A composite welding method of titanium-aluminum composite plate

Abstract

The present application relates to the technical field of composite welding, and discloses a composite welding method for titanium-aluminum composite plates, in which two titanium-aluminum composite plates to be welded are arranged in butt joint, cold metal transfer welding technology is used to weld the titanium side base plate, and friction stir welding technology is used to weld the aluminum side base plate, wherein, in the welding process, cold metal transfer arc is used as a heat source and the stirring head of the friction stir welding machine is used to generate heat respectively. The present application uses cold metal transfer welding and friction stir welding to perform butt joint welding on the titanium-aluminum composite plate, and the welding process is stable, the shape is good, and the quality is high. While performing butt joint welding on the titanium-aluminum composite plate, the intermetallic compound generated when welding the titanium side can be broken by the stirring action of the stirring head of the friction stir welding, so as to effectively improve the interface bonding strength of the butt joint welding of the composite plate.

Description

Technical Field

[0001] The present invention relates to the technical field of composite welding, in particular to a composite welding method for titanium-aluminum composite plates. Background Art

[0002] With the continuous development of metal material technology, composite plates made of titanium and aluminum as parent materials have become one of the important directions for the development of lightweight metal composite plates. Titanium and titanium alloys, as a new material with excellent comprehensive performance, are widely used in fields such as aerospace. In actual production, bimetallic composite plates with relatively simple composite processes such as titanium / steel, titanium / copper, copper / aluminum, and copper / steel have been widely used. However, for bimetallic layered composite plates with large performance differences such as titanium / aluminum, their research and application still need further development due to the influence of process control requirements.

[0003] In principle, the preparation methods for titanium / aluminum composite plates can be categorized into two main types: solid-state composite and solid-liquid composite. These primarily include explosive composite, rolling composite, and solid-liquid casting and rolling. The explosive composite method uses explosives to drive the composite plate into an oblique collision with the base plate, generating a metal jet that removes the oxide film on the metal surface while simultaneously achieving metallurgical bonding under immense pressure. Solid-liquid casting and rolling is a new technology currently used to prepare titanium / aluminum composite plates. Liquid metal rapidly cools on rotating rollers while undergoing plastic deformation under the action of the rolling force, resulting in a composite plate with high bonding strength. The rolling composite method involves polishing and cleaning the metal surface before plastically deforming it using rolling. This simultaneously breaks down the surface oxide film, exposing fresh metal, and achieving bonding under the pressure of the rolling mill. All of these methods produce intermetallic compounds at the titanium / aluminum interface. Some intermetallic compounds increase the interface strength, while excessive intermetallic compounds can compromise the bonding strength of the transition layer.

[0004] At present, the research on the titanium-aluminum composite plate mainly focuses on the manufacturing processes of explosive welding and thermomechanical rolling. There is less research on the butt welding of titanium-aluminum composite plates and less experimental research on the butt welding of titanium-aluminum composite plates. The butt welding interface bonding strength of titanium-aluminum composite plates is poor, and excessive intermetallic compounds are formed during the welding process, which affects the preparation quality of titanium-aluminum composite plates. Summary of the Invention

[0005] The purpose of the present invention is to provide a composite welding method for titanium-aluminum composite plates, which combines cold metal transfer welding technology with stir friction welding technology to reduce the intermetallic compounds formed during the welding process and improve the bonding strength of the titanium-aluminum composite plate butt interface.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A composite welding method for titanium-aluminum composite plates is characterized by comprising the following steps: pre-treating the welding surfaces of two titanium-aluminum composite plates to be welded and then butting them together so that the titanium side substrates and the aluminum side substrates of the two titanium-aluminum composite plates are located on the same side and the aluminum side substrates are located on the same side, using cold metal transfer welding technology to weld the titanium side substrates, and using stir friction welding technology to weld the aluminum side substrates, wherein during the welding process, a cold metal transfer arc is used as a heat source and the stirring head of the stir friction welding machine is rotated to generate heat.

[0008] Furthermore, the specific process of welding the titanium side substrate using cold metal transfer welding technology is as follows: the cold metal transfer arc welding gun is located above the titanium side substrate, a shielding gas nozzle is provided outside the cold metal transfer arc welding gun, the arc of cold metal transfer welding is used as the heat source, and the welding wire is sent out by the cold metal transfer arc welding gun as the melting electrode; the shielding gas nozzle is pre-flowed with shielding gas for 3.0-5.0s, the arc starting position is selected on the titanium side of the composite plate, and the cold metal transfer arc is started to weld according to the weld layout; after welding is completed, the cold metal transfer arc is turned off, the shielding gas nozzle continues to supply shielding gas for 3.0-5.0s, and then the welding gun is raised by 0.5-2.0mm.

[0009] Furthermore, the included angle between the central axis of the cold metal transfer arc welding gun and the surface of the titanium side substrate is 60-90°.

[0010] Furthermore, the welding wire used in the cold metal transfer welding is a titanium alloy welding wire with a diameter of 1.0 mm to 2.0 mm.

[0011] Furthermore, the welding current of cold metal transfer welding is 180-240A, the arc voltage is 25-27V, the wire feeding speed of the cold metal transfer arc welding gun is 2.5-6m / min, and the welding speed of the cold metal transfer arc welding gun is 1.0-2.0m / min.

[0012] Furthermore, the protective gas flow rate of the protective gas nozzle is 15-25 L / min; the protective gas is pure argon, pure helium or a mixture of the two.

[0013] Furthermore, the specific process of welding the aluminum side substrate using stir friction welding technology is: install the welding tool on the main shaft of the stir friction welding machine, start the stir friction welding machine, move the welding tool to the starting position of the aluminum side substrate docking and move the main shaft downward, the welding tool shoulder penetrates into the surface of the aluminum side substrate to a certain depth, and uses the stirring head of the stir friction welding machine to rotate and generate heat to weld the aluminum side substrate. After welding is completed, the welding tool is pulled out from the welding end position.

[0014] Furthermore, the welding tool shoulder penetrates into the surface of the aluminum side substrate by 0.2-0.4 mm, stays for 2.0s-5.0s, and then moves at a welding speed of 80-140 mm / min;

[0015] During the welding process, the rotation speed of the friction stir welding tool is 1000-1200 r / min, the downward pressure is 0.2 mm, and the inclination angle is 2°.

[0016] Furthermore, the titanium-aluminum composite plate is a TC1-1060-6061 titanium-aluminum composite plate.

[0017] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0018] The composite welding method for titanium-aluminum composite plates provided by the present invention uses cold metal transition welding technology to weld the titanium side substrate, and stir friction welding technology to weld the aluminum side substrate. While butt-welding the titanium-aluminum composite plates, the stirring effect of the stir friction welding technology can be used to refine and disperse the intermetallic compounds generated when welding the titanium side, effectively improving the interface bonding strength of the composite plate butt welding. The present invention uses cold metal transition welding and stir friction welding composite welding to butt-weld the titanium-aluminum composite plates. The welding process is stable, the forming is good, and the quality is high. This composite welding technology combines the advantages of both in improving weld strength, toughness, and corrosion resistance. While ensuring high-quality welding, it can also achieve energy conservation and emission reduction, reduce costs, and is particularly suitable for high-end manufacturing applications with strict requirements on welding quality and high requirements on thermal deformation control. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a schematic diagram of cold metal transfer welding of the titanium side substrate of the present invention;

[0021] Figure 2 This is a schematic diagram of friction stir welding of the aluminum side substrate of the present invention;

[0022] Figure 3 This is a photo of the cold metal transfer welding effect of the titanium side substrate in an embodiment of the present invention;

[0023] Figure 4 This is a photo of the friction stir welding effect of the aluminum side substrate in an embodiment of the present invention;

[0024] Figure 5 (a) and (b) are the metallographic images of the titanium-aluminum composite plate base material and the weld, respectively.

[0025] Figure 6(b) shows the hardness distribution at the weld of the titanium-aluminum composite plate tested in the direction shown in (a).

[0026] Explanation of the accompanying symbols: 1 is a CMT welding gun; 2 is a welding wire; 3 is a titanium side weld; 4 is a titanium side substrate; 5 is an aluminum side substrate; 6 is an aluminum side weld; 7 is a friction stir welding head. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0028] The purpose of the present invention is to provide a composite welding method for titanium-aluminum composite plates, wherein the titanium side substrate is welded by cold metal transfer welding technology; the aluminum side substrate is welded by a composite welding process of stir friction welding. Since stir friction welding can stir and crush the intermetallic compounds generated at the interface during the cold metal transfer welding process, the bonding strength of the titanium-aluminum composite plate butt interface is improved.

[0029] Cold Metal Transfer (CMT) is a new welding process that uses mechanical wire retraction to force the molten droplet away from the wire. This allows for droplet transfer at very low or no current, reducing the temperature of the molten pool and droplet. It offers advantages such as low heat input, stable droplet transfer, no spatter, and minimal deformation. This low heat input effectively reduces the impact of heat input on the aluminum side when welding the titanium side. CMT welding on the titanium side produces intermetallic compounds such as Ti3Al, TiAl, and TiAl3 in the transition layer of the titanium-aluminum composite plate.

[0030] Friction stir welding (FSW) has the outstanding advantages of good weld formation, excellent mechanical properties, low energy loss in the welding process, green environmental protection and high welding efficiency. It has the characteristics of low heat input and no metallurgical reaction during welding. When welding the aluminum side of titanium-aluminum composite plates, it can reduce or avoid welding defects such as element burnout, cracks, and pores. The stirring action of stir friction welding during the welding process can effectively refine the intermetallic compounds produced in the transition layer of the titanium-aluminum composite plate and improve the bonding strength of the interface.

[0031] In order to overcome the problem of poor interface bonding strength in welding titanium-aluminum composite plates, the present invention combines stir friction welding and CMT to improve the interface bonding strength during the welding process.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] The composite welding method of titanium-aluminum composite plates provided by the present invention comprises the following steps:

[0034] The two titanium-aluminum composite plates to be welded are butt-jointed, and the titanium side substrate is welded using cold metal transfer welding technology, and the aluminum side substrate is welded using stir friction welding technology. During the welding process, a cold metal transfer arc is used as a heat source, and the stirring head of the stir friction welding machine rotates to generate heat. Specifically, it includes:

[0035] Step 1: pre-treat the surfaces of the two titanium-aluminum composite plates to be welded, and fix the two titanium-aluminum composite plates on a welding workbench by butting them together, wherein the butting is performed so that the titanium side substrates are on the same side and the aluminum side substrates are on the same side;

[0036] Step 2: Using a cold metal transfer arc as a heat source and a welding wire as a melting electrode to be fed from a cold metal transfer arc welding gun, the titanium side substrate is welded using cold metal transfer technology;

[0037] Step 3: Install the welding tool on the main shaft of the friction stir welding machine, start the friction stir welding machine, move the welding tool to the starting position of the aluminum side substrate docking and move the main shaft downward. The welding tool shoulder penetrates the surface of the aluminum side substrate to a certain depth. The stirring head of the friction stir welding machine rotates to generate heat to weld the aluminum side substrate;

[0038] Step 4: After the welding is completed, the welding tool is pulled out from the welding end position to obtain a butt-jointed composite plate weldment formed by friction stir welding of the aluminum side and cold metal transfer welding of the titanium side. Example

[0039] In the embodiment of the present invention, a TC1-6061 titanium-aluminum composite plate with a size of 110 mm × 80 mm × 10 mm is used as the welded part. The thickness of the titanium side substrate is 3 mm, and the thickness of the aluminum side substrate is 7 mm. The titanium side substrate is welded by CMT welding, and the aluminum side substrate is welded by stir friction welding.

[0040] The platform and tools used for CMT welding of the titanium side are: ABB welding robot and rotary control platform; the shielding gas is: high-purity argon; the welding power supply is: Fronius TPS4000 welding power supply; the CMT welding process parameters are: titanium alloy welding wire with a diameter of 1.2mm, welding current of 220A, welding voltage of 26.7V, and shielding gas flow of 16L / min.

[0041] The friction stir welding head used for the aluminum side friction stir welding is: CT-6.6-18 welding head; the friction stir welding process parameters are: rotation speed of 1000r / min, welding speed of 120mm / min, downward pressure of 0.2mm, and inclination angle of 2°.

[0042] The composite welding method of the titanium-aluminum composite plate of this embodiment specifically includes the following steps:

[0043] (1) Use cold metal transfer welding technology to weld the titanium side

[0044] Place the titanium-aluminum composite plate component to be welded on a CMT welding workbench. Position the cold metal transfer arc welding gun above the titanium side base plate 4 of the titanium-aluminum composite plate. A shielding gas nozzle is attached to the cold metal transfer arc welding gun. Secure the CMT welding gun 1 and shielding gas nozzle at an angle of 60-90° to the horizontal. Use titanium alloy welding wire. Pre-flow argon shielding gas into the shielding gas nozzle for 5.0 seconds. Select the arc starting position. Use the cold metal transfer arc as the heat source and the welding wire 2 as the melting electrode to be fed from the cold metal transfer arc welding gun. Figure 1 The welding current for cold metal transfer welding is 180-240A, the arc voltage is 25-27V, the wire feed speed of the cold metal transfer arc welding gun is 2.5-6m / min, and the welding speed of the cold metal transfer arc welding gun is 1.0-2.0m / min. After welding the titanium side baseplate, the cold metal transfer arc is turned off, and the shielding gas nozzle continues to supply shielding gas for 3.0-5.0 seconds. Then, the welding gun is raised 0.5-2.0mm.

[0045] (2) Friction stir welding of the aluminum side

[0046] Install the friction stir welding head 7 on the main shaft of the friction stir welding machine, start the friction stir welding machine, move the friction stir welding head 7 to the starting position of the composite plate aluminum side substrate 5 and move the main shaft downward so that the friction stir welding head 7 penetrates 0.2mm into the surface of the workpiece to be welded, stays for 2.0s-5.0s, and then moves at a welding speed of 80-140mm / min. Figure 2 After the welding is completed, the welding tool is pulled out from the welding end position to obtain a butt-jointed composite plate weldment with the aluminum side welded by friction stir welding and the titanium side welded by cold metal transfer welding. Among them, the cold metal transfer welding effect of the titanium side substrate is as shown in the figure. Figure 3 As shown, the friction stir welding effect on the aluminum side is as follows Figure 4 shown.

[0047] (3) After welding, stress relief treatment should be carried out by hammering.

[0048] Comparison of the metallographic structure of the weld and the base material after welding of titanium-aluminum composite plate Figure 5 As shown, (a) shows the metallographic structure of the parent material, and (b) shows the metallographic structure of the weld. The titanium-aluminum composite plate to be welded in this example is a composite of a TC1 titanium alloy plate and a 6061 aluminum alloy plate, welded together using explosive welding. The metallographic structure of the weld obtained through the welding process in this example, shown in Figure (b), is significantly smaller than that in Figure (a). This is due to the friction stir welding process, where the friction stir heating and crushing action of the friction stir welding horn achieve a refined and dispersed titanium-aluminum intermetallic compound.

[0049] Intermetallic compounds can cause stress concentration and reduce the mechanical properties of the workpiece. Stir friction welding can refine and disperse the intermetallic compounds, thereby reducing stress concentration and improving the mechanical properties of the weld. Figure 6 As shown in the figure, the hardness of the weld corresponds to 7mm-20mm, and the hardness of the base material corresponds to 1mm-6mm and 21mm-30mm. It can be clearly seen that the hardness of the titanium side and the aluminum side after welding is higher than that of the base material.

[0050] The present invention proposes a composite welding method for titanium-aluminum composite plates, employing cold metal transfer welding for the titanium side of the composite plate and friction stir welding for the aluminum side. This hybrid cold metal transfer welding and friction stir welding method, employed in the present invention, achieves a stable butt-welding process, excellent forming, and high quality. While the titanium-aluminum composite plates are being butt-welded, the stirring and heating action of the friction stir welding head refines and disperses the intermetallic compounds produced during welding on the titanium side, effectively improving the interfacial bonding strength of the composite plate butt weld.

[0051] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

[0052] The embodiments described are preferred implementations of the present invention, but the present invention is not limited to the above implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the scope of protection of the present invention.

Claims

1. A composite welding method for titanium-aluminum composite plates, characterized in that: The method comprises the following steps: pre-treating the welding surfaces of two titanium-aluminum composite plates to be welded and then butting them together so that the titanium side substrates and the aluminum side substrates of the two titanium-aluminum composite plates are located on the same side, welding the titanium side substrates using a cold metal transfer welding technique, and welding the aluminum side substrates using a stir friction welding technique, wherein during the welding process, a cold metal transfer arc is used as a heat source, and a stir head of the stir friction welding machine is used to rotate to generate heat; The welding current of the cold metal transfer welding is 180-240A, the arc voltage is 25-27V, the wire feeding speed of the cold metal transfer arc welding gun is 2.5-6m / min, and the welding speed of the cold metal transfer arc welding gun is 1.0-2.0m / min; During the friction stir welding process, the welding tool shoulder penetrates into the surface of the aluminum side substrate by 0.2-0.4mm, stays for 2.0s-5.0s, and then moves at a welding speed of 80-140mm / min; the rotation speed of the friction stir welding tool is 1000-1200r / min, the downward pressure is 0.2mm, and the inclination angle is 2°.

2. The composite welding method of titanium aluminum composite plate according to claim 1, characterized in that: The specific process of welding the titanium side substrate using cold metal transfer welding technology is as follows: the cold metal transfer arc welding gun is located above the titanium side substrate, and a shielding gas nozzle is provided outside the cold metal transfer arc welding gun. The arc of cold metal transfer welding is used as the heat source, and the welding wire is sent out by the cold metal transfer arc welding gun as the melting electrode; the shielding gas nozzle is pre-filled with shielding gas for 3.0-5.0s, the arc starting position is selected on the titanium side of the composite plate, and the cold metal transfer arc is started to weld according to the weld layout; after welding is completed, the cold metal transfer arc is turned off, and the shielding gas nozzle continues to supply shielding gas for 3.0-5.0s, and then the welding gun is raised by 0.5-2.0mm.

3. The composite welding method of titanium aluminum composite plate according to claim 2, characterized in that: The included angle between the central axis of the cold metal transfer arc welding gun and the surface of the titanium side substrate is 60-90 degrees.

4. The composite welding method of titanium aluminum composite plate according to claim 2, characterized in that: The welding wire used in cold metal transfer welding is titanium alloy welding wire with a diameter of 1.0mm-2.0mm.

5. The composite welding method of titanium aluminum composite plate according to claim 2, characterized in that: The welding current of cold metal transfer welding is 220A, the arc voltage is 26.7V, and the titanium alloy welding wire uses a diameter of 1.2mm.

6. The composite welding method of titanium aluminum composite plate according to claim 2, characterized in that: The protective gas flow rate of the protective gas nozzle is 15-25 L / min; the protective gas is pure argon, pure helium or a mixture of the two.

7. The composite welding method of titanium aluminum composite plate according to claim 2, characterized in that: The specific process of welding the aluminum side substrate using stir friction welding technology is as follows: install the welding tool on the main shaft of the stir friction welding machine, start the stir friction welding machine, move the welding tool to the starting position of the aluminum side substrate docking and move the main shaft downward, the welding tool shoulder penetrates the surface of the aluminum side substrate to a certain depth, and uses the stirring head of the stir friction welding machine to rotate and generate heat to weld the aluminum side substrate. After welding is completed, the welding tool is pulled out from the welding end position.

8. The composite welding method of titanium aluminum composite plate according to claim 7, characterized in that: During the friction stir welding process, the welding speed is 120 mm / min.

9. The composite welding method of titanium aluminum composite plate according to claim 7, characterized in that: During the friction stir welding process, the rotation speed of the friction stir welding tool is 1000 r / min.

10. The composite welding method of titanium aluminum composite plate according to any one of claims 1 to 9, characterized in that: The titanium-aluminum composite plate is a TC1-6061 titanium-aluminum composite plate.

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