A preheating method for rotary friction welding of TC4 titanium alloy / GH4169 high-temperature alloy dissimilar metals

Abstract

This invention discloses a preheating method for rotary friction welding of dissimilar metals, specifically TC4 titanium alloy and GH4169 high-temperature alloy, belonging to the field of friction welding technology. The method involves preheating the GH4169 high-temperature alloy to 970-990℃ and holding it at that temperature for 5-10 minutes before friction welding it with the TC4 titanium alloy. During friction welding, the preheated GH4169 high-temperature alloy is placed at the feed end of the friction welding machine, while the TC4 titanium alloy serves as the rotating end. This invention softens the high-hardness GH4169 by preheating it to 980±10℃ before welding, thereby solving the "plastic deformation mismatch" problem at the welding interface and significantly improving the welding strength.

Description

Technical Field

[0001] This invention relates to the field of friction welding technology, and specifically to a method for preheating TC4 titanium alloy / GH4169 high-temperature alloy dissimilar metal rotary friction welding. Background Technology

[0002] In recent years, dissimilar material joining technology has gradually become one of the most critical and challenging technologies in the welding field. It can not only effectively reduce structural weight and energy consumption but also fully utilize the advantages of different materials, thus providing appropriate functionality for specific applications. Titanium alloys, represented by TC4, and high-temperature alloys, represented by GH4169, are widely used in aerospace, medical equipment, automotive manufacturing, and energy industries due to their good high-temperature performance, low density, and excellent corrosion resistance. However, welding these two materials is extremely difficult, severely restricting the widespread application of titanium alloy / high-temperature alloy composite structures.

[0003] The poor weldability of the two is mainly reflected in the following aspects: (1) The physical properties of TC4 titanium alloy and GH4169 high-temperature alloy are very different: including density, melting point, coefficient of thermal expansion, etc., which will make it difficult for the welding interface to fuse during the welding process; (2) The two have the characteristics of chemical reaction: nickel and titanium can undergo chemical reaction at the welding temperature to generate a variety of brittle and hard intermetallic compounds, which will significantly reduce the mechanical properties of the joint. Therefore, the weldability of titanium alloy / high-temperature alloy is very poor, and the welding of the two has long been an engineering problem.

[0004] Existing welding technologies for dissimilar materials like TC4 titanium alloy and GH4169 high-temperature alloy mainly include brazing, diffusion welding, and friction welding. Brazing relies on the high-temperature melting of a filler metal, which spreads and wets the joint of the base materials, eventually forming a unified joint. However, brazing of TC4 titanium alloy / GH4169 high-temperature alloy generally suffers from low joint strength. This is due to the relatively low strength of the filler metal itself, which is inferior to that of titanium alloys and high-temperature alloys. More importantly, the high-temperature brazing process inevitably leads to the formation of brittle intermetallic compounds. For diffusion welding, element diffusion at high temperatures still results in the formation of a brittle and hard intermetallic compound layer at the interface, resulting in low weld strength (less than 200 MPa) and limited application value. Adding an intermediate layer can improve this, but this leads to high costs and low efficiency. For friction welding, due to the significant difference in high-temperature strength between the two metals, "plastic deformation mismatch" occurs during welding, manifesting as long cracks along the interface and incomplete fusion in the weld joint, significantly affecting the joint's mechanical properties.

[0005] Currently, welding of titanium alloys / high-temperature alloys mainly involves brazing and diffusion welding or friction welding with an intermediate layer. However, these methods offer limited improvement in joint performance, and the addition of an intermediate layer increases joint instability, while also being complex and costly. Therefore, there is a need to develop a low-cost, simple welding process for welding TC4 titanium alloy and GH4169 high-temperature alloy. Summary of the Invention

[0006] To address the shortcomings of the aforementioned background technology, this invention primarily solves the problem of "plastic deformation mismatch" in the friction welding process. This invention provides a preheating method for rotary friction welding of dissimilar metals, specifically TC4 titanium alloy and GH4169 high-temperature alloy. This method preheats the GH4169 high-temperature alloy to 980±10℃ before welding, softening the high-hardness GH4169 and thus resolving the "plastic deformation mismatch" problem at the welding interface, significantly improving the welding strength of the two metals.

[0007] The present invention aims to provide a method for preheating TC4 titanium alloy / GH4169 high-temperature alloy dissimilar metal rotary friction welding, comprising the following steps:

[0008] The GH4169 high-temperature alloy is preheated at 970~990℃ and held for 5~10 minutes before being friction-welded with TC4 titanium alloy. During friction welding, the preheated GH4169 high-temperature alloy is placed at the feed end of the friction welding machine, and the TC4 titanium alloy is used as the rotating end.

[0009] Preferably, during friction welding, the rotation speed is set to ≤600 rpm, the welding pressure to ≥300 MPa, and the upsetting pressure to ≥300 MPa.

[0010] Preferably, during friction welding, a welding method with axial shortening control is used, and the axial shortening of the weld is controlled to be 5mm.

[0011] Preferably, the heating rate during preheating is 5~10℃ / min.

[0012] Preferably, during the preheating process, the preheating temperature is monitored using a thermocouple or an infrared thermometer; when induction heating is used for preheating, a thermocouple or an infrared thermometer is used for temperature monitoring; when a muffle furnace is used for preheating, a thermocouple is used for temperature monitoring.

[0013] Preferably, when using a thermocouple for temperature monitoring, the thermocouple measuring end should be in close contact with the workpiece surface; when using an infrared thermometer for temperature monitoring, the infrared emissivity of the material should be calibrated to avoid inaccurate temperature measurement.

[0014] Preferably, a muffle furnace or induction heating is used for preheating.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] This invention provides a preheating method for rotary friction welding of dissimilar metals, TC4 titanium alloy and GH4169 high-temperature alloy. By preheating the GH4169 high-temperature alloy before welding, the high-temperature hardness of GH4169 is softened, thereby solving the problem of "plastic deformation mismatch" at the interface during the welding process. This method can significantly improve the welding strength of the two metals and has the advantages of simple process and low cost, making it suitable for industrial mass production.

[0017] This invention enables low-cost and high-efficiency welding of dissimilar metals such as the difficult-to-weld TC4 titanium alloy / GH4169 high-temperature alloy, and can achieve industrial-scale mass production.

[0018] The method provided by this invention produces joints with high welding strength: compared with traditional brazing, diffusion welding without an intermediate layer, and direct friction welding (the weld joint strength is less than 200 MPa), the weld joint strength of this preheating method can reach more than 500 MPa. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a friction welding machine;

[0020] Figure 2 The friction welding sample is preheated.

[0021] Figure 3 The cross-sectional morphology of the joint;

[0022] Figure 4 The tensile test curve of the joint is shown. Detailed Implementation

[0023] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0024] This invention leverages the inherent advantages of friction welding—high welding efficiency and low cost—making it suitable for large-scale automated industrial production. Solving the "plastic deformation mismatch" problem during friction welding will significantly expand the application range of TC4 titanium alloy / GH4169 high-temperature alloy. This invention provides a preheating method for rotary friction welding of dissimilar metals, specifically TC4 titanium alloy / GH4169 high-temperature alloy. By preheating the GH4169 high-temperature alloy before welding, the high-hardness GH4169 softens, thus solving the "plastic deformation mismatch" problem at the welding interface. This significantly improves the welding strength of both materials and offers the advantages of simple process and low cost, making it suitable for industrial mass production.

[0025] To achieve the above objectives, the present invention provides a preheating method for rotary friction welding of TC4 titanium alloy / GH4169 high-temperature alloy dissimilar metals, comprising the following steps:

[0026] The GH4169 high-temperature alloy is preheated at 970~990℃ and held for 5~10 minutes before being friction-welded with TC4 titanium alloy. During friction welding, the preheated GH4169 high-temperature alloy is placed at the feed end of the friction welding machine, and the TC4 titanium alloy is used as the rotating end.

[0027] This invention solves the problem of "plastic deformation mismatch" at the interface during welding by preheating the GH4169 high-temperature alloy before welding, thereby significantly improving the welding strength of the two.

[0028] During friction welding, the rotation speed is set to ≤600 rpm, the welding pressure to ≥300 MPa, and the upsetting pressure to ≥300 MPa. A welding method controlling axial shortening is used during friction welding, with the axial shortening controlled at 5 mm.

[0029] The preheating rate is 5~10℃ / min. A muffle furnace or induction heating method is used for preheating.

[0030] During the preheating process, the preheating temperature is monitored using thermocouples or infrared thermometers; when induction heating is used for preheating, thermocouples or infrared thermometers are used for temperature monitoring; when a muffle furnace is used for preheating, thermocouples are used for temperature monitoring.

[0031] When using thermocouples for temperature monitoring, the thermocouple measuring tip should be in close contact with the workpiece surface; when using infrared thermometers for temperature monitoring, the infrared emissivity of the material should be calibrated to avoid inaccurate temperature measurement.

[0032] An exemplary method for preheating TC4 titanium alloy / GH4169 high-temperature alloy dissimilar metal rotary friction welding includes:

[0033] Step 1) Before welding, preheat the GH4169 high-temperature alloy using a muffle furnace or induction heating.

[0034] For preheating, a muffle furnace or similar tool can be used to preheat the entire GH4169 high-temperature alloy component; alternatively, induction heating can be used to locally preheat the joint area of ​​the GH4169 to be welded. When using a muffle furnace for preheating, a heating rate of 5–10 °C / min is recommended to ensure thorough heating of the workpiece. When using induction heating for preheating, a faster heating rate can be used.

[0035] Step 2) Monitor the preheating temperature in real time using thermocouples or infrared temperature measuring devices.

[0036] During the preheating process, the preheating temperature should be monitored using a thermocouple or an infrared thermometer. When induction heating is used to heat the workpiece, it is recommended to use a thermocouple or infrared thermometer for temperature monitoring; when a muffle furnace is used to heat the workpiece, it is recommended to use a thermocouple for temperature monitoring. When using a thermocouple for temperature monitoring, the thermocouple measuring tip should be in close contact with the workpiece surface; when using an infrared thermometer for temperature monitoring, it is important to calibrate the infrared emissivity of the material to avoid inaccurate temperature measurements.

[0037] Step 3) When the preheating temperature reaches 980±10℃, stop heating and hold for 5 to 10 minutes before friction welding.

[0038] The temperature of 980±10℃ was chosen because it is the commonly used solution treatment temperature for GH4169. Preheating at this temperature before welding is equivalent to performing a solution heat treatment on the material, which will not cause performance degradation. When the workpiece reaches 980±10℃, welding should not be carried out immediately. It should be held at this temperature for 5 minutes to ensure uniform temperature and thorough heating of the workpiece.

[0039] Step 4) Select welding parameters with high friction pressure and low rotation speed to complete the entire welding process.

[0040] For friction welding after preheating, a low-speed (low friction linear velocity) and high-pressure welding process should be selected. For example, the speed should be ≤600 rpm, the welding pressure ≥300 MPa, and the upsetting pressure ≥300 MPa. Welding methods that control axial shortening should be preferred, with the axial shortening controlled at 5 mm.

[0041] GH4169 high-temperature alloy is selected for the feed end of the friction welding machine, and TC4 titanium alloy is used for the rotating end. Friction welding should be performed quickly after the preheated material is removed from the muffle furnace to prevent a significant drop in interface temperature.

[0042] GH4169 is used as the feed end because, on the one hand, it is difficult to place GH4169 at the feed end when it is in a red-hot state (980℃), and on the other hand, GH4169 at the rotating end will cause faster heat loss and lower the sample temperature. The rapid increase in the thermal intensity of GH4169 will significantly reduce the preheating effect.

[0043] It should be noted that, unless otherwise specified, the experimental methods used in this invention are all conventional methods; and the reagents and materials used, unless otherwise specified, are all commercially available.

[0044] Example 1

[0045] A preheating method for rotary friction welding of TC4 titanium alloy / GH4169 high-temperature alloy dissimilar metals includes the following steps:

[0046] Step 1) Before welding, preheat the GH4169 high-temperature alloy using a muffle furnace or induction heating.

[0047] TC4 titanium alloy and GH4169 high-temperature alloy bars with a diameter of 25 mm and a length of 100 mm were selected as the base materials for welding. Before welding, the surfaces to be welded were machined on a lathe to ensure surface flatness and roughness. Alcohol was used to wipe the surfaces to remove oil and dirt.

[0048] Based on the conditions of this laboratory, a muffle furnace was used for overall preheating of the GH4169 high-temperature alloy before welding. To ensure that the workpiece to be welded is thoroughly heated, a heating rate of 10℃ / min was selected.

[0049] Step 2) Monitor the preheating temperature in real time using thermocouples or infrared temperature measuring devices.

[0050] During the preheating process, the preheating temperature is monitored using a thermocouple, and the thermocouple measuring end must be in close contact with the surface of the GH4169 high-temperature alloy rod.

[0051] Step 3) When the preheating temperature reaches 980℃, stop heating and hold for 5 minutes before friction welding. Specifically, when the heated GH4169 high-temperature alloy reaches 980℃, stop heating and hold for 5 minutes to ensure uniform and thorough heating of the cylindrical test bar.

[0052] Step 4) Select welding parameters with high friction pressure and low rotation speed to complete the entire welding process.

[0053] The friction welding process after preheating employs a low-speed, high-pressure welding technique. In this embodiment, a speed of 400 rpm, a welding pressure of 300 MPa, and an upsetting pressure of 360 MPa are selected. An axial shortening control welding method is used, with the axial shortening controlled at 5 mm.

[0054] See Figure 1 As shown, in the friction welding machine, GH4169 high-temperature alloy is selected at the feed end, and TC4 titanium alloy is used as the rotating end. The preheated material should be quickly friction welded after being removed from the muffle furnace to prevent a significant drop in interface temperature.

[0055] After the welding process is completed, the workpiece is removed and placed on a refractory floor to cool down naturally.

[0056] Example 2

[0057] Same as Example 1, except that the preheating temperature is set to 970°C.

[0058] Example 3

[0059] Same as Example 1, except that the preheating temperature is set to 990°C.

[0060] To illustrate the preheating method for rotary friction welding of TC4 titanium alloy / GH4169 high-temperature alloy dissimilar metals provided by the present invention, Example 1 is used as an example and described in conjunction with the accompanying drawings.

[0061] The experimental materials used were TC4 titanium alloy / GH4169 high-temperature alloy, and welding tests were conducted using a preheating welding method. The experimental results (joint macroscopic morphology, joint tensile test curves) and actual data are shown below. Figure 1-3 .

[0062] Figure 2 For the preheated friction welding specimen, the friction welded joint after preheating treatment showed obvious macroscopic plastic deformation on the GH4169 side.

[0063] Figure 3 Figure (a) shows the macroscopic morphology of the joint after preheating treatment, and Figure (b) shows the macroscopic morphology of the joint without preheating treatment. Observation of the macroscopic morphology of the joint reveals that after preheating treatment, the deformation on the TC4 base metal side is mainly concentrated near the weld interface. On the GH4169 base metal side, the deformation exhibits a gradient, gradually decreasing with increasing distance from the weld interface. Without preheating treatment, no deformation occurs on the GH4169 side, and the deformation is mainly concentrated on the TC4 side.

[0064] See Figure 4 As shown, Example 1 provides a welded TC4 titanium alloy / GH4169 high-temperature alloy joint that improves the "plastic deformation mismatch" problem. The difficult-to-deform GH4169 high-temperature alloy undergoes significant plastic deformation, making the deformation of GH4169 high-temperature alloy and TC4 titanium alloy more coordinated. This welding method significantly improves the weld strength, enabling the joint strength to reach the 500 MPa level.

[0065] It should be noted that after preheating, the GH4169 side of the joint undergoes significant deformation, the forming quality of the joint is significantly improved, and the joint strength before heat treatment is about 150 MPa, while the joint strength after preheating can reach 500 MPa.

[0066] This invention describes preferred embodiments and their effects. However, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to include both the preferred embodiments and all changes and modifications falling within the scope of this invention.

[0067] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preheating TC4 titanium alloy / GH4169 high-temperature alloy dissimilar metal rotary friction welding, characterized in that, Includes the following steps: Heat the GH4169 high-temperature alloy to 970~990℃ for preheating, hold for 5~10 minutes, and then perform friction welding with TC4 titanium alloy. During friction welding, place the preheated GH4169 high-temperature alloy at the feed end of the friction welding machine, and use the TC4 titanium alloy as the rotating end. During friction welding, the rotation speed should be ≤600 rpm, the welding pressure ≥300 MPa, and the upsetting pressure ≥300 MPa. During friction welding, a welding method that controls axial shortening is used, with the axial shortening controlled at 5mm. The heating rate during preheating is 5~10℃ / min.

2. The preheating method for rotary friction welding of TC4 titanium alloy / GH4169 high-temperature alloy dissimilar metals according to claim 1, characterized in that, During the preheating process, the preheating temperature is monitored using thermocouples or infrared thermometers; when induction heating is used for preheating, thermocouples or infrared thermometers are used for temperature monitoring; when a muffle furnace is used for preheating, thermocouples are used for temperature monitoring.

3. The preheating method for rotary friction welding of TC4 titanium alloy / GH4169 high-temperature alloy dissimilar metals according to claim 2, characterized in that, When using thermocouples for temperature monitoring, the thermocouple measuring tip must be in close contact with the workpiece surface. When using an infrared thermometer for temperature monitoring, the infrared emissivity of the material must be calibrated to avoid inaccurate temperature measurements.

4. The preheating method for rotary friction welding of TC4 titanium alloy / GH4169 high-temperature alloy dissimilar metals according to claim 1, characterized in that, Preheating is performed using a muffle furnace or induction heating.

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