alkali metal salt of zinc fluoroaluminate, and alkaline earth metal salt of fluorosilicate.

[0014] In a preferred embodiment, the flux content in the dual flux-cored solder ring is in the range of 5 wt% to 35 wt%.

[0015] In a preferred embodiment, the solder of the slotted flux-cored wire of the dual flux-cored welding ring is an aluminum-silicon solder.

[0016] In a preferred embodiment, the solder of the seamless flux-cored wire of the dual flux-cored welding ring is a zinc-aluminum solder or a silicon-aluminum solder.

[0017] In a preferred embodiment, the aluminum-silicon based solder is selected from Al-Si alloy solder, Al-Si-Ag alloy solder, Al-Si-Cu alloy solder, Al-Si-Mg alloy solder, Al-Si-Zn alloy solder, Al-Si-Ti alloy solder, Al-Si-Sr alloy solder, Al-Si-Ge alloy solder, Al-Si-Ce alloy solder, Al-Si-Cu-Zn alloy solder, Al-Si-Cu-Ni alloy solder, Al-Si-Cu-RE alloy solder, Al-Si-Ti-Sr alloy solder, Al-Si-Ti-Ce alloy solder, Al-Si-Sr-Ce alloy solder, Al-Si-Cu-Ni-RE alloy solder, Al-Si-Cu-Ni-Sr alloy solder, and Al-Si-Ti-Sr-Ce alloy solder.

[0018] On the other hand, the present invention provides a method for preparing a double flux-cored bonding ring, comprising the following steps: 1) Preparation of seamless flux-cored welding wire with cesium fluoroaluminate flux as the core; 2) Roll the brazing alloy strip into a U-shaped groove, add flux powder, and press seamless flux wire between the two layers of brazing alloy that form the joint on both sides of the U-shaped groove during the process of stacking and joining. Then, draw the wire to make a double flux wire by reducing the diameter. 3) Use a ring-making machine to make double flux-cored welding wire into double flux-cored welding rings.

[0019] In this invention, a dual-cored welding ring uses a seamless flux-cored wire with a low-melting-point cesium fluoroaluminate flux as the core and a low-melting-point brazing filler metal. During the brazing of magnesium-aluminum alloys, magnesium in the alloy is enriched and oxidized on the base material surface to form a magnesium oxide film. During heating, the seamless flux-cored wire with the lower melting point melts preferentially and flows out from the gap of the slotted flux-cored wire. The cesium fluoroaluminate flux preferentially reacts with magnesium to form CsMgF3, preventing the subsequent reaction of molten potassium fluoroaluminate with magnesium to form high-melting-point KMgF3, which would affect the wetting of the brazing filler metal in the base material. This effectively improves the oxide film removal performance of the flux and promotes the wetting and spreading of the brazing filler metal on the base material, thereby improving the brazing quality.

[0020] The seamless flux-cored wire is held between two layers of brazing filler metal formed by stacking seamed flux-cored wires. This not only facilitates the flow of the preferentially melted flux from the gap of the seamed flux-cored wire, but also prevents flux powder leakage from the seamed flux-cored wire and prevents the flux powder from absorbing moisture and affecting the welding quality.

[0021] In this invention, the mass ratio of cesium fluoroaluminate flux to potassium fluoroaluminate flux in the dual-cored welding wire is in the range of 1:3 to 1:10, which can ensure the brazing quality while significantly reducing the amount of expensive cesium fluoroaluminate.

[0022] Other beneficial effects of the present invention are reflected in the specific implementation schemes and embodiments. Attached Figure Description

[0023] Figure 1 This is a plan view of one embodiment of the dual flux-cored welding ring of the present invention; Figure 2 for Figure 1 Cross-sectional view of the middle welding ring along line AA; Figure 3 A schematic diagram of one embodiment of the welding wire used to form the double flux-cored welding ring of the present invention.

[0024] Among them: 1, welded flux-cored wire; 11, potassium fluoroaluminate flux; 12, filler metal of welded flux-cored wire; 2, seamless flux-cored wire; 21, cesium fluoroaluminate flux; 22, filler metal of seamless flux-cored wire. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments and examples. The embodiments and examples given are only for better illustrating the present invention and are not intended to limit the scope of the present invention. Therefore, the numerical values, shapes, materials, constituent elements, the arrangement and connection of constituent elements, and steps (processes) and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present invention. Thus, any constituent elements in the following embodiments that are not described in the independent claims representing the highest concept of the present invention are arbitrary constituent elements. In addition, all the drawings are schematic diagrams, in which substantially identical structures are given the same reference numerals, and repeated descriptions are omitted or simplified. Furthermore, in the following embodiments, the terms "about" or "approximately" not only mean approximately, but also include manufacturing errors or dimensional tolerances.

[0026] On one hand, the present invention provides a dual flux-cored welding ring, comprising a seamless flux-cored welding wire with cesium fluoroaluminate flux as the flux core and a slotted flux-cored welding wire with potassium fluoroaluminate flux as the flux core. The seamless flux-cored welding wire is sandwiched between two layers of brazing filler metal formed by stacking the slotted flux-cored welding wire to form a joint. The seamless flux-cored welding wire uses brazing filler metal with a lower melting point than the slotted flux-cored welding wire. The mass ratio of cesium fluoroaluminate flux to potassium fluoroaluminate flux is in the range of 1:3 to 1:10.

[0027] The brazing properties of aluminum and its alloys are inferior to those of other common metallic materials. This is mainly because a dense and chemically stable Al2O3 film readily forms on the surface of Al alloys, especially when w(Mg) > 3% in the base material. The resulting interstitial oxide film of Al2O3 + MgO is even more chemically stable and difficult to remove. Without breaking this oxide film, aluminum cannot be brazed. The purpose of using flux is to remove the oxide film on the aluminum surface, reduce the interfacial tension between the molten filler metal and the base material, and facilitate the wetting and spreading of the filler metal on the base material surface during brazing. Seamless flux-cored wire is sandwiched between two layers of filler metal formed by stacking seamed flux-cored wires. This not only facilitates the preferentially molten flux flowing out from the gaps in the seamed flux-cored wires but also prevents flux powder leakage and moisture absorption within the seamed flux-cored wires.

[0028] The flux used in the double flux-cored welding ring of this invention is a potassium fluoroaluminate-based flux. Potassium fluoroaluminate-based fluxes mainly include the commonly used Nocolok flux, which is a non-corrosive and insoluble flux. This flux is a potassium fluoroaluminate mixture composed of eutectic points in the KF-AlF3 system, with the general molecular formula K... 1~3 AlF 4~6 It may contain one molecule of water of crystallization. Other components can be added to potassium fluoroaluminate flux to lower the melting point, improve its film removal ability, etc.

[0029] In a preferred embodiment, the potassium fluoroaluminate flux in the dual flux-cored solder ring of the present invention is selected from potassium fluoroaluminate flux and potassium fluoroaluminate flux with added components, including but not limited to potassium fluoroaluminate flux with added components such as zinc halide, alkali metal halide, alkaline earth metal halide, alkali metal salt of fluoroaluminate, alkaline earth metal salt of fluoroaluminate, alkali metal salt of zinc fluoroaluminate, alkaline earth metal salt of zinc fluoroaluminate, alkali metal salt of fluorosilicate, and alkaline earth metal salt of fluorosilicate.

[0030] The flux used in the seamless flux-cored wire of the dual flux-cored ring of this invention is a cesium fluoroaluminate-based flux. Cesium fluoroaluminate-based fluxes mainly include CsF-AlF3-based fluxes. In a preferred embodiment, the cesium fluoroaluminate-based flux in the dual flux-cored ring of this invention can be selected from cesium fluoroaluminate fluxes and cesium fluoroaluminate fluxes with added components, including but not limited to cesium fluoroaluminate fluxes with added zinc halides, alkali metal halides, alkaline earth metal halides, alkali metal salts of fluoroaluminates, alkaline earth metal salts of fluoroaluminates, alkali metal salts of zinc fluoroaluminates, alkaline earth metal salts of zinc fluoroaluminates, alkali metal salts of fluorosilicates, and alkaline earth metal salts of fluorosilicates.

[0031] In this invention, the mass ratio of cesium fluoroaluminate-based flux to potassium fluoroaluminate-based flux in the dual-cored solder ring is in the range of 1:3 to 1:10, more preferably in the range of 1:4 to 1:8. Increasing the amount of cesium fluoroaluminate-based flux significantly increases costs. Conversely, insufficient cesium fluoroaluminate-based flux leads to a significant increase in processing difficulty, and the lack of sufficient flux results in insufficient cesium fluoroaluminate to react with the Mg in the base material during brazing, severely impacting brazing efficiency. Commonly used KF-CsF-AlF3 medium-temperature non-corrosive flux typically has a CsF content greater than 30 wt%. This invention significantly reduces the cesium content in the dual-cored solder ring while achieving welding quality that is even superior to that of conventional medium-temperature non-corrosive fluxes.

[0032] In a preferred embodiment, the flux content in the double flux-cored welding ring is in the range of 5 wt% to 35 wt%, preferably in the range of 5 wt% to 25 wt%. If the flux content is too low, the flux may not be able to remove the oxide film on the surface of the base material during brazing; if the flux content is too high, the proportion of flux-cored metal will be low, and the metal filler metal may not be able to fully fill the weld, affecting the strength of the welded joint.

[0033] The double flux-cored welding ring of the present invention can be selected from various brazing fillers that are suitable for aluminum-aluminum brazing or aluminum-aluminum alloy brazing with other dissimilar metals in the prior art.

[0034] In a preferred embodiment, the solder of the slotted flux-cored wire of the dual flux-cored welding ring is an aluminum-silicon solder.

[0035] In a preferred embodiment, the solder of the seamless flux-cored wire of the dual flux-cored welding ring is a zinc-aluminum solder or a silicon-aluminum solder.

[0036] Aluminum-silicon brazing filler metals refer to filler metals based on Al-Si eutectic composition, including hypoeutectic, hypereutectic, and Al-Si alloys with added elements not exceeding 5% (mass fraction). This series of filler metals exhibits excellent solderability, strength, consistency with the base material color, plating properties, and corrosion resistance, making them rare and superior filler metals. In particular, this series of filler metals can undergo modification treatment, which can greatly increase the toughness and bending performance of the filler metal and the brazed joint.

[0037] In a preferred embodiment, the solder of the seamed flux-cored wire with dual flux-cored rings can be an aluminum-silicon solder, including but not limited to aluminum-silicon solders, aluminum-silicon solders with added metallic elements that can undergo a eutectic reaction with aluminum to lower the solder's melting point, and / or aluminum-silicon solders with added modifiers or rare earth elements to improve solder performance, such as aluminum-silicon solders with added copper, magnesium, zinc, silver, nickel, germanium, bismuth, phosphorus, titanium, strontium, sodium, or rare earth elements (Er, Ce, La, Ce, Sc, etc.). Aluminum-silicon binary solders include, but are not limited to, 4343, 4043, 4045, 4047, etc.

[0038] In a preferred embodiment, the aluminum-silicon based solder is selected from Al-Si alloy solder, Al-Si-Ag alloy solder, Al-Si-Cu alloy solder, Al-Si-Mg alloy solder, Al-Si-Zn alloy solder, Al-Si-Ti alloy solder, Al-Si-Sr alloy solder, Al-Si-Ge alloy solder, Al-Si-Ce alloy solder, Al-Si-Cu-Zn alloy solder, Al-Si-Cu-Ni alloy solder, Al-Si-Cu-RE alloy solder, Al-Si-Ti-Sr alloy solder, Al-Si-Ti-Ce alloy solder, Al-Si-Sr-Ce alloy solder, Al-Si-Cu-Ni-RE alloy solder, Al-Si-Cu-Ni-Sr alloy solder, and Al-Si-Ti-Sr-Ce alloy solder.

[0039] In a preferred embodiment, the solder of the seamless flux-cored wire of the dual flux-cored welding ring is selected from zinc-aluminum solders, silicon-aluminum solders, etc., which have low melting points, including but not limited to Zn-Al-X, Al-Si-Zn, Al-Si-Cu-Zn, Al-Cu-Ag-Zn, Al-Ge-Si solders, such as Zn-Al-Ti alloy solder, Zn-Al-Cu alloy solder, Zn-Al-Cu-Si alloy solder, Zn-Al-Cu-Ni alloy solder, Zn-Al-Cu-Ni-Ag alloy solder, etc. Al-Si-Zn alloy brazing filler metal, Al-Si-Cu-Zn alloy brazing filler metal, Al-Si-Cu-Ni alloy brazing filler metal, Al-Si-Cu-Sn-Mg alloy brazing filler metal, Al-Si-Cu-Sn alloy brazing filler metal, Al-Si-Cu-Bi alloy brazing filler metal, Al-Si-Cu-Ge alloy brazing filler metal, Al-Si-Cu-Zn-Mg alloy brazing filler metal, Al-Si-Zn-Sr alloy brazing filler metal, Al-Si-Zn-Sr-Ti alloy brazing filler metal, Al-Si-Cu-Zn-RE alloy brazing filler metal. For seamless flux-cored wires with dual flux-cored bonding rings, the brazing filler metal is preferably selected from zinc-aluminum based brazing filler metals or silicon-aluminum based brazing filler metals with lower melting points, such as Al-Si-Cu-Zn alloy brazing filler metals.

[0040] On the other hand, the present invention provides a method for preparing a double flux-cored bonding ring, comprising the following steps: 1) Preparation of seamless flux-cored welding wire with cesium fluoroaluminate flux as the core; 2) Roll the brazing alloy strip into a U-shaped groove, add flux powder, and press seamless flux wire between the two layers of brazing alloy that form the joint on both sides of the U-shaped groove during the process of stacking and joining. Then, draw the wire to make a double flux wire by reducing the diameter. 3) Use a ring-making machine to make double flux-cored welding wire into double flux-cored welding rings.

[0041] Seamless flux-cored welding wires with cesium fluoroaluminate flux as the core can be prepared using various seamless flux-cored welding wire manufacturing methods known in the prior art.

[0042] This invention provides a double flux-cored welding ring suitable for aluminum-aluminum brazing of aluminum and aluminum alloy pipe fittings, as well as for brazing aluminum and aluminum alloys with other dissimilar metals, particularly for aluminum-aluminum brazing of magnesium-containing aluminum alloy pipe fittings and their brazing with other dissimilar metals. Specifically, this invention's double flux-cored welding ring is suitable for brazing 5-series aluminum-magnesium alloy and 6-series aluminum-magnesium-silicon alloy pipe fittings.

[0043] The flux content in the dual-cored welding ring of this invention is uniform and stable, without any breaks, ensuring consistent welding quality. Furthermore, it effectively improves the deoxide removal performance of the flux and promotes the wetting and spreading of the filler metal on the base material while significantly reducing the amount of expensive cesium fluoroaluminate, thereby improving brazing quality.

[0044] To test the brazing performance of the welding wire, the performance indicators and testing methods of this invention are as follows: Brazing rate: refers to the percentage of the actual welded area (after removing inclusions, porosity, and other defects) to the nominal welded area. It is measured using industrial CT scanners.

[0045] Cementation depth: refers to the depth of the filler metal flowing into the weld after brazing. Tested according to GB / T 11364-2008.

[0046] Pressure resistance: Tested according to GB / T 11618.1-2008.

[0047] Burst pressure resistance: Tested in accordance with GB / T 11618.1-2008. Example

[0048] 1. Zn98-Al2 zinc-aluminum brazing filler metal is extruded into a hollow tube with an outer diameter of 15mm and an inner diameter of 8.5mm. Cesium fluoroaluminate flux powder is then poured in, and the tube is drawn to obtain a seamless flux-cored welding wire with a diameter of Φ1.0mm.

[0049] 2. The Al88-Si12 aluminum-silicon brazing strip is rolled into a U-shaped groove, potassium fluoroaluminate flux powder is added, and seamless flux-cored wire is pressed between the two layers of brazing material forming the joint on both sides of the U-shaped groove during the stacking and joining process. Then, the wire is drawn to form a double flux-cored wire with a diameter of Φ2.0mm.

[0050] 3. Use a ring-making machine to make a double flux-cored welding wire into a double flux-cored welding ring with a diameter of Φ2.0*Φ6.9*1 turn.

[0051] The obtained double flux-cored welding ring contains 15 wt% flux, of which cesium fluoroaluminate accounts for 5 wt% and potassium fluoroaluminate accounts for 95 wt%. Example

[0052] The double flux-cored ring was prepared using the same method as in Example 1, wherein the proportion of cesium fluoroaluminate was 10 wt% and the proportion of potassium fluoroaluminate was 90 wt%. Example

[0053] The double flux-cored ring was prepared using the same method as in Example 1, wherein the proportion of cesium fluoroaluminate was 15 wt% and the proportion of potassium fluoroaluminate was 85 wt%.

[0054] Comparative Example 1 1. Roll Al88-Si12 aluminum-silicon brazing wire strip into a U-shaped groove, add a mixture of potassium fluoroaluminate flux and cesium fluoroaluminate flux powder, stack the two sides of the U-shaped groove together, and then draw it into a single flux-cored welding wire with a diameter of Φ2.0mm through diameter reduction.

[0055] 2. Use a ring-making machine to make a single flux-cored welding wire into a single flux-cored welding ring with a diameter of Φ2.0*Φ6.9*1 turn.

[0056] The obtained single-core solder ring contains 15 wt% flux, of which cesium fluoroaluminate accounts for 10 wt% and potassium fluoroaluminate accounts for 90 wt%.

[0057] Comparative Example 2 A single flux-cored welding ring was prepared using the same method as in Comparative Example 1, wherein cesium fluoroaluminate accounted for 30 wt% and potassium fluoroaluminate accounted for 70 wt%.

[0058] Comparative Example 3 Single-core welding rings were prepared using the same method as in Comparative Example 1, wherein cesium fluoroaluminate accounted for 50 wt% and potassium fluoroaluminate accounted for 50 wt%.

[0059] Brazing test Using the flux-cored welding rings Φ2.0*Φ6.9*1 rings obtained in the above examples and comparative examples, one end of a 6061 aluminum alloy tube with an outer diameter of Φ7.0 × wall thickness of 1mm × length of 150mm was flared to a depth of 12mm and an inner diameter of 7.15mm. Then, another 6061 aluminum alloy tube with an outer diameter of Φ7.0 × wall thickness of 1mm × length of 150mm was inserted into the flared end to form an assembly. Flame brazing was performed using the flux-cored welding ring, with a weld gap of 0.05mm~0.1mm, a welding heating time of 18s, and air cooling after welding to obtain a brazed sample.

[0060] The samples obtained from the above brazing test were used to conduct brazing performance tests, and the average value of 5 groups of brazed samples was taken. The test results are shown in the table below:

[0061] The above test results demonstrate that the double-cored flux-cored welding ring prepared by this invention exhibits excellent welding performance. The double-cored flux-cored welding ring of this invention, containing 10 wt% cesium fluoroaluminate in the flux, shows superior welding performance for brazing magnesium-aluminum alloy pipe fittings compared to the single-cored flux-cored welding ring containing 50 wt% cesium fluoroaluminate. The filler metal at the weld joint is dense and uniform, resulting in good joint sealing, which meets the requirements for automotive piping applications.

Claims

1. A dual flux-cored welding ring, comprising a seamless flux-cored welding wire with cesium fluoroaluminate flux as the core and a slotted flux-cored welding wire with potassium fluoroaluminate flux as the core, wherein the seamless flux-cored welding wire is sandwiched between two layers of brazing filler metal formed by stacking the slotted flux-cored welding wire to form a joint, the seamless flux-cored welding wire uses brazing filler metal with a lower melting point than the slotted flux-cored welding wire, and the mass ratio of cesium fluoroaluminate flux to potassium fluoroaluminate flux is in the range of 1:3 to 1:

10.

2. The double flux-cored welding ring according to claim 1, characterized in that: Potassium fluoroaluminate fluxes are selected from potassium fluoroaluminate fluxes and potassium fluoroaluminate fluxes with added components.

3. The double flux-cored welding ring according to claim 2, characterized in that: Potassium fluoroaluminate fluxes are selected from potassium fluoroaluminate fluxes containing zinc halide, alkali metal halide, alkaline earth metal halide, alkali metal salts of fluoroaluminate, alkaline earth metal salts of fluoroaluminate, alkali metal salts of zinc fluoroaluminate, alkaline earth metal salts of zinc fluoroaluminate, alkali metal salts of zinc fluoroaluminate, and alkaline earth metal salts of fluorosilicate.

4. The double flux-cored welding ring according to claim 1, characterized in that: Cesium fluoroaluminate fluxes are selected from cesium fluoroaluminate fluxes and cesium fluoroaluminate fluxes with added components.

5. The double flux-cored welding ring according to claim 4, characterized in that: Cesium fluoroaluminate fluxes are selected from potassium fluoroaluminate fluxes containing zinc halide, alkali metal halide, alkaline earth metal halide, alkali metal salts of fluoroaluminate, alkaline earth metal salts of fluoroaluminate, alkali metal salts of zinc fluoroaluminate, alkaline earth metal salts of zinc fluoroaluminate, alkali metal salts of zinc fluoroaluminate, and alkaline earth metal salts of fluorosilicate.

6. The double flux-cored welding ring according to claim 1, characterized in that: The flux content in the double flux-cored solder ring is in the range of 5 wt% to 35 wt%.

7. The double flux-cored welding ring according to claim 1, characterized in that: The filler metal for the slotted filler wire of the double flux-cored welding ring is an aluminum-silicon based filler metal.

8. The double flux-cored welding ring according to claim 1, characterized in that: The seamless flux-cored wire for double flux-cored welding rings uses zinc-aluminum or silicon-aluminum brazing filler metals.

9. The double flux-cored welding ring according to claim 7 or 8, characterized in that: The aluminum-silicon based brazing filler metals are selected from Al-Si alloy brazing filler metals, Al-Si-Ag alloy brazing filler metals, Al-Si-Cu alloy brazing filler metals, Al-Si-Mg alloy brazing filler metals, Al-Si-Zn alloy brazing filler metals, Al-Si-Ti alloy brazing filler metals, Al-Si-Sr alloy brazing filler metals, Al-Si-Ge alloy brazing filler metals, Al-Si-Ce alloy brazing filler metals, Al-Si-Cu-Zn alloy brazing filler metals, Al-Si-Cu-Ni alloy brazing filler metals, Al-Si-Cu-RE alloy brazing filler metals, Al-Si-Ti-Sr alloy brazing filler metals, Al-Si-Ti-Sr-Ce alloy brazing filler metals, Al-Si-Cu-Ni-RE alloy brazing filler metals, Al-Si-Cu-Ni-Sr alloy brazing filler metals, and Al-Si-Ti-Sr-Ce alloy brazing filler metals.

10. A method for preparing a double flux-cored bonding ring according to any one of claims 1 to 9, comprising the following steps: 1) Preparation of seamless flux-cored welding wire with cesium fluoroaluminate flux as the core; 2) Roll the brazing alloy strip into a U-shaped groove, add flux powder, and press seamless flux wire between the two layers of brazing alloy that form the joint on both sides of the U-shaped groove during the process of stacking and joining. Then, draw the wire to make a double flux wire by reducing the diameter. 3) Use a ring-making machine to make double flux-cored welding wire into double flux-cored welding rings.

Images