A brazing method of a titanium-based filler

Abstract

The application discloses a brazing method of titanium-based filler metal and belongs to the technical field of brazing application, and solves the problem of large brittleness and low strength of a brazed joint by using the existing brazing method. The brazing method comprises the following steps: step a: placing the titanium-based filler metal on the surface of a to-be-welded component and fixing and clamping the titanium-based filler metal by a tool clamp; and step b: placing the to-be-welded component with the fixed titanium-based filler metal in a vacuum brazing furnace, brazing and heat-insulating.

Description

Technical Field

[0001] This invention relates to the field of brazing application technology, and in particular to a brazing method for a low-brittle titanium-based brazing filler metal. Background Technology

[0002] Brazing technology, as an important joining method, is widely used in aerospace, electronics, and automotive manufacturing. Titanium and its alloys, due to their excellent strength, corrosion resistance, and specific strength, have found widespread application in modern industry. However, titanium alloys are prone to generating brittle phases during brazing, which affects the mechanical properties of the joint, especially exhibiting significant brittleness at high temperatures. This severely limits the application range of titanium and its alloys.

[0003] Traditional brazing filler metals for titanium alloys primarily consist of Ti, Zr, Cu, and Ni elements. The large amounts of Zr, Al, V, Cu, and Ni readily form brittle compounds during brazing, leading to insufficient strength and toughness in the brazed joint. During titanium alloy brazing, brittle compound phases such as Ti3Al, Ti-V, Ti2Ni, TiNi, and TiCu form at the interface, negatively impacting the fracture toughness and fatigue performance of the joint. Generally, brazed samples exhibit brittle fracture with an elongation after fracture of less than 5%. Although optimizing the brazing process can improve the performance of the brazed joint to some extent, the limitations of the filler metal itself mean that existing titanium-based filler metals still cannot meet the performance requirements of some applications. Summary of the Invention

[0004] In view of the above, the present invention aims to provide a brazing method for low-brittle titanium-based brazing filler metal, in order to solve the problems of high brittleness and low strength of brazed joints using existing brazing methods.

[0005] The objective of this invention is mainly achieved through the following technical solutions:

[0006] A brazing method using titanium-based brazing filler metal includes the following steps:

[0007] Step a: Prepare titanium-based solder;

[0008] Step b: Place the titanium-based brazing filler metal on the surface of the component to be welded and fix it in place using a tooling fixture;

[0009] Step c: Place the component to be brazed, with the titanium-based brazing filler metal fixed on it, in a vacuum brazing furnace, braze, and keep warm;

[0010] In step a, the raw materials for preparing titanium-based brazing filler metal include rare earth elements, and the preparation of titanium-based brazing filler metal is carried out in a vacuum rapid quenching equipment with strong cooling capacity and good cooling uniformity.

[0011] Optionally, in step c, the brazing temperature is 890-980℃ and the holding time is 5-60min.

[0012] Optionally, in step b, the material of the component to be welded includes TA15 titanium alloy.

[0013] Optionally, the titanium-based solder is a low-brittle titanium-based solder, which, by mass percentage, comprises: Zr, 5%-30%, Cu, 10%-15%, Ni, 10%-15%, Nb, 0.5%-3.5%, rare earth elements, 0.1%-0.3%; the balance being Ti and unavoidable trace impurities.

[0014] Alternatively, rare earth elements include one or more of La, Ce, and Y.

[0015] Optionally, the brazing temperature is 900-950℃.

[0016] Optionally, the heat preservation time is 15-25 minutes.

[0017] Optionally, the brazed joint has a tensile strength of 930-950 MPa and an elongation after fracture of 11%-15%.

[0018] Optionally, the typical microstructure of the brazed joint is lamellar, and the lamellar structure accounts for 75%-90%.

[0019] Optionally, in step a, the preparation of the titanium-based solder includes the following steps:

[0020] Step 1: Melt the titanium-based alloy into alloy ingots;

[0021] Step 2: Perform vacuum rapid quenching process in a vacuum rapid quenching equipment to prepare titanium-based brazing filler metal from alloy ingots.

[0022] Optionally, in step 1, the melting temperature is 1200-1400℃.

[0023] Optionally, in the vacuum rapid quenching process of step 2, the melting temperature is 1100-1400℃.

[0024] The vacuum rapid quenching equipment includes a melting furnace vacuum chamber, a rapid quenching vacuum chamber, and a vacuum material hopper; the melting furnace vacuum chamber, the rapid quenching vacuum chamber, and the vacuum material hopper are arranged sequentially.

[0025] The rapid quenching vacuum chamber is equipped with a rotating cooling roller, which has a spindle-shaped internal space through which the cooling medium flows.

[0026] Optionally, the rapid quenching vacuum chamber is further equipped with a rotary tundish system, a strip guide cooling roller, and a strip anti-stacking track, wherein the rotary cooling roller, the rotary tundish system, the strip guide cooling roller, and the strip anti-stacking track are arranged in sequence.

[0027] Optionally, the vacuum chamber of the melting furnace is equipped with a melting device, and the melting device is equipped with a melting crucible.

[0028] Optionally, the smelting apparatus is a medium-frequency melting furnace.

[0029] Optionally, the rotary intermediate tundish system includes multiple rotatable intermediate tundishes, with the rotating cooling roller located below the intermediate tundishes.

[0030] Optionally, a nozzle is provided below the intermediate tundish to spray a cooling medium onto the rotating cooling roller.

[0031] Optionally, the number of intermediate packages is 3-5.

[0032] Optionally, the capacity of the intermediate package is 25-100 kg.

[0033] Optionally, it also includes an online instant polishing device, which is positioned toward the working surface of the rotating cooling roller.

[0034] The rotating cooling roller includes a rotating shaft, flanges, a cooling jacket, a core barrel, and rolling bearings. The cooling jacket is a hollow cylinder without end faces. Both ends of the cooling jacket are connected to a flange, and the other ends of the two flanges are connected to the rotating shaft. The rotating shaft is hollow to allow the cooling medium to flow through. The two flanges and the cooling jacket form a spindle-shaped internal space. The core barrel is located within the spindle-shaped internal space and has gaps between itself and the flanges and the cooling jacket to allow the cooling medium from the rotating shaft to flow through. The shape of the core barrel corresponds to the spindle-shaped internal space, and both ends are connected to the rotating shaft, with rolling bearings at the connection points.

[0035] Optionally, the flange has a tapered structure.

[0036] Optionally, the end of the flange with a larger diameter is connected to the cooling jacket, and the end with a smaller diameter is connected to the rotating shaft.

[0037] Optionally, the inner wall of the flange is provided with a flow guide groove.

[0038] Optionally, the gap between the core barrel and the cooling jacket is 5-10 mm on one side.

[0039] Optionally, the cooling jacket is made of a material with high thermal conductivity.

[0040] Optionally, the inner wall of the cooling jacket is provided with a single-channel or multi-channel spiral groove.

[0041] Optionally, the cross-section of the spiral groove is semi-elliptical, semi-circular, triangular, rectangular, or trapezoidal.

[0042] Optionally, the rotating shaft is hollow inside to allow the cooling medium to flow through; the rotating shaft includes two sections, one for the inflow of the cooling medium and the other for the outflow of the cooling medium; each section of the rotating shaft is connected to the end of the flange with the smaller diameter.

[0043] Optionally, each rotating shaft is open at one end and closed at the other.

[0044] Optionally, each section of the rotating shaft has a through hole on its side wall that communicates with the outside. The through hole is located in the gap between the flange and the core barrel to allow the cooling medium to flow in or out of the rotating shaft and the internal flow path.

[0045] Optionally, the number of through holes is multiple, and the multiple through holes are evenly distributed circumferentially along the rotation axis.

[0046] Optionally, it also includes a locking member, which is disposed at the connection between the core barrel and the rotating shaft to fix the core barrel and the rotating shaft.

[0047] Optionally, the locking element includes a snap-fit.

[0048] Optionally, the core barrel has a cavity structure.

[0049] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0050] a) The brazing method of this invention uses a titanium-based brazing filler metal containing rare earth elements and employs a vacuum rapid quenching device with strong and uniform cooling. By adding rare earth elements to the titanium-based alloy, high-melting-point compounds are formed through the internal oxidation of rare earth elements, reducing the oxygen content of the matrix and improving the high-temperature oxidation resistance and mechanical properties of the alloy. Rare earth elements enhance the mechanical properties of titanium alloys through solid solution and the formation of intermetallic compounds. Introducing rare earth elements provides an effective way to optimize the performance of titanium-based brazing filler metals. While improving the strength (tensile strength of brazed joints 930-950 MPa) and toughness, it reduces the brittleness of brazed joints (elongation after fracture 11%-15%, far higher than the elongation after fracture <5% of existing technologies), broadening the application range of titanium and its alloys, enabling them to be used in applications with high joint performance requirements.

[0051] b) The method for preparing the brazing filler metal of the present invention uses a vacuum rapid quenching equipment with strong cooling intensity and good cooling uniformity, which increases the yield of titanium-based brazing filler metal to amorphous ribbon from about 50% to more than 80%.

[0052] c) By controlling the melting temperature of the alloy ingot during the preparation of titanium-based brazing filler metal and the melting temperature in the vacuum rapid quenching process, this invention further ensures that the strength and toughness of the brazed joint are improved while reducing the brittleness of the brazed joint.

[0053] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of what is particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0054] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0055] Figure 1 The morphology of the amorphous solder strip obtained in Example 1;

[0056] Figure 2 Fracture diagram of a tensile specimen used for tensile strength testing of the brazed joint of Example 1;

[0057] Figure 3 The tensile stress-strain curves for tensile strength testing of the brazed joint of Example 1;

[0058] Figure 4 This is a typical microstructure of the brazed joint in Example 1;

[0059] Figure 5 The morphology of the amorphous solder strip obtained in Example 2;

[0060] Figure 6 Fracture diagram of a tensile specimen used for tensile strength testing of the brazed joint of Example 2;

[0061] Figure 7 The tensile stress-strain curves for tensile strength testing of the brazed joint of Example 2;

[0062] Figure 8 This is a typical microstructure of the brazed joint in Example 2;

[0063] Figure 9 The morphology of the amorphous solder strip obtained in Example 3;

[0064] Figure 10 Fracture diagram of a tensile specimen used for tensile strength testing of the brazed joint of Example 3;

[0065] Figure 11 The tensile stress-strain curves for tensile strength testing of the brazed joint of Example 3;

[0066] Figure 12 This is a typical microstructure of the brazed joint in Example 3;

[0067] Figure 13 This is a schematic diagram of the rotating cooling roller structure of the present invention;

[0068] Figure 14-1 The velocity cloud diagram (longitudinal section) of the flow field during the rotation of the rotating cooling roller core barrel of the present invention;

[0069] Figure 14-2 The velocity cloud diagram (longitudinal section) of the flow field following the rotating cooling roller core barrel of the present invention;

[0070] Figure 15-1 This is a vector diagram (longitudinal section) of the flow field velocity during the rotation of the rotating cooling roller core barrel of the present invention.

[0071] Figure 15-2 This is a vector diagram (longitudinal section) of the flow field velocity following the rotating cooling roller core barrel of the present invention;

[0072] Figure 16 This is a schematic diagram of the vacuum rapid quenching equipment of the present invention.

[0073] Figure label:

[0074] 1-Rotating shaft; 2-Flange; 3-Cooling copper sleeve; 4-Core barrel; 5-Rotary dynamic seal; 6-Rolling bearing; D-Width of spiral groove; h-Height of spiral groove; 7-Vacuum chamber of melting furnace; 8-Smelting device; 9-Rapid quenching vacuum chamber; 10-Vacuum hopper; 11-Online instant grinding device; 12-Rotary cooling roller; 13-Rotary tundish system; 14-Strip guide cooling roller; 15-Strip anti-accumulation track. Detailed Implementation

[0075] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0076] In a first aspect, the present invention provides a method for brazing with titanium-based brazing filler metal, comprising the following steps:

[0077] Step a: Prepare titanium-based solder;

[0078] Step b: Place the titanium-based brazing filler metal on the surface of the component to be welded and fix it in place using a tooling fixture;

[0079] Step c: Place the component to be brazed, with the titanium-based brazing filler metal fixed on it, in a vacuum brazing furnace, braze, and keep warm;

[0080] Step a is carried out in a vacuum rapid quenching equipment with strong cooling capacity and good cooling uniformity.

[0081] Specifically, step a, the preparation of titanium-based solder includes the following steps:

[0082] Step 1: Melt the titanium-based alloy into alloy ingots;

[0083] Step 2: Perform vacuum rapid quenching process in a vacuum rapid quenching equipment to prepare the alloy ingot into an amorphous strip, i.e., titanium-based brazing filler metal.

[0084] Specifically, in step 1, the titanium-based alloy comprises, by mass percentage: Zr, 5%-30%, Cu, 10%-15%, Ni, 10%-15%, Nb, 0.5%-3.5%, rare earth elements, 0.1%-0.3%; the balance being Ti and unavoidable trace impurities.

[0085] Specifically, the rare earth elements in this invention are one or more of La, Ce, and Y.

[0086] The following details the function and dosage selection of the components contained in this invention:

[0087] Zr: The addition of Zr can improve the fluidity of the brazing filler metal and enhance wettability during brazing, thereby facilitating the formation of uniform brazed joints. Therefore, this invention limits the Zr content to 5%-30%.

[0088] Cu: In solder, Cu plays a role in lowering the melting point and increasing fluidity, which helps the solder better fill the joint gap. It also facilitates element diffusion and phase transformation. Therefore, this invention limits the Cu content to 10% to 15%.

[0089] Ni: The addition of Ni can further improve the corrosion resistance and mechanical properties of the brazing filler metal, and enhance the durability and service life of the brazed joint. Therefore, this invention limits the Ni content to 10% to 15%.

[0090] Nb: Adding an appropriate amount of Nb can effectively improve the mechanical properties and corrosion resistance of amorphous alloys, while excessive Nb may lead to a decline in performance. Therefore, this invention limits the Nb content to 0.5% to 3.5%.

[0091] Rare earth elements: Rare earth elements can undergo internal oxidation to form high-melting-point compounds, reducing the oxygen content of the matrix and improving the high-temperature oxidation resistance and mechanical properties of the alloy. In this invention, rare earth elements enhance the mechanical properties of the titanium alloy through solid solution and the formation of intermetallic compounds. Therefore, this invention limits the rare earth element content to 0.1% to 0.3%.

[0092] Ti: Ti element is the balance, and its content is >50%, ensuring that the solder composition is titanium-based.

[0093] To further improve the overall performance of the aforementioned low-brittle titanium-based brazing filler metal, the composition of the aforementioned titanium-based alloy, by mass percentage, can be: Zr, 15%-25%, Cu, 12%-15%, Ni, 12%-15%, Nb, 2%-3%, rare earth elements, 0.1%-0.3%, with the balance being Ti and unavoidable trace impurities.

[0094] Specifically, the microstructure of the aforementioned low-brittle titanium-based brazing filler metal includes: rapid diffusion of Cu and Ni elements into the matrix at the brazing interface, and rapid diffusion of Ti elements into the filler metal. A diffusion layer is first formed near the matrix on both sides, gradually widening with increasing brazing temperature and holding time. Subsequently, β-Ti nucleates and grows in the liquid filler metal. At this point, the remaining liquid phase mainly contains Ti, Zr, Cu, and Ni elements, solidifying to form the (Ti,Zr)2(Cu,Ni) phase. As the temperature decreases, the high-temperature β-Ti gradually undergoes eutectoid decomposition, generating α-Ti distributed in a lamellar pattern. The addition of rare earth elements and Nb elements facilitates the precipitation of lamellar α-Ti, reducing the volume content of the brittle (Ti,Zr)2(Cu,Ni) phase, thereby increasing the joint toughness.

[0095] The design concept of the low-brittle titanium-based brazing filler metal of this invention is as follows: By adding rare earth elements to titanium-based alloys, the internal oxidation of rare earth elements forms high-melting-point compounds, reducing the oxygen content of the matrix and improving the high-temperature oxidation resistance and mechanical properties of the alloy. Rare earth elements enhance the mechanical properties of the titanium alloy through solid solution and the formation of intermetallic compounds. While improving the strength of the brazed joint (tensile strength of 930-950 MPa) and toughness, it reduces the brittleness of the brazed joint (elongation after fracture of 11%-15%, far exceeding the elongation after fracture of <5% in existing technologies), thus broadening the application range of titanium and its alloys and enabling them to be used in applications requiring high joint performance.

[0096] Preferably, in step 1, the melting temperature is 1200-1400℃, for example, 1200℃, 1250℃, 1300℃, 1350℃, or 1400℃.

[0097] The heat preservation time is 10-25 minutes, for example, 10 minutes, 15 minutes, 20 minutes, and 25 minutes.

[0098] Vacuum degree <10 -1 Pa, for example, 1×10 -2 Pa, 3×10 -2 Pa, 5×10 -2 Pa, 7×10 -2 Pa, 9×10 -2 Pa.

[0099] Preferably, in step 2, the melting temperature in the vacuum rapid quenching process is 1100-1400℃, for example, 1100℃, 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, or 1400℃.

[0100] Vacuum degree ≤10 -2 Pa, for example, 1×10 -2 Pa, 1×10 -3 Pa, 5×10 -3 Pa, 7×10 -3 Pa, 9×10 -3 Pa.

[0101] In step 2, the vacuum rapid quenching process is performed in a vacuum rapid quenching equipment. For example... Figure 16 As shown, the vacuum rapid quenching equipment includes a melting furnace vacuum chamber 7, a rapid quenching vacuum chamber 9, and a vacuum material hopper 10 arranged in sequence; the melting furnace vacuum chamber 7, the rapid quenching vacuum chamber 9, and the vacuum material hopper are independent and enclosed structures, and can each perform corresponding operations after being connected to the atmospheric environment without affecting each other.

[0102] The vacuum chamber 7 of the melting furnace is equipped with a melting device 8, and the melting device 8 is equipped with a melting crucible for placing the master alloy.

[0103] The rapid quenching vacuum chamber 9 is equipped with a rotary cooling roller 12, a turntable tundish system 13, a strip guide cooling roller 14, and a strip anti-stacking track 15 in sequence.

[0104] In one specific embodiment, the melting device 8 is a medium-frequency melting furnace. The capacity of the medium-frequency melting furnace is 10-300 kg, preferably 50-150 kg.

[0105] The rotary intermediate bale system 13 comprises 3-5 rotatable independent intermediate bales, each driven by a horizontal disc to rotate and / or stop along the circumference of the disc. A rotating cooling roller 12 is located below the intermediate bales, and each intermediate bale has a nozzle below it to spray cooling medium onto the rotating cooling roller 12. Exemplarily, the capacity of the intermediate bales is 25-100 kg.

[0106] In a preferred embodiment, the vacuum rapid quenching equipment also includes an online instant polishing device 11, which is arranged facing the working surface of the rotating cooling roller 12, and can trim and polish the surface of the rotating cooling roller 12 when the melting device 8 is feeding and melting.

[0107] The strip guide cooling roller 14 is a two-roll adjustable slit structure, which is set at the exit end of the strip after it leaves the rotating cooling roller 12. It controls the flight state of the strip after it leaves the roller, guides the strip through the slit into the strip anti-accumulation track 15, and performs secondary cooling on the strip.

[0108] like Figure 13 As shown, the rotating cooling roller includes a rotating shaft 1, a flange 2, a cooling jacket 3, a core barrel 4, a rotating dynamic seal 5, and a rolling bearing 6.

[0109] Flange 2, core barrel 4 and cooling jacket 3 form an internal flow path, through which the cooling medium flows. Figure 13 The middle arrow indicates the direction of the cooling medium flow.

[0110] The cooling jacket 3 is a hollow cylinder without end faces. Each end of the cooling jacket is connected to a flange 2, and the other ends of the two flanges 2 are connected to a rotating shaft 1. The two flanges 2 and the cooling jacket 3 form a spindle-shaped internal space. The core 4 is located within this internal space, with gaps between it and both flanges 2 and the cooling jacket 3 to allow the cooling medium to flow through. Specifically, as shown... Figure 13 As shown, the longitudinal section of the structure formed by flange 2 and cooling jacket 3 is similar to a hexagon.

[0111] Flange 2 has a tapered structure with a tapered angle of 40°-70°, for example, 40°, 50°, 60°, 70°. The inner wall of flange 2 is provided with guide grooves, which enable the cooling medium (e.g., water) to be quickly distributed after entering the cooling roller.

[0112] Specifically, the larger diameter end of the flange 2 is connected to the cooling jacket 3, and the smaller diameter end is connected to the rotating shaft 1.

[0113] The core barrel 4 has a spindle-shaped sealed cavity structure, the shape of which corresponds to the spindle-shaped internal space. Both ends of the core barrel 4 are connected to the rotating shaft 1. A rolling bearing 6 is fixed at the connection between the core barrel 4 and the rotating shaft 1, which allows the core barrel 4 to be in a follow-up state (water flow) when the rotating shaft 1 and the cooling jacket 3 rotate.

[0114] The flange 2, core barrel 4, and cooling jacket 3 together form a spindle-shaped streamlined internal flow path. The streamlined structural design helps to overcome centrifugal force, reducing the impact of the centrifugal force of the high-speed rotation of the cooling roller on the cooling medium, especially the cooling medium in the annular water channel between the cooling jacket and the core barrel. This facilitates the rapid distribution of the cooling medium through the inlet and its rapid convergence at the outlet through the internal flow path, thereby improving the cooling intensity.

[0115] In a preferred embodiment, the longitudinal section of the core barrel 4 is similar to a hexagon.

[0116] In another embodiment, the rotary cooling roller further includes a locking element (e.g., a snap-fit) to fix the core barrel 4 to the rotating shaft 1. In this case, the core barrel 4 is in a rotating state, that is, the core barrel 4 rotates with the rotating shaft 1. By setting the locking element, the present invention can switch the core barrel 4 between a following state and a rotating state. The cooling intensity of the core barrel 4 in the following state and the rotating state is different (see Table 1), thereby realizing the adjustment of the cooling intensity and expanding the application range of the rotary cooling roller of the present invention.

[0117] Specifically, the rotating shaft 1 is hollow inside to allow the cooling medium to flow through. The rotating shaft 1 comprises two sections: one for the inflow of the cooling medium and the other for its outflow. Each section of the rotating shaft is connected to the smaller diameter end of the flange 2. One end of the rotating shaft 1 is open, and the other end is closed. Each section of the rotating shaft has a through-hole on its side wall, located in the gap between the flange 2 and the core barrel 4. This allows the cooling medium to flow in or out of the rotating shaft and its internal flow path, either flowing into the internal flow path or flowing out of the rotating shaft 1, thus allowing the cooling medium to collect at the outlet after flowing through the internal flow path.

[0118] Specifically, there are multiple through holes, and these through holes are evenly distributed around the rotation axis 1.

[0119] In a preferred embodiment, a rotary dynamic seal 5 is provided at the connection between the core barrel and the rotating shaft to prevent the cooling medium in the internal flow path from flowing into the cavity of the core barrel 4.

[0120] It should be noted that, compared with the solid structure, the hollow structure of the core barrel 4 helps to reduce the weight of the cooling roller, save raw materials, and reduce costs.

[0121] The inner wall of the cooling jacket 3 is provided with single or multiple spiral grooves to form a spiral water channel. Multiple spiral grooves are preferred, for example, 3-5 parallel spiral grooves. In use, this invention increases the system's cooling capacity by controlling the flow direction of the cooling medium to be opposite to the rotation direction of the cooling roller.

[0122] Specifically, the pitch S of the spiral groove is 50-100mm. The cross-section of the spiral groove is semi-elliptical, semi-circular, triangular, rectangular, or trapezoidal. When the cross-section of the spiral groove is semi-elliptical or rectangular, the width-to-height ratio is 2-3.5. This invention, by providing spiral grooves on the inner wall of the cooling jacket 3, can reduce the area (dead zone) where the cooling medium, formed by high-speed rotation, is relatively stationary with the inner surface of the cooling roller when flowing in the spiral channel. The existence of the dead zone causes the cooling medium water to vaporize upon contact with the inner surface of the cooling roller, forming a gas film that hinders heat transfer, and in severe cases (excessive vapor pressure), can easily lead to danger. This invention, by providing spiral grooves on the inner wall of the cooling jacket 3, improves both cooling intensity and production safety.

[0123] The cooling jacket 3 is made of copper, copper alloy, or other materials with high thermal conductivity. The gap between the cooling jacket 3 and the core barrel 4 is 5-10 mm on one side, for example, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm. The gap between the flange 2 and the core barrel 4 is 30-40 mm on one side, for example, 30 mm, 32 mm, 35 mm, 37 mm, 39 mm, or 40 mm.

[0124] The thickness of the prepared amorphous ribbon is 0.02-0.04 mm, for example, 0.02 mm, 0.03 mm, and 0.04 mm. The width of the amorphous ribbon is 40-100 mm, for example, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, and 100 mm.

[0125] In addition, the melting point of the titanium-based brazing filler metal prepared by the above preparation method is 820-878℃, for example, 820℃, 830℃, 840℃, 850℃, 860℃, 870℃, and 878℃.

[0126] Specifically, in step b, the material of the component to be welded is TA15 titanium alloy.

[0127] Specifically, in step c, the brazing temperature is 890-980℃, for example, 890℃, 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, 960℃, 970℃, 980℃, preferably 900-950℃. The holding time is 5-60 minutes, for example, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, preferably 15-25 minutes. The vacuum degree during brazing is ≤1×10⁻⁶. -2 Pa, for example, 1×10 -2 Pa, 5×10 -3 Pa, 7×10 -3 Pa, 9×10-3 Pa.

[0128] This invention achieves a brazing interface that balances strength and toughness by controlling the brazing temperature to 890-980℃ and the holding time to 5-60min, thereby obtaining a brazing quality with low brittleness and high strength.

[0129] Compared with the prior art, the present invention has the following technical effects:

[0130] a) The brazing method of this invention uses a titanium-based brazing filler metal containing rare earth elements and employs a vacuum rapid quenching device with strong and uniform cooling. By adding rare earth elements to the titanium-based alloy, high-melting-point compounds are formed through the internal oxidation of rare earth elements, reducing the oxygen content of the matrix and improving the high-temperature oxidation resistance and mechanical properties of the alloy. Rare earth elements enhance the mechanical properties of titanium alloys through solid solution and the formation of intermetallic compounds. Introducing rare earth elements provides an effective way to optimize the performance of titanium-based brazing filler metals. While improving the strength (tensile strength of brazed joints 930-950 MPa) and toughness, it reduces the brittleness of brazed joints (elongation after fracture 11%-15%, far higher than the elongation after fracture <5% of existing technologies), broadening the application range of titanium and its alloys, enabling them to be used in applications with high joint performance requirements.

[0131] b) The present invention selects La, Ce and Y as rare earth elements, which facilitates the solid dissolution of rare earth elements in other elements in titanium-based alloys and makes it easier to form intermetallic compounds, thereby ensuring the enhancement of the mechanical properties of titanium-based alloys. Furthermore, since the price of La, Ce and Y is lower than that of other rare earth elements, it is beneficial to reduce production costs.

[0132] c) The method for preparing the brazing filler metal of the present invention uses a vacuum rapid quenching device with strong cooling intensity, which increases the yield of titanium-based brazing filler metal to amorphous ribbon from about 50% to more than 80%.

[0133] d) The flange of this invention has a conical structure, which, when connected to a hollow cooling jacket without end faces, forms a spindle-shaped internal space. The core barrel is a spindle-shaped sealed cavity structure, corresponding to the spindle-shaped internal space formed by the flange and the cooling roller, and leaving gaps between it and the flange and the cooling jacket, thereby constructing an internal flow path of a streamlined spindle structure. The streamlined structural design helps to overcome the centrifugal force, reducing the impact of the centrifugal force of the high-speed rotation of the cooling roller on the poor flow of the cooling medium, especially the cooling medium in the annular water channel between the cooling jacket and the core barrel. This facilitates the rapid distribution of the cooling medium through the inlet and its rapid convergence to the outlet through the internal flow path, ensuring that the cooling medium can pass through quickly. On the one hand, it can remove more heat in a short time, achieving efficient heat exchange and thus improving the cooling intensity; on the other hand, it can increase the cooling uniformity and improve the yield of amorphous ribbon to over 80% (the yield of amorphous ribbon in the prior art is about 50%).

[0134] e) By connecting a rolling bearing at the connection end between the core barrel and the rotating shaft, the core barrel can be in a follow-up state when the rotating shaft and cooling jacket rotate. This is equivalent to applying a shear force perpendicular to the centrifugal force to the internal cooling medium. The purpose is to offset part of the centrifugal force, increase the axial movement efficiency of the cooling medium, and improve the cooling intensity of the rotating cooling roller.

[0135] f) By setting a locking element to fix the core barrel to the rotating shaft, the present invention achieves a rotating state for the core barrel, that is, the core barrel rotates with the rotating shaft. The cooling intensity of the core barrel in the following state and the rotating state are different (see Table 1), thereby realizing the adjustment of the cooling intensity and expanding the application range of the rotating cooling roller of the present invention.

[0136] g) By setting a flow guide groove on the inner wall of the flange, the present invention can achieve rapid distribution of the cooling medium, ensuring that the cooling medium can pass through quickly and remove more heat in a short time, thereby achieving the purpose of efficient heat exchange and further improving the cooling intensity.

[0137] h) The present invention provides single or multiple spiral grooves on the inner wall of the cooling jacket. By controlling the flow direction of the cooling medium to be opposite to the rotation direction of the cooling roller, the cooling capacity of the system is increased, thereby improving the cooling intensity.

[0138] i) The cooling roller of the present invention has great promotion and practical value. When applied to vacuum rapid quenching equipment, it can prepare amorphous foil strips of alloy systems that are urgently needed in the aerospace field but do not have strong amorphous forming ability. After its widespread promotion and application, it will generate good economic and social benefits.

[0139] j) The rotating cooling roller in the vacuum rapid quenching equipment of the present invention constructs a spindle-shaped streamlined internal flow path, which helps to overcome the centrifugal force and reduce the impact of the centrifugal force of the high-speed rotation of the cooling roller on the poor flow of the cooling medium inside, especially the cooling medium in the annular water channel between the cooling jacket and the core barrel. This facilitates the rapid distribution of the cooling medium through the inlet and its rapid convergence to the outlet through the internal flow path, ensuring that the cooling medium can pass through quickly. On the one hand, it can remove more heat in a short time, achieving the purpose of efficient heat exchange and thus improving the cooling intensity. On the other hand, it can increase the cooling uniformity and improve the yield of amorphous ribbon to more than 80% (the yield of amorphous ribbon in the prior art is about 50%).

[0140] Examples 1-6

[0141] The following specific embodiments and comparative examples demonstrate the advantages of precise control of the composition and process parameters of the low-brittleness titanium-based brazing filler metal of the present invention.

[0142] Examples 1-6 of the present invention provide a low-brittle titanium-based brazing filler metal, its preparation method and brazing method. The chemical composition of the brazing filler metal in Examples 1-6 is shown in Table 1.

[0143] The preparation method and brazing method of the brazing filler metal in Examples 1-6 include: smelting into an alloy ingot, preparing the alloy ingot into a titanium-based brazing filler metal (amorphous strip) using a vacuum rapid quenching process, fixing the brazing filler metal, brazing, and heat preservation.

[0144] It should be noted that the equipment used in the vacuum rapid quenching process of Examples 1-6 is a vacuum rapid quenching equipment, and the rotating cooling roller in the vacuum rapid quenching equipment is the cooling roller of Example 7.

[0145] The specific process parameters for Examples 1-6 are shown in Table 2; the tensile strength of the brazed joints was tested, and the test results are shown in Table 3.

[0146] Table 1 Chemical composition, wt%

[0147] Example Zr Cu Ni Nb La Ce Y Ti 1 30 15 10 0.5 0.2 0 0 margin 2 20 10 15 1 0 0.1 0 margin 3 20 15 10 3 0 0.2 0.1 margin 4 5 10 15 3.5 0.1 0 0 margin 5 25 15 15 2 0 0.3 0 margin 6 15 12 12 1.5 0 0.1 0.2 margin

[0148] Table 2 Production Process Parameters

[0149]

[0150] Table 3 shows some performance test results.

[0151]

[0152] Figure 1 , Figure 5 and Figure 9 The images show the morphologies of the amorphous solder strips obtained in Examples 1, 2, and 3, respectively. Figure 1 , Figure 5and Figure 9 It is evident that all three types of strips exhibit good strip-forming properties, with continuous strips and no pores.

[0153] Figure 2 , Figure 6 and Figure 10 Fracture diagrams of tensile specimens from brazed joints of Examples 1, 2, and 3, respectively, are shown. Figure 2 , Figure 6 and Figure 10 It is evident that when brazing titanium alloys with the three types of brazing filler metal strips, the corresponding brazed joints all broke off at room temperature after tensile testing, indicating that the brazing performance was equal to or stronger than that of the base metal.

[0154] Figure 3 (3 samples of each component) Figure 7 (3 samples of each component) and Figure 11 (Three samples of each component were taken) Tensile stress-strain curves for the brazed joints of Examples 1, 2, and 3 were obtained, and the average tensile strength is shown in Table 3. Table 3 shows that after brazing with the filler metal of this invention, the tensile strength of the brazed joint is greater than 930 MPa, and the elongation at fracture is greater than 11%. While improving the strength and toughness of the brazed joint, it reduces its brittleness, broadening the application range of titanium and its alloys, enabling them to be used in applications requiring high joint performance.

[0155] Figure 4 , Figure 8 and Figure 12 The typical microstructures of the brazed joints from Examples 1, 2, and 3 are shown respectively. Figure 4 , Figure 8 and Figure 12 As can be seen, the typical microstructure of brazed joints is lamellar. The proportion of lamellar structure is shown in Table 4 below.

[0156] Table 4 Microstructure of the solder

[0157] serial number Microorganism Organizational proportion Example 1 lamellar tissue 75％ Example 2 lamellar tissue 78％ Example 3 lamellar tissue 90％

[0158] The inventors conducted extensive experimental research during the research process, and some poorly performing solutions are now presented as comparative examples.

[0159] Comparative Example 1

[0160] The composition of the titanium-based brazing filler metal in this comparative example is similar to that in Example 2, except that rare earth elements are not added. The specific composition is shown in Table 5 below. The preparation method and brazing method are the same as in Example 2, and will not be repeated here.

[0161] Comparative Example 2

[0162] The composition of the titanium-based brazing filler metal in this comparative example is similar to that in Example 2, except that the content of rare earth elements is 0.5% (not in the range of 0.1%-0.3%). The specific composition is shown in Table 5 below. The preparation method and brazing method are the same as those in Example 2, and will not be repeated here.

[0163] Comparative Example 3

[0164] The composition of the titanium-based brazing filler metal in this comparative example is the same as that in Example 2, except that the melting temperature in step 1 of the preparation method is 1100°C (see Table 6).

[0165] Comparative Example 4

[0166] The composition of the titanium-based brazing filler metal in this comparative example is the same as that in Example 2, except that the melting temperature in step 1 of the preparation method is 1400℃ (see Table 6).

[0167] Comparative Example 5

[0168] The composition of the titanium-based brazing filler metal in this comparative example is the same as that in Example 2, except that the melting temperature in step 2 of the preparation method is 1000℃ (see Table 6).

[0169] Comparative Example 6

[0170] The composition of the titanium-based brazing filler metal in this comparative example is the same as that in Example 2, except that the melting temperature in step 2 of the preparation method is 1500℃ (see Table 6).

[0171] Comparative Example 7

[0172] The composition of the titanium-based brazing filler metal in this comparative example is the same as that in Example 2, except that the brazing temperature is 850°C (see Table 6).

[0173] Comparative Example 8

[0174] The composition of the titanium-based brazing filler metal in this comparative example is the same as that in Example 2, except that the brazing temperature is 1000℃ (see Table 6).

[0175] The main performance test results of the comparative titanium-based brazing filler metal are shown in Table 7.

[0176] Table 5 Chemical composition, wt%

[0177] Comparative Example Zr Cu Ni Nb La Ce Y Ti 1 20 10 15 1 0 0 0 margin 2 20 10 15 1 0.5 0 0 margin 3 20 10 15 1 0 0.1 0 margin

[0178] Table 6 Production Process Parameters

[0179]

[0180]

[0181] Table 7 shows some performance test results.

[0182]

[0183] Comparing the data in Tables 3 and 7, it can be seen that when no rare earth elements are added to the brazing filler metal, or when too many rare earth elements are added (the content is not within the range of 0.1%-0.3%), the strength of the brazed joint after brazing is only 860-870 MPa (far lower than the greater than 930 MPa of the present invention), and the elongation at fracture is only 4.6-5.2% (far lower than the greater than 11% of the present invention). This indicates that too much or too little rare earth element content will reduce the strength and toughness of the brazed joint after brazing. Therefore, this invention, by adding rare earth elements and controlling the rare earth element content to 0.1%-0.3%, can improve the strength (tensile strength of the brazed joint 930-950 MPa) and toughness while reducing the brittleness of the brazed joint (elongation at fracture 11%-15%, far higher than the elongation at fracture <5% of the prior art), thus broadening the application range of titanium and its alloys and enabling them to be used in applications with high joint performance requirements.

[0184] Furthermore, a comparison of the data in Tables 3 and 7 shows that when the melting temperature is too low (not within the range of 1200-1400℃) and the fusion temperature is too low (not within the range of 1100-1400℃), the tensile strength of the brazed joint is only 870MPa and 865MPa (far lower than the greater than 930MPa of this invention), and the elongation at fracture is only 6.1% and 4.9% (far lower than the greater than 11% of this invention). When the melting temperature is too high (not within the range of 1200-1400℃) and the fusion temperature is too high (not within the range of 1100-1400℃), there is no contribution to improving the tensile strength and elongation at fracture of the brazed joint. This proves that the melting temperature and fusion temperature also have a significant impact on the strength and toughness of the brazed joint. By controlling the smelting temperature to 1200-1400℃ and the melting temperature to 1100-1400℃, the strength (tensile strength of brazed joints 930-950MPa) and toughness of brazed joints can be improved, while reducing the brittleness of brazed joints (elongation after fracture 11%-15%, far higher than the elongation after fracture <5% of existing technologies). This broadens the application range of titanium and its alloys, enabling them to be used in applications with high joint performance requirements.

[0185] Furthermore, when the brazing temperature is too low or too high (not within the range of 900-950℃), the tensile strength of the brazed joint is only 867MPa and 862MPa (far lower than the greater than 930MPa of the present invention), and the elongation at break is only 5.5% and 5.0% (far lower than the greater than 11% of the present invention). This proves that the brazing temperature also has a great influence on the strength and toughness of the brazed joint.

[0186] Furthermore, as can be seen from Table 4, the typical microstructure of the brazed joint obtained by using the titanium-based brazing filler metal, preparation method and brazing method of the present invention is lamellar microstructure, and the proportion of lamellar microstructure is as high as 75%-90%, which makes the brazed joint have excellent strength and toughness.

[0187] Example 7 (Spindle-shaped cooling roller, core barrel follows)

[0188] This embodiment uses a rotating cooling roller with a shaft diameter of 100mm, a cooling jacket material of copper, an outer diameter of 380mm, a core barrel outer diameter of 304mm, and four parallel spiral grooves on the inner wall of the copper jacket. The width-to-height ratio of the spiral grooves D / h is 2.5, and the pitch S is 80mm.

[0189] Example 8 (Spindle-shaped cooling roller, core barrel rotating)

[0190] This embodiment is basically the same as embodiment 7, except that it also includes a locking component (bucket) to fix the core barrel 4 to the rotating shaft 1, so that the core barrel is in a rotating state.

[0191] Comparative Example 9 (Right-angled cooling roller, rotating core barrel)

[0192] Compared to Example 7, the structure of the rotating cooling roller is the structure involved in the patent with patent number ZL201621099453.5.

[0193] Under the same simulation conditions, the velocity and temperature fields during the cooling process of the rotating cooling rollers in Examples 7, 8, and Comparative Example 9 were analyzed using finite element simulation. The results are as follows: Figure 14-1 , Figure 14-2 , Figure 15-1 and Figure 15-2 As shown, the simulation data is listed in Table 8.

[0194] Table 8 Simulation Data Analysis Table

[0195]

[0196] As can be seen from the data in Table 8, the outlet velocity of the spindle-shaped cooling roller (Examples 7 and 8) of the present invention is significantly greater than that of the right-angled cooling roller (Comparative Example 9). The faster outlet velocity of the cooling medium after passing through the spindle-shaped copper roller indicates that the cooling medium can remove more heat in a short time, thereby making the outlet temperature of the spindle-shaped cooling roller (Examples 7 and 8) significantly higher than that of the right-angled cooling roller (Comparative Example 9). This proves that the cooling intensity of the spindle-shaped cooling roller is significantly greater than that of the right-angled cooling roller.

[0197] Furthermore, comparing the data from Examples 7 and 8 in Table 8 reveals that, compared to the core barrel rotation (Example 8), the core barrel follow-up (Example 7) has a faster outlet speed and a lower tangential velocity of the cooling medium between the cooling jacket and the core barrel. A lower tangential velocity of the cooling medium between the cooling jacket and the core barrel indicates a smaller effect of centrifugal force. Therefore, it can be concluded that, compared to core barrel rotation (Example 8), core barrel follow-up (Example 7) is more effective in reducing the influence of centrifugal force, improving the axial flow capacity of the cooling medium, further enhancing cooling efficiency, and consequently increasing cooling intensity.

[0198] In addition, by Figure 14-1 It can be seen that when the core barrel is rotating, the cooling water flow rate is relatively fast (red in the cloud diagram), but from... Figure 15-1 It can be further seen that the high speed is due to the large tangential speed, which means it is greatly affected by centrifugal force, ultimately resulting in a slow outlet speed.

[0199] Example 9

[0200] This embodiment is basically the same as embodiment 1, except that the rotating cooling roller in the vacuum rapid quenching equipment is the cooling roller of embodiment 8.

[0201] Comparative Example 10

[0202] This comparative example is basically the same as Example 1, except that the rotating cooling roller in the vacuum rapid quenching equipment is the same as the cooling roller in Comparative Example 9.

[0203] The yields of titanium-based solders (amorphous ribbons) in Examples 1-6, Example 9, and Comparative Example 10 are shown in Table 9.

[0204] Table 9 Yield of Amorphous Ribbons

[0205] serial number Yield / % Example 1 85 Example 2 87 Example 3 88 Example 4 87 Example 5 90 Example 6 86 Example 9 81 Comparative Example 10 48

[0206] As shown in Table 9, the vacuum rapid quenching equipment using spindle-shaped rotating cooling rollers achieves a yield of over 80% (specifically 81%-90%) of amorphous ribbon, while the equipment using right-angled rotating cooling rollers achieves a yield of only 48%. Therefore, the method for preparing the brazing filler metal of this invention, using a vacuum rapid quenching equipment with strong and uniform cooling, increases the yield of titanium-based alloy brazing filler metal (amorphous ribbon) from approximately 50% to over 80%.

[0207] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A brazing method for titanium-based brazing filler metal, characterized in that, Includes the following steps: Step a: Prepare titanium-based solder; Step b: Place the titanium-based brazing filler metal on the surface of the component to be welded and fix it in place using a tooling fixture; Step c: Place the component to be brazed, with the titanium-based brazing filler metal fixed on it, in a vacuum brazing furnace for brazing and heat preservation; In step a, the raw materials for preparing titanium-based brazing filler metal include rare earth elements, and the preparation of titanium-based brazing filler metal is carried out in a vacuum rapid quenching equipment with strong cooling capacity and good cooling uniformity. The titanium-based brazing filler metal is a low-brittle titanium-based brazing filler metal, which, by mass percentage, comprises: Zr, 5%-30%, Cu, 10%-15%, Ni, 10%-15%, Nb, 0.5%-3.5%, rare earth elements, 0.1%-0.3%; the balance being Ti and unavoidable trace impurities. The rare earth elements are one or more of La, Ce, and Y; Rare earth elements enhance the mechanical properties of titanium alloys through solid solution and the formation of intermetallic compounds, improving the strength and toughness of brazed joints while reducing their brittleness. As the temperature decreases, high-temperature β-Ti gradually undergoes eutectoid decomposition, generating α-Ti distributed in a lamellar pattern. The addition of rare earth elements and Nb elements is conducive to the precipitation of lamellar α-Ti, reducing the volume content of the brittle (Ti,Zr)2(Cu,Ni) phase, thereby increasing the joint toughness. The tensile strength of the brazed joint is 930-950 MPa, and the elongation after fracture is 11%-15%. The typical microstructure of brazed joints is lamellar, and the lamellar structure accounts for 75%-90%; The vacuum rapid quenching equipment includes a melting furnace vacuum chamber, a rapid quenching vacuum chamber, and a vacuum material hopper; the melting furnace vacuum chamber, the rapid quenching vacuum chamber, and the vacuum material hopper are arranged sequentially. The rapid quenching vacuum chamber is equipped with a rotating cooling roller, which has a spindle-shaped internal space through which the cooling medium flows. The rotary cooling roller is used to improve the yield of amorphous ribbon. The rotary cooling roller includes a rotating shaft, a flange, a cooling jacket, a core barrel, and a rolling bearing. The cooling jacket is a hollow cylinder without end faces. Each end of the cooling jacket is connected to a flange, and the other ends of the two flanges are connected to the rotating shaft. The rotating shaft is hollow inside to allow the cooling medium to flow through. The two flanges and the cooling jacket form a spindle-shaped internal space. The core barrel is located in the spindle-shaped internal space and has gaps between itself and the flanges and the cooling jacket, thereby creating an internal flow path of the spindle-shaped streamline structure for the cooling medium from the rotating shaft to flow through. The streamlined structural design helps to overcome the centrifugal force and can reduce the impact of the centrifugal force of the high-speed rotation of the cooling roller on the poor flow of the cooling medium. The outer shape of the core barrel corresponds to the spindle-shaped internal space, and its two ends are respectively connected to the rotating shaft, with rolling bearings provided at the connection points; It also includes a locking element, which is located at the connection between the core barrel and the rotating shaft to fix the core barrel and the rotating shaft.

2. The brazing method according to claim 1, characterized in that, Step a, the preparation of titanium-based solder includes the following steps: Step 1: Melt the titanium-based alloy into alloy ingots; Step 2: Perform vacuum rapid quenching process in a vacuum rapid quenching equipment to prepare titanium-based brazing filler metal from alloy ingots.

3. The brazing method according to claim 2, characterized in that, In step 1, the melting temperature is 1200-1400℃.

4. The brazing method according to claim 2, characterized in that, In the vacuum rapid quenching process of step 2, the melting temperature is 1100-1400℃.

5. The brazing method according to claim 1, characterized in that, In step c, the brazing temperature is 890-980℃ and the holding time is 5-60 minutes.

6. The brazing method according to claim 1, characterized in that, In step c, the brazing temperature is 900-950℃.

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