Method and device for reducing residual stress of titanium alloy welded joint by cold spraying
The residual stress of titanium alloy welded joints is reduced by cold spraying, which solves the problems of complex parameter adjustment and low control accuracy in the prior art, and significantly improves the fatigue strength and service life of the welded joints.
Patent Information
- Application Number
- CN202510440845.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-09
- Publication Date
- 2025-05-30
AI Technical Summary
The residual stress generated during welding of titanium alloy parts will reduce the load-bearing capacity and service life of the components. The existing methods to reduce residual stress have problems such as complex parameter adjustment, low control accuracy and limited application range.
The cold spraying method is adopted to perform cold spraying treatment by spraying powder gas with a pressure of 1.6 to 3.6MPa and a temperature of 25 to 300°C and aerosolized powder with a particle size of 45 to 106μm. The spraying is performed in a single or multiple passes along the welds to reduce the residual stress of the titanium alloy welded joint.
The cold spraying method performs solid-state deposition at low temperatures, avoids the material phase change and thermal stress problems in high-temperature processes, significantly reduces residual stress, has higher parameter adjustment accuracy and controllability, and improves the fatigue strength and service life of the welded joints.
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Figure CN120060841A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of titanium alloy part welding, and particularly to a method for reducing the residual stress of titanium alloy welded joints. Background Art
[0002] Titanium alloy parts are widely used in important fields such as aerospace, automotive manufacturing, medical devices, and energy. To ensure their safety and reliability in various fields, it is very important to improve the performance and service life of titanium alloy parts.
[0003] When welding titanium alloy parts, the weld area is subjected to concentrated heating, the temperature rises rapidly and expands, while the area far from the weld has a lower temperature and a smaller degree of expansion. This non-uniform thermal expansion causes the weld area to be restricted by the surrounding materials and unable to elongate freely, thus generating compressive stress. Subsequently, during the cooling process, the weld area shrinks and is again restricted by the surrounding colder materials and unable to shorten freely, finally forming residual tensile stress.
[0004] At the same time, at high temperatures, the materials in the weld area will undergo plastic deformation; when cooling, this plastic deformation cannot be fully restored, resulting in internal stress in the materials. The residual stress will be superimposed on the external load, leading to local stress concentration in the component, thereby reducing its load-bearing capacity.
[0005] The residual stress will also be superimposed on the external stress, increasing the actual stress level of the component, thereby accelerating the initiation and propagation of fatigue cracks and shortening the fatigue life of the component; the residual stress may also cause local hardening or softening of the material, affecting its mechanical properties.
[0006] Existing methods for reducing residual stress mainly include heat treatment, vibration aging, mechanical stretching, etc. Among them, the heat treatment method is to make the internal plastic deformation or phase transformation of the material through heat treatment processes such as annealing, tempering, or stress relief annealing, thereby releasing the residual stress. This method may change the microstructure and mechanical properties of the material. For large or complex components, it is difficult to uniformly heat, which may lead to new non-uniform stress distribution; the vibration aging method is to generate microscopic plastic deformation inside the component by applying mechanical vibration, thereby releasing the residual stress. This method has limited effect on brittle materials, and the vibration parameters need to be precisely controlled, otherwise the stress may not be fully released; the mechanical stretching method is to apply an external tensile load to the component to make it undergo plastic deformation, thereby offsetting the welding residual stress. This method is only applicable to components with simple shapes and is difficult to implement for complex structures.
[0007] Therefore, it is necessary to develop a new method to reduce or eliminate the residual stress of titanium alloy part welded joints. Summary of the Invention
[0008] The object of the present invention is to avoid the deficiencies of the prior art and provide a method that effectively reduces the residual stress of a welded joint by means of cold spraying, improves the load-bearing capacity of a titanium alloy welded component after welding, and extends its service life.
[0009] To achieve the above object, the technical solution adopted by the present invention is as follows: A method for reducing the residual stress of a titanium alloy welded joint by means of cold spraying, comprising: Using a powder spraying gas with a pressure of 1.6 - 3.6 MPa and a temperature of 25 - 300 °C to fully expand the powder spraying gas and improve the acceleration effect of the powder spraying gas during cold spraying treatment; Using gas atomized powder with a particle size of 45 - 106 μm as the spraying powder; With the distance between the spray gun and the weld surface being 15 - 35 mm and the moving speed of the spray gun being 30 - 50 mm / s, performing single-pass or multi-pass cold spraying treatment in a reciprocating manner along the upper and lower parts of the weld, thus completing the process of reducing the residual stress of the titanium alloy welded joint.
[0010] Further, the spraying powder is gas atomized spherical 304L powder or Fe powder.
[0011] Further, the cold spraying treatment process is as follows: Using nitrogen or compressed air with a pressure of 1.6 MPa or 2.6 MPa or 3.6 MPa and a temperature of 25 °C as the powder spraying gas; With the distance between the spray gun and the weld surface being 15 mm or 25 mm or 35 mm and the moving speed of the spray gun being 50 mm / s, performing 1 - 4 passes of cold spraying treatment in a reciprocating manner along the upper and lower parts of the weld.
[0012] Further, the weld is a butt fusion weld or a lap fusion weld.
[0013] The present invention also provides a device for implementing the method for reducing the residual stress of a titanium alloy welded joint by means of cold spraying, comprising: a high-pressure gas source tank for storing the powder spraying gas and sending it out under high pressure; One high-pressure outlet pipeline of the high-pressure gas source tank is connected to the inlet of a powder feeder, and the other high-pressure outlet pipeline is connected to the inlet of a gas heater; The outlet pipeline of the powder feeder is connected to the inlet of a supersonic Laval nozzle, so that the powder spraying gas sends the spraying powder supplied by the powder feeder to the inlet of the supersonic Laval nozzle; The outlet pipeline of the gas heater is also connected to the inlet of the supersonic Laval nozzle, so that the powder spraying gas heated in the gas heater is also sent to the inlet of the supersonic Laval nozzle; After heating, the powder spraying gas and the spraying powder form a high-speed particle flow in the supersonic Laval nozzle, and are ejected through a spray gun connected to the outlet of the supersonic Laval nozzle onto the weld of the titanium alloy welded part.
[0014] Furthermore, the powder feeder is a rotary disk type powder feeder, which is used to ensure the continuous and uniform powder feeding.
[0015] Furthermore, the spray gun is installed on a gun-holding robotic arm, and the gun-holding robotic arm is a six-axis gun-holding robotic arm, which is used to make the high-speed particle flow in the spray gun impact the weld surface area of the titanium alloy welded part uniformly along the welding path.
[0016] Furthermore, the expansion ratio of the supersonic Laval nozzle is 5.0 - 8.0, and the length of the expansion section is 200 - 280 mm, so as to ensure a better powder acceleration effect.
[0017] Furthermore, the expansion ratio of the supersonic Laval nozzle is 8.0, and the length of the expansion section is 280 mm.
[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Cold spraying is a solid-state deposition process carried out at a temperature far below the melting point of the material. This low-temperature characteristic avoids problems such as material phase change, grain growth, and thermal stress caused by high temperature in the traditional thermal spraying process, thus significantly reducing the residual stress. 2. The parameter adjustment of the traditional method is complex and the control accuracy is low. The cold spraying technology has higher parameter adjustment accuracy and controllability. By adjusting key parameters such as gas pressure, gas temperature, and spraying distance, the residual stress can be precisely controlled, and the performance of the welded joint can be optimized. 3. From the perspectives of environmental protection and energy conservation, compared with the traditional high-temperature process, the cold spraying low-temperature process reduces energy consumption and pollution, meeting the environmental protection requirements. This advantage is more prominent especially in fields with strict environmental protection requirements such as aerospace and automobile manufacturing. 4. During the cold spraying process, the high-speed particles impact the surface of the substrate to produce plastic deformation, which helps to release the original stress of the substrate. At the same time, a coating is formed through mechanical interlocking, reducing the generation of new stress. Description of the Drawings
[0019] Figure 1 is the working principle diagram of the method of the present invention; Figure 2 is the residual stress result diagram of the embodiment of the present invention.
[0020] In the figure: 1 - high-pressure gas source tank, 2 - powder feeder, 3 - gas heater, 4 - spraying powder, 5 - supersonic Laval nozzle, 6 - spray gun, 7 - high-speed particle flow, 8 - titanium alloy welded part. Detailed Embodiment
[0021] The principles and features of the present invention will be described below in conjunction with the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.
[0022] To achieve the above object, the present invention provides the following specific embodiments: Example 1: A method for reducing the residual stress of a titanium alloy welded joint by cold spraying, comprising: Using a powder spraying gas with a pressure of 1.6 - 3.6 MPa and a temperature of 25 - 300 °C to fully expand the powder spraying gas and improve the acceleration effect of the powder spraying gas in the cold spraying process; Using an air atomized powder with a particle size of 45 - 106 μm as the spraying powder; the spraying powder is air atomized spherical 304L powder or Fe powder; With the distance between the spray gun and the weld surface being 15 - 35 mm and the moving speed of the spray gun being 30 - 50 mm / s, performing single - pass or multi - pass cold spraying treatment along the upper and lower parts of the weld in a cyclic manner, thus completing the process of reducing the residual stress of the titanium alloy welded joint.
[0023] Among them, the weld is a butt fusion weld or a lap fusion weld.
[0024] Example 2: The same as Example 1, except that the cold spraying treatment process is as follows: Using nitrogen or compressed air with a pressure of 1.6 MPa or 2.6 MPa or 3.6 MPa and a temperature of 25 °C as the powder spraying gas; With the distance between the spray gun and the weld surface being 15 mm or 25 mm or 35 mm and the moving speed of the spray gun being 50 mm / s, performing 1 - 4 passes of cold spraying treatment along the upper and lower parts of the weld in a cyclic manner.
[0025] Example 3: The same as Example 1, except that: A method for reducing the residual stress of a titanium alloy welded joint by cold spraying, comprising: Using a powder spraying gas with a pressure of 2.4 MPa and a temperature of 150 °C to fully expand the powder spraying gas and improve the acceleration effect of the powder spraying gas in the cold spraying process; Using an air atomized powder with a particle size of 60 μm as the spraying powder; the spraying powder is air atomized spherical 304L powder; With the distance between the spray gun and the weld surface being 23 mm and the moving speed of the spray gun being 38 mm / s, performing single - pass or multi - pass cold spraying treatment along the upper and lower parts of the weld in a cyclic manner, thus completing the process of reducing the residual stress of the titanium alloy welded joint.
[0026] Among them, the weld is a butt fusion weld.
[0027] Example 4: The same as Example 1, except that: A method for reducing the residual stress of a titanium alloy welded joint by cold spraying includes: Using a powder spraying gas with a pressure of 3.0 MPa and a temperature of 230 °C to fully expand the powder spraying gas and improve the acceleration effect of the powder spraying gas in the cold spraying process; Using gas atomized powder with a particle size of 95 μm as the spraying powder; the spraying powder is gas atomized spherical Fe powder; With the distance between the spray gun and the weld surface being 32 mm and the moving speed of the spray gun being 45 mm / s, performing single-pass or multi-pass cold spraying treatment along the upper and lower cycles of the weld, thus completing the process of reducing the residual stress of the titanium alloy welded joint.
[0028] Among them, the weld is a lap fusion weld.
[0029] Example 5: As Figure 1 shown, the present invention also provides a device for implementing the method of reducing the residual stress of a titanium alloy welded joint by cold spraying, including: a high-pressure gas source tank 1 for storing the powder spraying gas and sending it out under high pressure; One high-pressure outlet pipeline of the high-pressure gas source tank 1 is connected to the inlet of the powder feeder 2, and the other high-pressure outlet pipeline is connected to the inlet of the gas heater 3; The outlet pipeline of the powder feeder 2 is connected to the inlet of the supersonic Laval nozzle 5, so that the powder spraying gas sends the spraying powder supplied by the powder feeder 2 to the inlet of the supersonic Laval nozzle 5; The outlet pipeline of the gas heater 3 is also connected to the inlet of the supersonic Laval nozzle 5, so that the powder spraying gas heated in the gas heater 3 is also sent to the inlet of the supersonic Laval nozzle 5; The heated powder spraying gas and the spraying powder form a high-speed particle flow 7 in the supersonic Laval nozzle 5 and are sprayed out through the spray gun 6 connected to the outlet of the supersonic Laval nozzle 5 to the weld of the titanium alloy welded part 8.
[0030] Among them, the expansion ratio of the supersonic Laval nozzle 5 is 5.0 - 8.0, and the length of the expansion section is 200 - 280 mm to ensure a better powder acceleration effect.
[0031] Example 6: The same as Example 5, except that the powder feeder 2 is a rotary disk type powder feeder for ensuring continuous and uniform powder feeding.
[0032] Example 7: The same as Example 5, except that the spray gun 6 is installed on a gun holding robotic arm, and the gun holding robotic arm is a six-axis gun holding robotic arm for enabling the high-speed particle flow 7 in the spray gun 6 to uniformly impact the weld surface area of the titanium alloy welded part 8 along the welding path.
[0033] Example 8: The same as Example 5, except that the expansion ratio of the supersonic Laval nozzle 5 is 8.0 and the length of the divergent section is 280 mm.
[0034] As Figure 1 , 2 shown, in order to further illustrate the technical solutions and effects of the present invention, the following specific examples are provided: See Figure 1 , after loading the spraying powder 4 into the powder feeder 2, connect the high-pressure gas source tank 1 and start the gas heater 3 to preheat the gas. The preheated high-pressure gas carries the spraying powder 4 through the supersonic Laval nozzle 5 to form a high-speed particle stream 7.
[0035] The operator manipulates the gun-holding robotic arm to hold the spray gun 6, so that the high-speed particle stream 7 in the gun impacts the weld surface area of the titanium alloy welded part 8 evenly along the welding path. This process generates compressive stress on the joint surface, reduces the residual stress, and thus improves the fatigue strength and service life of the joint. Specifically: I. Perform butt welding of flat plates on titanium alloy materials by using the fusion welding method; II. According to the position of the weld area, adjust the program through the control panel of the gun-holding robotic arm to determine that the moving trajectory of the spray gun is a reciprocating movement from top to bottom in the direction perpendicular to the weld. The number of spraying passes of the spray gun is 1 pass, 2 passes, and 4 passes respectively. The distance between the spray gun and the weld surface is 15 mm, 25 mm, and 35 mm, and the moving speed of the spray gun is 50 mm / s; III. Load the spraying powder into the dust-removed powder feeder, ensure that the spraying powder in the powder feeder is pure and free of impurities, tighten the sealing nut on the powder feeder cover to ensure the tightness of the powder feeder. The powder feeder is a rotary powder feeder, the spraying powder is gas-atomized spherical 304L powder, and the particle size range of the spraying powder is 45 - 106 μm; IV. Use a gas heater to heat the gas sent out by the high-pressure gas source device to make the gas fully expand and improve the acceleration effect of the gas. The gas is high-pressure nitrogen, the pressure of the gas is 1.6 MPa, 2.6 MPa, and 3.6 MPa, and the heating temperature of the gas is 25 °C.
[0036] V. The gun-holding robotic arm holds the spray gun. The spraying powder, through the acceleration of the gas, flows through the supersonic Laval nozzle in the spray gun to form a high-speed particle stream, and performs shot peening strengthening treatment on the weld surface. The gun-holding robotic arm is a 6-axis gun-holding robotic arm; the expansion ratio of the supersonic Laval nozzle is 8.0, and the length of the divergent section of the supersonic Laval nozzle is 280 mm.
[0037] Referring to GB / T31310-2014, the blind hole method was used to detect the residual stress of the GTAW joints of titanium alloy. A total of nine groups of experimental tests were carried out. The gas was high-pressure nitrogen, the gas heating temperature was 25°C, and the spray gun moving speed was 50mm / s. Among them, the gas pressure of the No. 1 specimen was 1.6MPa, the spraying distance was 15mm, and the number of spraying passes was 1 pass; The gas pressure of the No. 2 specimen was 2.6MPa, the spraying distance was 15mm, and the number of spraying passes was 2 passes; The gas pressure of the No. 3 specimen was 3.6MPa, the spraying distance was 15mm, and the number of spraying passes was 4 passes; The gas pressure of the No. 4 specimen was 1.6MPa, the spraying distance was 25mm, and the number of spraying passes was 2 passes; The gas pressure of the No. 5 specimen was 2.6MPa, the spraying distance was 25mm, and the number of spraying passes was 4 passes; The gas pressure of the No. 6 specimen was 3.6MPa, the spraying distance was 25mm, and the number of spraying passes was 1 pass; The gas pressure of the No. 7 specimen was 1.6MPa, the spraying distance was 35mm, and the number of spraying passes was 4 passes; The gas pressure of the No. 8 specimen was 2.6MPa, the spraying distance was 35mm, and the number of spraying passes was 1 pass; The gas pressure of the No. 9 specimen was 3.6MPa, the spraying distance was 35mm, and the number of spraying passes was 2 passes.
[0038] The results are as Figure 2 shown: By comparing the residual stress values at the weld center before and after spraying, it can be clearly seen that for the GTAW joints of titanium alloy after spraying treatment, the residual stress is significantly reduced. Among them, the No. 3 specimen with a gas pressure of 3.6MPa, a spraying distance of 15mm, and 4 spraying passes has the best effect. The residual stress value is reduced from 30.2MPa to -508.6MPa, a decrease of 538.8MPa, which improves the residual stress of the GTAW joints of titanium alloy and can enhance the fatigue performance and service life of the joints.
[0039] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A method for reducing residual stress in titanium alloy welded joints by cold spraying, characterized in that: include: The powder spraying gas with a pressure of 1.6 to 3.6 MPa and a temperature of 25 to 300°C is used to fully expand the powder spraying gas and improve the acceleration effect of the powder spraying gas in the cold spraying process; The aerosolized powder with a particle size of 45 to 106 μm is used as the spray powder; With the distance between the spray gun and the weld surface being 15 to 35 mm and the moving speed of the spray gun being 30 to 50 mm / s, single or multiple passes of cold spraying treatment are performed repeatedly up and down the weld to complete the process of reducing the residual stress of the titanium alloy welded joint.
2. The method for reducing residual stress in titanium alloy welded joints by cold spraying according to claim 1, characterized in that: The spraying powder is atomized spherical 304L powder or Fe powder.
3. The method for reducing residual stress in titanium alloy welded joints by cold spraying according to claim 1, characterized in that: The cold spraying process is as follows: Use nitrogen or compressed air with a pressure of 1.6MPa, 2.6MPa or 3.6MPa and a temperature of 25°C as the powder spraying gas; The distance between the spray gun and the weld surface is 15mm, 25mm or 35mm, the moving speed of the spray gun is 50mm / s, and 1-4 passes of cold spraying are performed reciprocatingly along the upper and lower sides of the weld.
4. The method for reducing residual stress in titanium alloy welded joints by cold spraying according to any one of claims 1 to 3, characterized in that: The weld is a butt fusion weld or a lap fusion weld.
5. A device for realizing the method of reducing residual stress of titanium alloy welded joints by cold spraying as described in claims 1-4, characterized in that: include: A high-pressure gas source tank (1) for storing powder spraying gas and delivering the powder spraying gas at high pressure; One high-pressure outlet pipeline of the high-pressure gas source tank (1) is connected to the inlet of the powder feeder (2), and the other high-pressure outlet pipeline is connected to the inlet of the gas heater (3); The outlet pipeline of the powder feeder (2) is connected to the inlet of the supersonic laval nozzle (5), so that the powder spraying gas delivers the spraying powder supplied by the powder feeder (2) to the inlet of the supersonic laval nozzle (5); The outlet pipeline of the gas heater (3) is also connected to the inlet of the supersonic laval nozzle (5), so that the powder spraying gas heated in the gas heater (3) is also sent to the inlet of the supersonic laval nozzle (5); The heated powder spraying gas and the spraying powder form a high-speed particle flow (7) in the supersonic laval nozzle (5), and are sprayed to the weld of the titanium alloy weldment (8) through a spray gun (6) connected to the outlet of the supersonic laval nozzle (5).
6. The device according to claim 5, characterized in that The powder feeder (2) is a turntable powder feeder, which is used to ensure continuous and uniform powder feeding.
7. The device according to claim 5, characterized in that The spray gun (6) is mounted on a gun holding mechanical arm, and the gun holding mechanical arm is a six-axis gun holding mechanical arm, which is used to make the high-speed particle flow (7) in the spray gun (6) evenly impact the weld surface area of the titanium alloy weldment (8) along the welding path.
8. The device according to claim 5, characterized in that The expansion ratio of the supersonic laval nozzle (5) is 5.0-8.0, and the expansion section length is 200-280 mm, so as to ensure a better powder acceleration effect.
9. The device according to any one of claims 5 to 8, characterized in that: The expansion ratio of the supersonic laval nozzle (5) is 8.0, and the length of the expansion section is 280 mm.