Method and device for local nitriding of titanium alloy surface

Abstract

The present invention provides a method and device for local nitriding of titanium alloy surface, and relates to the technical field of material surface treatment. The method for local nitriding of titanium alloy surface comprises: vacuuming the surface of the area to be nitrided of the titanium alloy workpiece; placing the surface of the area to be nitrided of the titanium alloy workpiece in a nitrogen atmosphere; and performing nitriding treatment on the area to be nitrided of the titanium alloy workpiece by laser scanning. The device for local nitriding of titanium alloy surface comprises a side wall of a vacuum box having a transparent area, and a side wall opposite to the transparent area having an operating port, the position of the operating port corresponding to the position of the transparent area. When working, the side of the vacuum box having the operating port is buckled on the surface of the area to be nitrided of the titanium alloy workpiece, the laser emission direction is toward the transparent area, and the vacuum box has a nitrogen inlet. The method and device have high nitriding efficiency and stable nitriding effect, and the workpiece is not affected, thereby solving the problems of workpiece deformation and inefficiency caused by long-term high-temperature and high-pressure nitriding.

Description

Technical Field

[0001] The invention relates to the technical field of material surface treatment, and in particular to a method and a device for local nitriding of a titanium alloy surface. Background Art

[0002] Titanium alloys have attracted much attention due to their low density, high specific strength, corrosion resistance, and excellent low-temperature and high-temperature resistance. However, due to the low hardness and poor wear resistance of the titanium alloy surface, it is very sensitive to adhesive wear and micro-wear, which greatly limits its application range. At present, how to improve the hardness and wear resistance of titanium alloys has become one of the hot topics in the field of titanium alloy research. Forming nitrides on the surface of titanium and titanium alloys is an effective way to improve their hardness, wear resistance and fatigue resistance. Traditional surface modification technologies, such as plasma spraying, surface chemical heat treatment, vapor deposition technology, electroplating, ion implantation technology, etc., can effectively improve the wear resistance of titanium alloy surfaces. However, these methods all have certain disadvantages, such as the need to heat the workpiece for a long time at high temperature, causing deformation of the workpiece, and low efficiency; or because the titanium alloy surface coating has a weak bonding force with the titanium substrate, it is easy to peel off, etc. The use of laser surface nitriding technology can obtain a nitride layer with high hardness, wear resistance and corrosion resistance, which is in-situ metallurgical bonding with the substrate, has high bonding strength, and is not easy to peel off. However, there are still many problems in the existing technology when performing nitriding treatment, which means that the nitriding method needs to be further optimized.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The purpose of the present invention is to provide a method and device for local nitriding of titanium alloy surface with good nitriding effect.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] In a first aspect, an embodiment of the present invention provides a method for local nitriding of a titanium alloy surface, comprising: evacuating the surface of the titanium alloy workpiece in the area to be nitrided; placing the surface of the titanium alloy workpiece in the area to be nitrided in a nitrogen atmosphere; and performing nitriding treatment on the titanium alloy workpiece in the area to be nitrided by laser scanning.

[0007] In an optional embodiment, according to the thickness requirement of the nitriding layer, during the nitriding treatment, the laser power is 200-6000W, the scanning frequency is 50-1000Hz, and the scanning speed is 200-1000mm / s;

[0008] In an alternative embodiment, the scan overlap area is 0-0.5 mm.

[0009] In an optional embodiment, during nitridation treatment, the laser scanning is positively defocused, the distance from the laser head to the surface of the area to be nitrided is within the laser focal length range, and the diameter of the laser spot is less than or equal to 2 mm.

[0010] In an optional embodiment, before the nitridation treatment, the surface of the area to be nitrided is cleaned by laser scanning.

[0011] In an optional embodiment, during surface cleaning, the laser power is 500-1000 W, the scanning frequency is 500-1000 Hz, and the scanning speed is 200-1000 mm / s.

[0012] In an optional embodiment, the surface of the area to be nitrided is cleaned when the vacuum is evacuated to a pressure less than or equal to 100 Pa.

[0013] In an optional embodiment, the surface of the titanium alloy workpiece in the area to be nitrided is placed in a nitrogen atmosphere. According to actual requirements, when the gas pressure reaches 100 to 1000 Pa, laser scanning is used to perform nitriding treatment on the titanium alloy workpiece in the area to be nitrided.

[0014] In an optional embodiment, placing the surface of the titanium alloy workpiece in the region to be nitrided in a nitrogen atmosphere is to fill nitrogen into a closed space formed on the surface of the titanium alloy workpiece in the region to be nitrided;

[0015] In an optional embodiment, a dilution gas is introduced into the closed space while nitrogen is filled, and the dilution gas is an inert gas.

[0016] After the surface is nitrided, air is introduced and after the pressure is balanced, it can be quickly moved to the next processing position.

[0017] In the second aspect, an embodiment of the present invention provides a local nitriding device for the surface of titanium alloy, including a laser scanning system, a vacuum box and an exhaust pump. The laser emission direction of the laser scanning system is toward the vacuum box, the vacuum box is connected to the exhaust pump, and the vacuum box is provided with a nitrogen inlet.

[0018] In an optional embodiment, one side wall of the vacuum box has a transparent area, and an operation port is provided on a side wall opposite to the transparent area, and the position of the operation port corresponds to the position of the transparent area. When working, the side of the vacuum box with the operation port is buckled on the surface of the area to be nitrided of the titanium alloy workpiece, and the laser emission direction of the laser scanning system is toward the transparent area;

[0019] In an optional embodiment, the titanium alloy surface local nitriding device further includes a displacement control mechanism for controlling the distance from the laser scanning system to the operation port, and the displacement control mechanism is connected to the vacuum box and the laser scanning system;

[0020] In an optional embodiment, the displacement control mechanism includes a motor, a connecting rod and a connecting piece, the connecting piece is connected to the laser scanning system, an internal thread is provided in the connecting piece, the connecting rod is vertically arranged, one end of which is connected to the motor, and the other end surface of the connecting rod is provided with an external thread and extends into the connecting piece to match the internal thread;

[0021] In an optional embodiment, the titanium alloy surface local nitriding device further includes a pressure gauge, and the pressure gauge is used to test the air pressure in the vacuum box;

[0022] In an optional embodiment, there are multiple vacuum pumps, and the multiple vacuum pumps are all connected to the vacuum box;

[0023] In an optional embodiment, the titanium alloy surface local nitriding device further includes a sealing member, which is arranged at the edge of the operation port;

[0024] In an optional embodiment, the transparent area is a transparent plate or a lens;

[0025] In an optional embodiment, the device for local nitriding of the titanium alloy surface further includes a solenoid valve, which is disposed at the nitrogen inlet.

[0026] In an optional embodiment, the device for local nitriding of the titanium alloy surface further includes a control system, which is communicatively connected with the laser scanning system, the motor, the pressure gauge, the solenoid valve, and the vacuum pump.

[0027] The beneficial effects of the embodiments of the present invention include:

[0028] Laser scanning nitriding is performed in a low-pressure environment. On the premise of etching a nitrided layer of the same thickness, the laser power is reduced; and because a low-power rapid laser is used to scan a local area, the nitriding efficiency is high and the nitriding effect is stable, the workpiece is not affected, and the problems of workpiece deformation and inefficiency caused by long-term high-temperature and high-pressure nitriding are solved. In a preferred embodiment, the local vacuum box is an open box, and a closed state is achieved by using a pressure difference. The small volume is conducive to the formation of a low-pressure environment and is conducive to rapid movement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a front view of a device for local nitriding of titanium alloy surface;

[0031] Figure 2It is the left view of the local nitriding device on the titanium alloy surface;

[0032] Figure 3 It is the right view of the local nitriding device on the titanium alloy surface;

[0033] Figure 4 Schematic diagram of signal transmission of various components in the local nitriding device on the titanium alloy surface.

[0034] Icons: 100- local nitriding device for titanium alloy surface; 101- control system; 110- laser scanning system; 120- vacuum box; 112- laser beam; 121- transparent area; 122- operation port; 123- nitrogen inlet; 124- solenoid valve; 130- displacement control mechanism; 131- motor; 132- connecting rod; 133- connecting piece; 140- pressure gauge; 150- vacuum pump; 151- vacuum pipe; 160- seal; 200- titanium alloy workpiece. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0038] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear to indicate an orientation or position relationship, they are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0039] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0040] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0041] The inventor has made creative efforts to find that the existing technology usually uses gas side blowing to provide nitrogen under atmospheric pressure, which results in unstable gas pressure and low laser absorption rate; and due to the instability of laser energy, the thickness of the nitrided layer is uneven, which in turn causes large residual stress and easy crack formation; or due to long-term high-temperature and high-pressure nitriding, the workpiece is deformed and inefficient. In response to this problem, the inventor proposed this solution to improve the nitriding treatment effect.

[0042] like Figure 1-Figure 3 As shown, an embodiment of the present invention provides a local nitriding device 100 for the surface of a titanium alloy, comprising a laser scanning system 110, a vacuum box 120 and an exhaust pump 150. The laser emission direction of the laser scanning system 110 is toward the vacuum box 120. The vacuum box 120 is connected to the exhaust pump 150. The vacuum box 120 is provided with a nitrogen inlet 123.

[0043] Furthermore, one side wall of the vacuum box 120 has a transparent area 121, and an operating port 122 is provided on the side wall opposite to the transparent area 121. The position of the operating port 122 corresponds to the position of the transparent area 121. When in operation, the side of the vacuum box 120 with the operating port 122 is buckled onto the surface of the titanium alloy workpiece in the area to be nitrided, and the laser emission direction of the laser scanning system 110 is toward the transparent area 121.

[0044] When performing local nitriding on the titanium alloy surface, the operating port 122 of the vacuum box 120 is buckled on the area to be nitrided of the titanium alloy workpiece 200. The distance between the laser head and the titanium alloy workpiece is adjusted, and the vacuum pump 150 is started to evacuate the vacuum box 120 to make the vacuum box in a low-pressure state, and then nitrogen is filled in for laser nitriding; or when it is in a low-pressure state, the titanium alloy surface is first cleaned with laser, and then nitrogen is introduced for laser nitriding.

[0045] The vacuum box 120 is an open box that uses pressure difference to achieve a closed state. Its small size is conducive to the formation of a low-pressure environment and is conducive to rapid movement.

[0046] Specifically, the transparent area 121 is a transparent plate or a lens.

[0047] Preferably, the titanium alloy surface local nitriding device 100 further includes a sealing member 160, which is arranged at the edge of the operation port. The sealing member 160 can prevent the vacuum box 120 from leaking after being buckled onto the workpiece surface.

[0048] Furthermore, the titanium alloy surface local nitriding device 100 also includes a displacement control mechanism 130 for controlling the distance from the laser scanning system to the operation port, and the displacement control mechanism 130 is connected to the vacuum box 120 and the laser scanning system 110.

[0049] The displacement control mechanism 130 is used to control the distance between the laser scanning system 110 and the vacuum box 120 so that the distance of the surface of the area to be nitrided is within the laser focus range.

[0050] Furthermore, the displacement control mechanism 130 includes a motor 131, a connecting rod 132 and a connecting piece 133. The connecting piece 133 is connected to the laser scanning system 110. An internal thread is provided in the connecting piece 133. The connecting rod 132 is vertically arranged, one end of which is connected to the motor 131 and is driven to rotate by the motor 131. The other end surface of the connecting rod 132 is provided with an external thread and extends into the connecting piece 133 to cooperate with the internal thread.

[0051] When the distance between the vacuum box 120 and the laser scanning system 110 needs to be adjusted, the motor 131 is started, and the connecting rod 132 is rotated by the forward or reverse rotation of the motor 131 , and the laser scanning system 110 is lifted up and down under the action of the thread.

[0052] Furthermore, in order to keep the laser scanning system 110 more firmly installed, the number of motors 131, connectors 133 and connecting rods 132 is 2, two connectors 133 are respectively arranged on opposite sides of the laser scanning system 110, and two motors 131 and two connecting rods 132 are arranged one by one. When in use, the two motors 131 run synchronously.

[0053] Furthermore, the titanium alloy surface local nitriding device 100 further includes a pressure gauge 140, which is used to test the air pressure in the vacuum box 120. During the nitriding process, the air intake or exhaust can be controlled by observing the air pressure in the vacuum box 120 displayed by the pressure gauge 140.

[0054] Preferably, in order to improve the air extraction efficiency, there are multiple air extraction pumps 150, and each of the air extraction pumps 150 is connected to the vacuum box 120. Each air extraction pump 150 is connected to the vacuum box 120 through an air extraction pipe 151.

[0055] The nitrogen inlet 123 is also provided with a solenoid valve 124 , through which the charging of nitrogen is controlled.

[0056] Furthermore, if Figure 4 As shown, the titanium alloy surface local nitriding device 100 also includes a control system 101, and the control system 101 is communicatively connected with the laser scanning system 110, the motor 131, the pressure gauge 140, the solenoid valve 124 and the vacuum pump 150.

[0057] Before nitriding treatment, the solenoid valve 124 is connected to an external nitrogen storage device. When the titanium alloy surface local nitriding device 100 is used, the control system 101 automatically controls the motor 131 to operate so that the laser scanning system 110 is raised and lowered to a suitable position; the pressure gauge 140 sends the pressure value it detects to the control system 101, and the control system 101 controls the start and stop of the vacuum pump 150. When the pressure reaches the preset value, the control system 101 controls the laser scanning system 110 to clean the surface of the workpiece; after cleaning, the solenoid valve 124 is controlled to open, the nitrogen inlet 123 is in a passage state, and nitrogen is filled into the vacuum box 120. When the pressure gauge 140 detects that the nitrogen pressure in the vacuum box 120 is at the preset value, the control system 101 controls the laser scanning system 110 to perform nitriding treatment on the surface of the workpiece.

[0058] The embodiment of the present invention provides a method for local nitriding of a titanium alloy surface, comprising:

[0059] The surface of the titanium alloy workpiece in the area to be nitrided is vacuumed; the surface of the titanium alloy workpiece in the area to be nitrided is placed in a nitrogen atmosphere; and laser scanning is used to perform nitriding treatment on the titanium alloy workpiece in the area to be nitrided.

[0060] Laser gas nitriding uses a laser beam to irradiate the surface of a workpiece in a nitrogen atmosphere, causing the surface to melt and form a molten pool. Under the irradiation of a high-energy laser beam, nitrogen undergoes a strong chemical and metallurgical interaction with the high-temperature titanium alloy liquid in the molten pool, thereby significantly improving the chemical composition and composition of the titanium alloy liquid, and finally rapidly solidifies to form a wear-resistant surface modification layer. In this process, the laser has two functions. One is to heat the workpiece as a heat source to form a liquid molten pool; on the other hand, the laser activates some nitrogen atoms into active nitrogen atoms in the local atmosphere.

[0061] The nitriding method provided by the present invention evacuates the surface of the local area that only needs nitriding, and performs laser scanning nitriding in a low-pressure environment. Under the premise of etching to obtain a nitrided layer of the same thickness, the laser power is reduced; and because a low-power rapid laser is used to scan the local area, the efficiency is high and the nitriding effect is stable, the workpiece is not affected, and the problems of workpiece deformation and inefficiency caused by long-term high-temperature and high-pressure nitriding are solved.

[0062] Specifically, the nitriding method is:

[0063] S1. Evacuate the surface of the titanium alloy workpiece in the area to be nitrided.

[0064] The vacuum box 120 is buckled on the surface of the area to be nitrided of the titanium alloy workpiece to form a closed space on the surface of the area to be nitrided of the titanium alloy workpiece. The position of the laser scanning system 110 is adjusted to ensure that after the laser scanning system 110 is powered on, the laser beam 112 just passes through the transparent area 121 and the distance from the laser head of the laser scanning system 110 to the surface of the area to be nitrided is within the laser focal length range.

[0065] The vacuum pump 150 is started to extract the air in the vacuum box 120 .

[0066] S2. Use laser scanning to clean the surface of the area to be nitrided.

[0067] When the vacuum pressure is less than or equal to 100 Pa, the vacuum pump 150 stops working. The laser scanning system 110 is started to clean the surface of the area to be nitrided.

[0068] Preferably, during surface cleaning, the laser power is 500-1000 W, the scanning frequency is 500-1000 Hz, and the scanning speed is 200-1000 mm / s.

[0069] S3, placing the surface of the titanium alloy workpiece in the area to be nitrided in a nitrogen atmosphere.

[0070] After the surface cleaning is completed, nitrogen or a mixture of nitrogen and a diluent gas is introduced into the vacuum box 120. The diluent gas is an inert gas.

[0071] The degree of nitriding can be adjusted by filling a mixed gas with different ratios of nitrogen and dilution gas.

[0072] S4, performing nitriding treatment on the area to be nitrided of the titanium alloy workpiece by using laser scanning.

[0073] When the pressure of the mixed gas reaches 100-1000 Pa, the introduction of nitrogen is stopped, and the laser scanning system 110 is started to perform nitriding treatment on the surface of the titanium alloy workpiece in the area to be nitrided.

[0074] Preferably, during the nitriding treatment, the laser power is 200-6000W, the scanning frequency is 50-1000Hz, and the scanning speed is 200-1000mm / s. Further preferably, in order to ensure that all the areas to be nitrided can be scanned, the scanning overlap area is set to 0-0.5mm.

[0075] Preferably, the laser scanning is positively defocused, the distance from the laser head to the surface of the area to be nitrided is within the laser focus range, and the diameter of the laser spot is less than or equal to 2 mm.

[0076] After the surface is nitrided, air is introduced and after the pressure is balanced, it can be quickly moved to the next processing position.

[0077] After the surface nitriding is completed, air is added, the pressure reaches equilibrium, the vacuum box 120 leaves the workpiece, and the processing is completed.

[0078] The invention provides a device and a method for nitriding a non-planar surface.

[0079] Example 1

[0080] The method for local nitriding of the titanium alloy surface provided in this embodiment is specifically as follows:

[0081] The area to be nitrided of the titanium alloy workpiece was evacuated to a pressure less than 100Pa, and then the surface of the workpiece was cleaned. During surface cleaning, the laser power was 500W, the scanning frequency was 500Hz, and the scanning speed was 200mm / s. Then nitrogen was filled into the vacuum box to make the surface pressure of the titanium alloy workpiece reach 1000Pa, and then laser scanning nitriding treatment was carried out with a laser power of 200W, a scanning frequency of 50Hz, and a scanning speed of 200mm / s.

[0082] Example 2

[0083] The method for local nitriding of the titanium alloy surface provided in this embodiment is specifically as follows:

[0084] The area to be nitrided of the titanium alloy workpiece was evacuated to a pressure less than 100Pa, and then the surface of the workpiece was cleaned. During surface cleaning, the laser power was 1000W, the scanning frequency was 1000Hz, and the scanning speed was 1000mm / s. Then nitrogen was filled into the vacuum box to make the surface pressure of the titanium alloy workpiece reach 500Pa, and then laser scanning nitriding treatment was carried out with a laser power of 6000W, a scanning frequency of 1000Hz, and a scanning speed of 1000mm / s.

[0085] Example 3

[0086] The method for local nitriding of the titanium alloy surface provided in this embodiment is specifically as follows:

[0087] The area to be nitrided of the titanium alloy workpiece was evacuated to a pressure less than 100Pa, and then the surface of the workpiece was cleaned. During surface cleaning, the laser power was 800W, the scanning frequency was 800Hz, and the scanning speed was 600mm / s. Then nitrogen was filled into the vacuum box to make the surface pressure of the titanium alloy workpiece reach 800Pa, and then laser scanning nitriding treatment was carried out with a laser power of 2000W, a scanning frequency of 300Hz, and a scanning speed of 500mm / s.

[0088] In summary, the local nitriding method for the titanium alloy surface provided by the present invention performs laser scanning nitriding in a low-pressure environment, which reduces the laser power while obtaining a nitrided layer of the same thickness through etching. Due to the use of low-power rapid laser scanning of the local area, the efficiency is high and the nitriding effect is stable, the workpiece is not affected, and the problems of workpiece deformation and inefficiency caused by long-term, high-temperature and high-pressure nitriding are solved.

[0089] The titanium alloy surface local nitriding system provided by the present invention can be used to implement the nitriding method provided by the present invention, and can solve the problems of workpiece deformation and inefficiency caused by long-term high-temperature and high-pressure nitriding.

[0090] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for local nitriding of titanium alloy surface, characterized in that: The method is implemented by using a titanium alloy surface local nitriding device, which includes a laser scanning system, a vacuum box and an air pump. The laser emission direction of the laser scanning system is toward the vacuum box, the vacuum box is connected to the air pump, and the vacuum box is provided with a nitrogen inlet. One side wall of the vacuum box has a transparent area, and an operation port is provided on a side wall opposite to the transparent area. The position of the operation port corresponds to the position of the transparent area. When working, the side of the vacuum box with the operation port is buckled on the surface of the area to be nitrided of the titanium alloy workpiece, and the laser emission direction of the laser scanning system is toward the transparent area. The titanium alloy surface local nitriding device further comprises a sealing member, which is arranged at the edge of the operation port; The local nitriding methods of titanium alloy surface include: Vacuum the surface of the titanium alloy workpiece in the area to be nitrided; The surface of the titanium alloy workpiece in the area to be nitrided is placed in a nitrogen atmosphere; Performing nitriding treatment on the area to be nitrided of the titanium alloy workpiece by using laser scanning; During nitriding treatment, according to the thickness requirement of the nitriding layer, the laser power is 200-6000W, the scanning frequency is 50-1000Hz, and the scanning speed is 200-1000mm / s, so that the surface of the titanium alloy workpiece to be nitrided is melted to form a molten pool.

2. The method for local nitriding of titanium alloy surface according to claim 1, characterized in that: The titanium alloy surface local nitriding device also includes a displacement control mechanism for controlling the distance from the laser scanning system to the operation port, and the displacement control mechanism is connected to the vacuum box and the laser scanning system.

3. The method for local nitriding of titanium alloy surface according to claim 2, characterized in that: The displacement control mechanism includes a motor, a connecting rod and a connecting piece, wherein the connecting piece is connected to the laser scanning system and is provided with an internal thread. The connecting rod is vertically arranged and one end thereof is connected to the motor. The other end surface of the connecting rod is provided with an external thread which extends into the connecting piece and cooperates with the internal thread.

4. The method for local nitriding of titanium alloy surface according to claim 3, characterized in that: The titanium alloy surface local nitriding device also includes a pressure gauge, which is used to test the air pressure in the vacuum box.

5. The method for local nitriding of titanium alloy surface according to claim 1, characterized in that: There are multiple vacuum pumps, and all of the vacuum pumps are connected to the vacuum box.

6. The method for local nitriding of titanium alloy surface according to claim 1, characterized in that: The transparent area is a transparent plate or a lens.

7. The method for local nitriding of titanium alloy surface according to claim 4, characterized in that: The titanium alloy surface local nitriding device also includes a solenoid valve, which is arranged at the nitrogen inlet.

8. The method for local nitriding of titanium alloy surface according to claim 7, characterized in that: The titanium alloy surface local nitriding device also includes a control system, which is communicatively connected with the laser scanning system, the motor, the pressure gauge, the solenoid valve and the vacuum pump.

9. The method for local nitriding of titanium alloy surface according to claim 1, characterized in that: The scan overlap area was 0-0.5 mm.

10. The method for local nitriding of titanium alloy surface according to claim 1, characterized in that: During nitriding treatment, the laser scanning is positively defocused, the distance from the laser head to the surface of the area to be nitrided is within the laser focal length range, and the diameter of the laser spot is less than or equal to 2 mm.

11. The method for local nitriding of titanium alloy surface according to claim 1, characterized in that: Before the nitriding treatment is performed, the surface of the area to be nitrided is cleaned by laser scanning.

12. The method for local nitriding of titanium alloy surface according to claim 11, characterized in that: When cleaning the surface, the laser power is 500-1000W, the scanning frequency is 500-1000Hz, and the scanning speed is 200-1000mm / s.

13. The method for local nitriding of titanium alloy surface according to claim 11, characterized in that: When the vacuum is evacuated to a pressure less than or equal to 100 Pa, the surface of the area to be nitrided is cleaned.

14. The method for local nitriding of titanium alloy surface according to claim 1, characterized in that: The surface of the area to be nitrided of the titanium alloy workpiece is placed in a nitrogen atmosphere, and when the gas pressure reaches 100-1000 Pa, laser scanning is used to perform nitriding treatment on the area to be nitrided of the titanium alloy workpiece.

15. The method for local nitriding of titanium alloy surface according to claim 14, characterized in that: The method of placing the surface of the titanium alloy workpiece in the area to be nitrided in a nitrogen atmosphere is to fill nitrogen into a closed space formed on the surface of the titanium alloy workpiece in the area to be nitrided.

16. The method for local nitriding of titanium alloy surface according to claim 15, characterized in that: While filling with nitrogen, a dilution gas is also introduced into the closed space, and the dilution gas is an inert gas.

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