Friction welding method for dissimilar metal with large melting point difference

Abstract

The invention provides a large-melting-point-difference dissimilar metal friction welding method, which relates to the field of solid-phase welding, and comprises the following steps: S01, weldment processing; s02, a hot dip coating brazing filler metal layer is prepared on the surface of the titanium alloy weldment, the aluminum alloy weldment is pretreated, and a device composed of a heatable brazing filler metal groove and a sealing cover is adopted for hot dip coating of the titanium alloy weldment; s03, tool machining is carried out; s04, tool installation and weldment pre-clamping are carried out; s05, radial friction welding is carried out; and S06, post-welding treatment is conducted. According to the method, radial friction welding is carried out on the titanium-aluminum dissimilar metal with the large melting point difference, so that effective and high-strength connection of the titanium-aluminum dissimilar metal is achieved, and the problems that residual stress is large, cracks are likely to be generated in welding seams, and the joint connection strength is low in diameter connection of the titanium-aluminum dissimilar metal are solved; and it is ensured that the titanium-aluminum composite plays the excellent characteristics of high strength, low weight, low cost and the like of titanium and aluminum materials at the same time.

Description

[0001] The present invention is a divisional application of patent application number 202211064717.3, and the invention name is “A method for radial friction brazing of titanium and aluminum dissimilar metals”. Technical Field

[0002] The invention relates to the technical field of solid phase welding, and in particular to a friction welding method for dissimilar metals with a large melting point difference. Background Art

[0003] Both titanium alloys and aluminum alloys are widely used in aerospace, shipbuilding, vehicle engineering and other fields. Titanium alloy is an alloy based on titanium with other elements added. It has the advantages of high strength, low density, strong fatigue resistance, high corrosion resistance, excellent high temperature resistance, excellent biocompatibility, low thermal expansion coefficient, and good shock resistance. Aluminum alloy has the advantages of light weight and low density, high strength, excellent processing performance (i.e. good casting performance, easy deformation processing, excellent machining performance, etc.), good corrosion resistance, and good thermal conductivity. At present, some fields have conducted research on connecting titanium alloys and aluminum alloys to form a composite structure to give full play to their excellent properties; however, due to the large difference in melting points between titanium alloys and aluminum alloy tubes (usually around 1000°C) and the low solubility of titanium in aluminum, some low-melting-point elements in the aluminum alloy will burn and evaporate during the fusion welding process to connect titanium alloys and aluminum alloys, resulting in the formation of a large number of brittle intermetallic compounds at the joints, affecting the mechanical properties of the welded joints; and there are large differences in the physical properties of titanium and aluminum metals such as the linear expansion coefficient and thermal conductivity, which makes them have different deformation capabilities during the heating and cooling processes. After welding titanium and aluminum metals, there will be large residual stresses in the welded joints, resulting in cracks in the welds, further affecting the mechanical properties of the welded joints; in addition, titanium is also very easy to react with oxygen, nitrogen, hydrogen and other elements at high temperatures to undergo gettering reactions, which in turn causes oxidation of the aluminum alloy and the welds, reducing the mechanical properties and welding strength of the welded joints. That is, the difficulty of welding between titanium alloy and aluminum alloy, the complex processing technology, and the poor mechanical properties after welding seriously restrict the preparation of titanium-aluminum composite structures, and then restrict the application conditions and fields of titanium-aluminum composite structures. It can be seen that how to achieve effective and high-strength connection between titanium alloy and aluminum alloy has become one of the research difficulties in the field of alloys at home and abroad. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a method for friction welding of dissimilar metals with a large melting point difference. The method is aimed at radial friction welding of titanium-aluminum dissimilar metal ring / tube and ring / rod components, and can achieve high-strength connection of titanium-aluminum dissimilar metals and effectively avoid the problem of poor mechanical properties of titanium-aluminum dissimilar metal welded joints.

[0005] The purpose of the present invention is achieved through the following technical solutions: A friction welding method for dissimilar metals with a large melting point difference, characterized in that it specifically comprises the following steps: S01. Processing of weldments of titanium alloy components and aluminum alloy components; S02. Preparation of hot-dip brazing layer on the surface of titanium alloy weldments and pretreatment of aluminum alloy weldments; S03. Processing of rotary clamping tooling and radial pressurizing tooling according to the sizes of titanium alloy weldments and aluminum alloy weldments coated with brazing layer on the surface; S04. Installation of rotary clamping tooling on the main shaft of friction welding machine, installation of radial pressurizing tooling on the moving slide of friction welding machine, and pre-clamping of titanium alloy weldments and aluminum alloy weldments coated with brazing layer on the surface by rotary clamping tooling and radial pressurizing tooling respectively; S05. Setting welding parameters on the control interface of friction welding machine, starting friction welding machine, and completing friction welding processes of friction, upsetting and pressure holding of weldments; S06. Post-weld processing.

[0006] For further optimization, the titanium alloy component is a rod-shaped or tubular component, and the aluminum alloy component is a ring-shaped component.

[0007] For further optimization, the specific dimensions of the weldment processing in step S01 are: the titanium alloy component is processed into a weldment with an outer diameter D of Φ20mm~Φ160mm and a length L of 50mm~300mm; the aluminum alloy component is processed into a weldment with an inner diameter d of D+(1~2)mm, a wall thickness t of 8mm~20mm, and a width w of 3mm~30mm.

[0008] For further optimization, the specific steps of preparing the brazing material layer on the surface of the titanium alloy weldment in step S02 are: S21. The surface of the titanium alloy weldment is polished with sandpaper to remove the oxide film and burrs on the surface of the titanium alloy, and the surface of the titanium alloy weldment is degreased after polishing; S22. After performing step S21, the titanium alloy weldment is immersed in an activation solution at 50-60°C and kept warm for 20-25 minutes to complete the activation treatment; S23. After the activation treatment, the titanium alloy weldment is vertically immersed in a solder liquid at 730-800°C and kept warm for 5-10 minutes, and the titanium alloy weldment is kept rotating around its own axis to complete the hot-dip solder treatment; S24. The hot-dip-plated titanium alloy weldment is placed in a heat treatment furnace and kept warm at 800-1000°C for 3-6 hours to complete the thermal diffusion treatment, and finally a titanium alloy weldment with a surface uniformly coated with a solder layer is obtained.

[0009] For further optimization, the activation solution is a chromium-fluorine activation solution, and its formula is CrO 3 : 35~45g / L, 40% HF solution: 20~30ml / L; the solder liquid adopts Al-10Si-0.1Re multi-alloy solder; the rotation speed of the titanium alloy weldment around its own axis is 50~200r / min.

[0010] As further optimized, the thickness of the brazing filler metal layer finally obtained on the surface of the titanium alloy weldment in step S24 is 0.05-0.20 mm.

[0011] Before hot-dip soldering, the present invention firstly performs activation treatment with chromium-fluorine activation solution under low temperature conditions, thereby forming a fluorinated film (specifically TiF 3 ), one is to prevent the titanium alloy surface from reacting with oxygen, nitrogen, hydrogen and other elements under the high temperature conditions of hot dip plating, causing oxidation of the titanium alloy surface and forming an oxide film that is easy to fall off; the other is to serve as a transition layer between the brazing material layer and the substrate to increase the bonding strength between the subsequently obtained brazing material layer and the titanium alloy weldment. Then, the titanium alloy weldment is subjected to "self-rotation" (i.e. rotation around its own axis) hot dip plating treatment in the brazing liquid. Through the self-rotation of the titanium alloy weldment, firstly, the brazing liquid is mechanically stirred in real time during the plating process to increase the atomic diffusion rate between the brazing liquid and the titanium alloy weldment, thereby ensuring the density and uniformity of the brazing layer and improving the bonding strength between the brazing layer and the surface layer of the titanium alloy weldment (specifically the fluorinated film layer); secondly, through the centrifugal effect generated by the "self-rotation" of the titanium alloy weldment, the surface tension difference of the titanium alloy weldment at different positions in the plating liquid is balanced (in the hot dip plating process, due to the influence of surface tension, the thickness of the brazing layer of the titanium alloy weldment tends to decrease from the bottom to the top, resulting in uneven overall thickness of the plating layer, thereby affecting the performance of the welded joint), further ensuring the uniformity of the brazing layer thickness. Finally, through thermal diffusion treatment, the atomic movement between the brazing material layer and the surface of the titanium alloy weldment is promoted, which is conducive to the formation of a diffusion layer between the brazing material layer and the surface of the titanium alloy weldment, and effectively fills the vacancies in the crystals generated by the hot dip plating process, further ensuring the compactness of the brazing material layer and the bonding strength between the brazing material layer and the surface of the titanium alloy weldment. This application prepares a brazing material layer with high bonding strength to the surface of the titanium alloy weldment. First, it prevents the brazing material layer from falling off or being squeezed into the welding burr under the action of the huge rotational friction shear force between the titanium alloy weldment and the aluminum alloy weldment during welding, resulting in direct contact welding between the titanium alloy weldment and the aluminum alloy weldment, affecting the welding quality and the strength of the welded joint; second, the brazing material layer has a lower melting point than the aluminum alloy and has good compatibility with the aluminum alloy. It is easy to react with the aluminum alloy during friction welding to form a solid solution or a dispersion strengthening phase, which can effectively inhibit the growth of brittle intermetallic compounds between the titanium alloy and the aluminum alloy, and at the same time significantly refines the size of the brittle phase, improves the interface bonding, and further improves the strength of the welded joint.

[0012] For further optimization, the pre-treatment of the aluminum alloy weldment in step S02 includes removing oxide film, burrs and oil from the aluminum alloy weldment.

[0013] For further optimization, the welding parameters of the friction welding machine in step S05 are: friction speed 900r / min~2300r / min, friction pressure 2MPa~5MPa, upsetting speed 400r / min~1000r / min, upsetting pressure 5MPa~12MPa.

[0014] For further optimization, the specific steps of the post-weld processing in step S06 are: first loosen the radial pressurizing fixture, move the slide backward, then loosen the rotary clamping fixture, and remove the welded parts of the titanium alloy and the aluminum alloy; then use machining to remove excess aluminum alloy welding flash and coating.

[0015] The following are the technical effects of the solution of the present invention: The present invention prepares a uniform and dense multi-alloy brazing filler metal layer on the surface of the titanium alloy weldment through the treatment processes of activation treatment of the titanium alloy weldment, "self-rotation" hot-dip plating treatment of the titanium alloy weldment and thermal diffusion treatment, and the bonding strength between the brazing filler metal layer and the titanium alloy substrate is high; then, the titanium alloy weldment with the surface coated with the brazing filler metal layer and the aluminum alloy weldment are radially friction welded, and through the compatibility between the brazing filler metal layer and the aluminum alloy, not only the growth of brittle intermetallic compounds at the titanium-aluminum welding interface is effectively suppressed, the size of the brittle phase is significantly refined, and other characteristics, but also the problems of large residual stress in the joint after welding the titanium alloy and the aluminum alloy weldment, easy cracking of the weld, low joint connection strength, etc. are avoided, thereby achieving high-strength connection between titanium alloy and aluminum alloy dissimilar metal ring / tubular or ring / rod-shaped components, effectively expanding the application field of titanium-aluminum composite components, reducing the application conditions and costs of titanium-aluminum composite components, and promoting the further development of titanium alloy and aluminum alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of radial friction brazing of a titanium alloy weldment and an aluminum alloy weldment in an embodiment of the present invention.

[0017] Figure 2 This is a flow chart of radial friction brazing in an embodiment of the present invention; wherein: Figure 2 (a) is a schematic diagram of the structure before welding; Figure 2 (b) is a schematic diagram of the welding structure; Figure 2 (c) is a schematic diagram of the structure after welding.

[0018] Figure 3 This is a diagram of the device for preparing the solder layer in the embodiment of the present application.

[0019] Among them, 10, titanium alloy weldment; 20, solder layer; 30, aluminum alloy weldment; 11, heatable solder tank; 110, first rotating support; 12, sealing cover; 121, second rotating support; 122, rotating shaft. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0021] Embodiment 1: A friction welding method for dissimilar metals with a large melting point difference, used for a rod-shaped titanium alloy component and a ring-shaped aluminum alloy component, characterized in that it specifically comprises the following steps: S01. Processing of weldments of titanium alloy components and aluminum alloy components: Process the titanium alloy components into weldments with an outer diameter D of Φ20 mm and a length L of 50 mm; process the aluminum alloy components into weldments with an inner diameter d of 21 mm, a wall thickness t of 8 mm, and a width w of 3 mm.

[0022] S02, preparing a hot-dip brazing layer 20 on the surface of the titanium alloy weldment 10, the specific steps are as follows: S21, the surface of the titanium alloy weldment 10 is polished with sandpaper to remove the oxide film and burrs on the surface of the titanium alloy, and the surface of the titanium alloy weldment 10 is degreased after polishing (it can be cleaned with alcohol, acetone, etc.); S22, after performing step S21, the titanium alloy weldment 10 is immersed in an activation solution at 50°C and kept warm for 20 minutes to complete the activation treatment; the activation solution is a chromium-fluorine activation solution, and its formula is CrO 3 : 35g / L, 40% HF solution: 20ml / L; S23, after the activation treatment, the titanium alloy weldment 10 is vertically immersed in the 730℃ solder liquid for 5min, and the titanium alloy weldment 10 is kept rotating around its own axis to complete the hot dip solder treatment; the solder liquid adopts Al-10Si-0.1Re multi-alloy solder (that is, Si, Re and pure aluminum are mixed according to the ratio of 10% by mass, 0.1% by mass and the rest is pure aluminum, and then directly melted into liquid to form a multi-alloy solder liquid); the rotation speed of the titanium alloy weldment 10 around its own axis is 50r / min; S24, the hot dipped titanium alloy weldment 10 is placed in a heat treatment furnace and kept at 800℃ for 3h to complete the thermal diffusion treatment, and finally a titanium alloy weldment 10 with a solder layer 20 uniformly coated on the surface is obtained; wherein the thickness of the solder layer 20 is 0.05mm.

[0023] Pretreatment of the aluminum alloy weldment 30: remove the oxide film, burrs and oil from the aluminum alloy weldment 30; sandpaper can be used to grind the surface of the aluminum alloy to remove the oxide film and burrs, and alcohol, acetone and the like can be used for degreasing.

[0024] S03. According to the sizes of the titanium alloy weldment 10 and the aluminum alloy weldment 30 coated with the brazing material layer 20 on the surface, a rotary clamping tool and a radial pressurizing tool are respectively manufactured (the structures of the rotary clamping tool and the radial pressurizing tool can both adopt the structural types of the common radial friction welding process in the art, but the corresponding sizes are improved and processed according to the sizes of the specific workpieces, which can be understood by those skilled in the art).

[0025] S04. The rotary clamping tool is installed on the main shaft of the friction welding machine, and the radial pressurizing tool is installed on the movable slide of the friction welding machine. The rotary clamping tool and the radial pressurizing tool are used to pre-clamp the titanium alloy weldment 10 and the aluminum alloy weldment 30 with the surface coated with the brazing material layer 20 respectively.

[0026] S05. Set the welding parameters on the control interface of the friction welding machine, set the friction speed to 2300r / min, the friction pressure to 2MPa, the upsetting speed to 1000r / min, and the upsetting pressure to 5MPa; start the friction welding machine, and move the slide table to fast forward first and then work forward under the action of the axial main oil cylinder, and move the aluminum alloy weldment 30 in the radial pressurizing fixture to the welding position of the titanium alloy weldment 10 with a surface coated with a brazing material layer 20. The main shaft of the friction welding machine starts to rotate and speed up, and the titanium alloy weldment 10 with a surface coated with a brazing material layer 20 in the rotating clamping fixture rotates accordingly. When the main shaft speed increases to the friction speed of 2300r / min, the main shaft speed increases to 1000r / min, and the main shaft speed increases to 1000r / min. / min, the friction welding machine spindle cuts off power, and the aluminum alloy weldment 30 produces static radial shrinkage deformation under the radial friction pressure of 2MPa of the radial pressurizing tooling, and contacts and rubs against the outer surface of the titanium alloy weldment 10 coated with a brazing layer 20 on the surface. The flywheel's rotational kinetic energy is converted into friction heat to put the aluminum alloy side of the welding surface in a thermoplastic state. As the flywheel's rotational kinetic energy is consumed, the friction speed drops to the upsetting speed of 1000r / min, and the aluminum alloy weldment 30 clamped in the radial pressurizing tooling produces an upsetting brake under the radial upsetting pressure of 5MPa, maintains pressure, and completes the welding process.

[0027] S06, post-weld processing: first loosen the radial pressurizing fixture, move the slide backward, then loosen the rotary clamping fixture, and remove the welded parts of the titanium alloy and the aluminum alloy; finally, use machining to remove the excess aluminum alloy welding flash and coating.

[0028] Embodiment 2: A friction welding method for dissimilar metals with a large melting point difference, used for a tubular titanium alloy component and an annular aluminum alloy component, characterized in that it specifically comprises the following steps: S01. Processing of weldments of titanium alloy components and aluminum alloy components: Process the titanium alloy components into weldments with an outer diameter D of Φ90 mm and a length L of 180 mm; process the aluminum alloy components into weldments with an inner diameter d of 91.5 mm, a wall thickness t of 14 mm, and a width w of 16 mm.

[0029] S02, preparing a hot-dip brazing layer 20 on the surface of the titanium alloy weldment 10, the specific steps are as follows: S21, the surface of the titanium alloy weldment 10 is polished with sandpaper to remove the oxide film and burrs on the titanium alloy surface, and the surface of the titanium alloy weldment 10 is degreased after polishing (it can be cleaned with alcohol, acetone, etc.); S22, after performing step S21, the titanium alloy weldment 10 is immersed in an activation solution at 55°C and kept warm for 22 minutes to complete the activation treatment; the activation solution is a chromium-fluorine activation solution, and its formula is CrO 3 : 40g / L, 40% HF solution: 25ml / L; S23, after activation treatment, vertically immerse the titanium alloy weldment 10 in 760℃ solder liquid for 7min, and keep the titanium alloy weldment 10 rotating around its own axis to complete the hot dip solder treatment; Al-10Si-0.1Re multi-alloy solder is used in the solder liquid (that is, Si, Re and pure aluminum are mixed in a ratio of 10% by mass, 0.1% by mass and the rest is pure aluminum, and then directly melted into liquid to form a multi-alloy solder liquid); the rotation speed of the titanium alloy weldment 10 rotating around its own axis is 120r / min; S24, place the hot dipped titanium alloy weldment 10 in a heat treatment furnace, and keep it at 900℃ for 4.5h to complete the thermal diffusion treatment, and finally obtain a titanium alloy weldment 10 with a solder layer 20 uniformly coated on the surface; wherein the solder layer 20 has a thickness of 0.12mm.

[0030] Pretreatment of the aluminum alloy weldment 30: remove the oxide film, burrs and oil from the aluminum alloy weldment 30; sandpaper can be used to grind the surface of the aluminum alloy to remove the oxide film and burrs, and alcohol, acetone and the like can be used for degreasing.

[0031] S03. According to the sizes of the titanium alloy weldment 10 and the aluminum alloy weldment 30 coated with the brazing material layer 20 on the surface, a rotary clamping tool and a radial pressurizing tool are respectively manufactured (the structures of the rotary clamping tool and the radial pressurizing tool can both adopt the structural types of the common radial friction welding process in the art, but the corresponding sizes are improved and processed according to the sizes of the specific workpieces, which can be understood by those skilled in the art).

[0032] S04. The rotary clamping tool is installed on the main shaft of the friction welding machine, and the radial pressurizing tool is installed on the movable slide of the friction welding machine. The rotary clamping tool and the radial pressurizing tool are used to pre-clamp the titanium alloy weldment 10 and the aluminum alloy weldment 30 with the surface coated with the brazing material layer 20 respectively.

[0033] S05. Set the welding parameters in the control interface of the friction welding machine, set the friction speed to 1600r / min, the friction pressure to 3.5MPa, the top forging speed to 700r / min, and the top forging pressure to 8.5MPa; turn on the friction welding machine, and move the slide table to fast forward first and then work forward under the action of the axial main oil cylinder, and move the aluminum alloy weldment 30 in the radial pressurizing fixture to the welding position of the titanium alloy weldment 10 with a surface coated with a brazing material layer 20. The main shaft of the friction welding machine starts to rotate and speed up, and the titanium alloy weldment 10 with a surface coated with a brazing material layer 20 in the rotating clamping fixture rotates accordingly. When the main shaft speed increases to the friction speed of 1600r / min, the main shaft speed increases to 1600r / min. / min, the friction welding machine spindle cuts off power, and the aluminum alloy weldment 30 produces static radial shrinkage deformation under the radial friction pressure of 3.5MPa of the radial pressurizing tooling, and contacts and rubs against the outer surface of the titanium alloy weldment 10 coated with a brazing layer 20 on the surface. The flywheel's rotational kinetic energy is converted into friction heat to put the aluminum alloy side of the welding surface in a thermoplastic state. As the flywheel's rotational kinetic energy is consumed, the friction speed drops to the upsetting speed of 700r / min, and the aluminum alloy weldment 30 clamped in the radial pressurizing tooling produces upsetting brakes under the radial upsetting pressure of 8.5MPa, maintains pressure, and completes the welding process.

[0034] S06, post-weld processing: first loosen the radial pressurizing fixture, move the slide backward, then loosen the rotary clamping fixture, and remove the welded parts of the titanium alloy and the aluminum alloy; finally, use machining to remove the excess aluminum alloy welding flash and coating.

[0035] Embodiment 3: A friction welding method for dissimilar metals with a large melting point difference, used for a rod-shaped titanium alloy component and a ring-shaped aluminum alloy component, characterized in that it specifically comprises the following steps: S01. Processing of weldments of titanium alloy components and aluminum alloy components: Process the titanium alloy components into weldments with an outer diameter D of Φ160 mm and a length L of 300 mm; process the aluminum alloy components into weldments with an inner diameter d of 162 mm, a wall thickness t of 20 mm, and a width w of 30 mm.

[0036] S02, preparing a hot-dip brazing layer 20 on the surface of the titanium alloy weldment 10, the specific steps are as follows: S21, the surface of the titanium alloy weldment 10 is polished with sandpaper to remove the oxide film and burrs on the surface of the titanium alloy, and the surface of the titanium alloy weldment 10 is degreased after polishing (it can be cleaned with alcohol, acetone, etc.); S22, after performing step S21, the titanium alloy weldment 10 is immersed in an activation solution at 60°C and kept warm for 25 minutes to complete the activation treatment; the activation solution is a chromium-fluorine activation solution, and its formula is CrO 3: 45g / L, 40% HF solution: 30ml / L; S23, after the activation treatment, the titanium alloy weldment 10 is vertically immersed in the 800℃ solder liquid for 10min, and the titanium alloy weldment 10 is kept rotating around its own axis to complete the hot-dip solder treatment; the solder liquid adopts Al-10Si-0.1Re multi-alloy solder (that is, Si, Re and pure aluminum are mixed according to the ratio of 10% by mass, 0.1% by mass and the rest is pure aluminum, and then directly melted into liquid to form a multi-alloy solder liquid); the rotation speed of the titanium alloy weldment 10 around its own axis is 200r / min; S24, the hot-dip titanium alloy weldment 10 is placed in a heat treatment furnace and kept at 1000℃ for 6h to complete the thermal diffusion treatment, and finally a titanium alloy weldment 10 with a solder layer 20 uniformly coated on the surface is obtained; wherein the solder layer 20 has a thickness of 0.20mm.

[0037] Pretreatment of the aluminum alloy weldment 30: remove the oxide film, burrs and oil from the aluminum alloy weldment 30; sandpaper can be used to grind the surface of the aluminum alloy to remove the oxide film and burrs, and alcohol, acetone and the like can be used for degreasing.

[0038] S03. According to the sizes of the titanium alloy weldment 10 and the aluminum alloy weldment 30 coated with the brazing material layer 20 on the surface, a rotary clamping tool and a radial pressurizing tool are respectively manufactured (the structures of the rotary clamping tool and the radial pressurizing tool can both adopt the structural types of the common radial friction welding process in the art, but the corresponding sizes are improved and processed according to the sizes of the specific workpieces, which can be understood by those skilled in the art).

[0039] S04. The rotary clamping tool is installed on the main shaft of the friction welding machine, and the radial pressurizing tool is installed on the movable slide of the friction welding machine. The rotary clamping tool and the radial pressurizing tool are used to pre-clamp the titanium alloy weldment 10 and the aluminum alloy weldment 30 with the surface coated with the brazing material layer 20 respectively.

[0040] S05. Set welding parameters on the control interface of the friction welding machine, set the friction speed to 900r / min, the friction pressure to 5MPa, the top forging speed to 400r / min, and the top forging pressure to 12MPa; start the friction welding machine, and move the slide table to fast forward first and then work forward under the action of the axial main oil cylinder, and move the aluminum alloy weldment 30 in the radial pressurizing fixture to the welding position of the titanium alloy weldment 10 with a surface coated with a brazing material layer 20. The main shaft of the friction welding machine starts to rotate and speed up, and the titanium alloy weldment 10 with a surface coated with a brazing material layer 20 in the rotating clamping fixture rotates accordingly. When the main shaft speed increases to the friction speed of 900r / min, the friction welding machine spindle cuts off power, the aluminum alloy weldment 30 produces static radial shrinkage deformation under the radial friction pressure of 5MPa of the radial pressurizing tooling, and contacts and rubs against the outer surface of the titanium alloy weldment 10 coated with a brazing layer 20 on the surface. The flywheel's rotational kinetic energy is converted into friction heat to put the aluminum alloy side of the welding surface in a thermoplastic state. As the flywheel's rotational kinetic energy is consumed, the friction speed drops to the upsetting speed of 400r / min, and the aluminum alloy weldment 30 clamped in the radial pressurizing tooling produces an upsetting brake under the radial upsetting pressure of 12MPa, maintains pressure, and completes the welding process.

[0041] S06, post-weld processing: first loosen the radial pressurizing fixture, move the slide backward, then loosen the rotary clamping fixture, and remove the welded parts of the titanium alloy and the aluminum alloy; finally, use machining to remove the excess aluminum alloy welding flash and coating.

[0042] Comparative Example 1: A method for welding dissimilar metals: S01. Processing of weldments of titanium alloy components and aluminum alloy components: Process the titanium alloy components into weldments with an outer diameter D of Φ160 mm and a length L of 300 mm; process the aluminum alloy components into weldments with an inner diameter d of 162 mm, a wall thickness t of 20 mm, and a width w of 30 mm.

[0043] S02, the surface of the titanium alloy weldment 10 is polished with sandpaper to remove the oxide film and burrs on the surface of the titanium alloy, and the surface of the titanium alloy weldment 10 is degreased after polishing (it can be cleaned with alcohol, acetone, etc.); Pretreatment of the aluminum alloy weldment 30: remove the oxide film, burrs and oil from the aluminum alloy weldment 30; sandpaper can be used to grind the surface of the aluminum alloy to remove the oxide film and burrs, and alcohol, acetone and the like can be used for degreasing.

[0044] S03. A rotary clamping tool and a radial pressurizing tool are respectively manufactured according to the sizes of the titanium alloy weldment 10 and the aluminum alloy weldment 30 (the structures of the rotary clamping tool and the radial pressurizing tool can both adopt the structural types commonly used in the radial friction welding process in the art, but are improved and processed to corresponding sizes according to the sizes of the specific workpieces, which can be understood by those skilled in the art).

[0045] S04. The rotary clamping tool is installed on the main shaft of the friction welding machine, and the radial pressurizing tool is installed on the movable slide of the friction welding machine. The rotary clamping tool and the radial pressurizing tool are used to pre-clamp the titanium alloy weldment 10 and the aluminum alloy weldment 30 respectively.

[0046] S05. Set welding parameters on the control interface of the friction welding machine, set the friction speed to 900r / min, the friction pressure to 5MPa, the upsetting speed to 400r / min, and the upsetting pressure to 12MPa; start the friction welding machine, and the movable slide first fast-forwards and then advances under the action of the axial main oil cylinder, and move the aluminum alloy weldment 30 in the radial pressurizing fixture to the welding position of the titanium alloy weldment 10. The main shaft of the friction welding machine starts to rotate and speed up, and the titanium alloy weldment 10 in the rotary clamping fixture rotates accordingly. When the main shaft speeds up to the friction speed of 900r / min, The power of the friction welding machine spindle is cut off, and the aluminum alloy weldment 30 produces static radial shrinkage deformation under the radial friction pressure of 5MPa of the radial pressurizing tooling, and contacts and rubs against the outer surface of the titanium alloy weldment 10. The rotational kinetic energy of the flywheel is converted into friction heat, making the aluminum alloy side of the welding surface in a thermoplastic state. As the rotational kinetic energy of the flywheel is consumed, the friction speed drops to the upsetting speed of 400r / min. The aluminum alloy weldment 30 clamped in the radial pressurizing tooling produces upsetting brake under the radial upsetting pressure of 12MPa, maintains pressure, and completes the welding process.

[0047] S06, post-weld processing: first loosen the radial pressurizing fixture, move the slide backward, then loosen the rotary clamping fixture, and remove the welded parts of the titanium alloy and the aluminum alloy; finally, use machining to remove the excess aluminum alloy welding flash.

[0048] The bonding strength between the brazing material layer and the titanium alloy substrate before welding in Examples 1, 2, and 3, as well as the shear strength of the weld joint between the titanium alloy and the aluminum alloy after welding were tested respectively; at the same time, the shear strength of the weld joint between the titanium alloy and the aluminum alloy after welding in Comparative Example 1 was tested, and the test results are shown in Table 1 below.

[0049] Table 1:

[0050] Embodiment 4: A friction welding method for dissimilar metals with a large melting point difference, wherein when the titanium alloy weldment 10 is hot-dip plated in the above-mentioned embodiment 1, embodiment 2 or embodiment 3, the following is adopted: Figure 3The device shown comprises a heatable solder groove 11 and a sealing cover 12, and the heatable solder groove 11 and the sealing cover 12 can be sealed and connected; wherein, the inner groove bottom of the heatable solder groove 11 is rotatably connected to the first rotating support 110, and the bottom surface of the sealing cover 12 is provided with a second rotating support 121 corresponding to the first rotating support 110, and the second rotating support 121 is connected with a rotating shaft 122, and the rotating shaft 122 passes through the sealing cover 12; the first rotating support 110 and the second rotating support 121 are provided with corresponding slots.

[0051] When in use, first, the lower end of the titanium alloy weldment 10 to be processed is fixedly clamped in the slot of the first rotating support 110 (this can be achieved by providing a spring-type clamping device in the slot), and then the sealing cover 12 is closed so that the upper end of the titanium alloy weldment 10 is fixedly clamped in the slot of the second rotating support 121 (this can be achieved by providing a spring-type clamping device in the slot), and then the contact part between the sealing cover 12 and the heatable solder tank 11 is sealed; high-temperature solder liquid is introduced into the heatable solder tank 11 and is kept warm by the heating device in the heatable solder tank 11, and at the same time, the second rotating support 121 is rotated by rotating the rotating shaft 122, driving the titanium alloy weldment 10 to rotate, thereby realizing the "self-rotation" hot-dip solder plating of the titanium alloy weldment 10.

[0052] The hot dip plating device in Example 4 of the present application is only a specific embodiment, and its purpose is to enable technical personnel in this field to understand the scheme of the present application more intuitively and clearly; the hot dip plating device of the present application is not limited to the description in Example 4 of the present application, as long as the device can perform hot dip plating of high-temperature solder during the rotation of the titanium alloy weldment 10 around its own axis, it can be protected within the scope of the present application.

Claims

1. A friction welding method for dissimilar metals with a large melting point difference, characterized in that: The specific steps include: S01. Processing of weldments of titanium alloy components and aluminum alloy components; S02. Preparation of hot-dip brazing layer on the surface of titanium alloy weldments and pretreatment of aluminum alloy weldments; S03. Processing of rotary clamping fixtures and radial pressurizing fixtures according to the sizes of titanium alloy weldments and aluminum alloy weldments coated with brazing layer on the surface; S04. Installing the rotary clamping fixture on the main shaft of the friction welding machine, installing the radial pressurizing fixture on the moving slide of the friction welding machine, and using the rotary clamping fixture and radial pressurizing fixture to pre-clamp the titanium alloy weldments and aluminum alloy weldments coated with brazing layer on the surface respectively; S05. Setting welding parameters on the control interface of the friction welding machine, starting the friction welding machine, and completing the friction welding process of friction, upsetting and pressure holding of weldments; S06. Post-weld processing; When hot-dip plating is performed on titanium alloy weldments, a device including a heatable solder tank and a sealing cover is used, and the heatable solder tank and the sealing cover can be sealed and connected; wherein, the inner bottom of the heatable solder tank is rotatably connected to a first rotating support, a second rotating support is arranged on the bottom surface of the sealing cover corresponding to the first rotating support, and a rotating shaft is connected to the second rotating support, and the rotating shaft passes through the sealing cover; corresponding slots are arranged on the first rotating support and the second rotating support.

2. The friction welding method of dissimilar metals with large melting point difference according to claim 1, characterized in that: The titanium alloy component is a rod-shaped or tubular component, and the aluminum alloy component is a ring-shaped component.

3. A friction welding method for dissimilar metals with a large melting point difference according to claim 1 or 2, characterized in that: The specific dimensions of the weldment processing in step S01 are as follows: the titanium alloy component is processed into a weldment with an outer diameter D of Φ20mm to Φ160mm and a length L of 50mm to 300mm; the aluminum alloy component is processed into a weldment with an inner diameter d of D+ (1 to 2) mm, a wall thickness t of 8mm to 20mm, and a width w of 3mm to 30mm.

4. The friction welding method for dissimilar metals with a large melting point difference according to claim 3, characterized in that: The specific steps of preparing the brazing material layer on the surface of the titanium alloy weldment in step S02 are: S21. The surface of the titanium alloy weldment is polished with sandpaper to remove the oxide film and burrs on the surface of the titanium alloy, and the surface of the titanium alloy weldment is degreased after polishing; S22. After performing step S21, the titanium alloy weldment is immersed in an activation solution at 50-60°C and kept warm for 20-25 minutes to complete the activation treatment; S23. After the activation treatment, the titanium alloy weldment is vertically immersed in a solder liquid at 730-800°C and kept warm for 5-10 minutes, and the titanium alloy weldment is kept rotating around its own axis to complete the hot-dip solder treatment; S24. The hot-dip-plated titanium alloy weldment is placed in a heat treatment furnace and kept warm at 800-1000°C for 3-6 hours to complete the thermal diffusion treatment, and finally a titanium alloy weldment with a surface uniformly coated with a solder layer is obtained.

5. The friction welding method of dissimilar metals with large melting point difference according to claim 4, characterized in that: The activation liquid is a chromium-fluorine activation liquid, and its formula is CrO3: 35-45g / L, 40% HF solution: 20-30ml / L; the solder liquid adopts Al-10Si-0.1Re multi-alloy solder; the rotation speed of the titanium alloy weldment around its own axis is 50-200r / min.

6. The friction welding method for dissimilar metals with a large melting point difference according to claim 1, characterized in that: The pre-treatment of the aluminum alloy weldment in step S02 includes removing oxide film, burrs and oil from the aluminum alloy weldment.

7. The friction welding method for dissimilar metals with a large melting point difference according to claim 1, characterized in that: The welding parameters of the friction welding machine in step S05 are: friction speed 900r / min-2300r / min, friction pressure 2MPa-5MPa, upsetting speed 400r / min-1000r / min, upsetting pressure 5MPa-12MPa.

8. The friction welding method for dissimilar metals with a large melting point difference according to claim 1, characterized in that: The specific steps of the post-weld processing in step S06 are: first, loosen the radial pressurizing fixture, move the slide backward, then loosen the rotary clamping fixture, and remove the welded parts of the titanium alloy and the aluminum alloy; then use machining to remove excess aluminum alloy welding flash and coating.

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