A heat treatment method and apparatus

Abstract

The present invention relates to the field of heat treatment, and discloses a heat treatment method and apparatus. Among them, the heat treatment method includes the following steps: placing a workpiece to be treated in a closed chamber; injecting a protective gas into the closed chamber to press out the air in the closed chamber; placing the closed chamber in an air furnace; carrying out aging treatment in the air furnace, and during the heating stage of the aging treatment, when the pressure in the closed chamber is greater than a preset pressure, discharging the pressure of the closed chamber outwards. Compared with vacuum or atmosphere heat treatment, using the heat treatment method provided by the present invention for heat treatment has a shorter manufacturing cycle and higher production efficiency.

Description

Technical Field

[0001] The present invention relates to the field of heat treatment, and particularly to a heat treatment method and device. Background Art

[0002] Whether it is a large-thickness titanium alloy component used in aerospace or a titanium alloy thin-walled shell dedicated to the weapon industry, it needs to be completed through advanced manufacturing technologies such as hot forming, precision welding, numerical control machining, or additive manufacturing, and finally achieve precision assembly or welding, and ensure long-term structural and dimensional stability. However, no matter it is hot forming, precision welding, numerical control machining, or additive manufacturing, it will invariably bring residual stress and cause component deformation, seriously affecting the subsequent assembly and service life.

[0003] In order to eliminate or reduce the residual stress and deformation after processing, the traditional aging treatment method is to use vacuum furnace heat treatment or atmosphere furnace to achieve the purpose of isolating air, avoiding air erosion of titanium alloy parts at high temperatures and causing performance degradation. However, both vacuum or atmosphere heat treatment require a long time for vacuum pumping, cooling, and vacuum release, seriously lengthening the manufacturing cycle and reducing production efficiency.

[0004] Therefore, how to shorten the manufacturing cycle and improve production efficiency has become an urgent problem for those skilled in the art. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a heat treatment device and method that can shorten the manufacturing cycle and improve production efficiency.

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

[0007] The present invention provides a heat treatment method, including the following steps:

[0008] Place the workpiece to be processed in a closed chamber;

[0009] Inject a protective gas into the closed chamber to press out the air in the closed chamber;

[0010] Place the closed chamber in an air furnace;

[0011] Carry out aging treatment in the air furnace, and during the heating stage of the aging treatment, when the pressure in the closed chamber is greater than a preset pressure, release the pressure of the closed chamber to the outside.

[0012] Optionally, the closed chamber includes a first cavity and a second cavity arranged in sequence from top to bottom along the height direction of the air furnace. Inject a protective gas into the second cavity to discharge the air in the closed chamber, and place the workpiece to be processed in the first cavity.

[0013] Optionally, the heat treatment method further includes the following steps:

[0014] Fill a plurality of heat-conducting particles between the workpiece to be processed and the inner wall of the closed chamber to limit the deformation of the workpiece to be processed.

[0015] Optionally, the heat treatment method further includes the following steps:

[0016] When the workpiece to be processed has a cavity inside and an opening communicating with the cavity is provided on the outer wall of the workpiece to be processed, fill a plurality of heat-conducting particles into the workpiece to be processed through the opening to limit the deformation of the workpiece to be processed.

[0017] Optionally, there is a gap between the topmost heat-conducting particle and the top of the closed chamber.

[0018] The present invention also provides a heat treatment device for being arranged in an air furnace, including: a housing, a first valve, a second valve, and a pressure relief valve. The inside of the housing is a closed chamber for accommodating a workpiece to be processed. The first valve, the second valve, and the pressure relief valve are all arranged on the housing. The first valve is used to inject a protective gas into the closed chamber, the second valve is used to discharge the air in the closed chamber, and the pressure relief channel is used to relieve the pressure of the closed chamber outward when the pressure in the closed chamber is greater than a preset pressure during the heating stage of the aging treatment.

[0019] Optionally, the inside of the closed chamber has a first partition and a second partition that are oppositely arranged and have a gap therebetween. The first partition and the second partition divide the closed chamber into the first cavity, the homogenizing chamber, and the second cavity in sequence from top to bottom along the height direction of the air furnace. A plurality of first openings are provided on the first partition, and both ends of each first opening communicate with the first cavity and the homogenizing chamber respectively. A plurality of second openings are provided on the second partition, and both ends of each second opening communicate with the homogenizing chamber and the second cavity respectively, and the size of the first opening is smaller than that of the second opening.

[0020] Optionally, the heat treatment device further includes a plurality of heat-conducting particles, and the heat-conducting particles are filled between the workpiece to be processed and the inner wall of the closed chamber to limit the deformation of the workpiece to be processed.

[0021] Optionally, the workpiece to be processed has a cavity inside, and an opening communicating with the cavity is provided on the outer wall of the workpiece to be processed. The heat-conducting particles are filled into the cavity through the opening to limit the deformation of the workpiece to be processed.

[0022] Optionally, there is a spacing between the topmost heat-conducting particles and the top of the closed chamber.

[0023] The present invention achieves the following technical effects compared with the prior art:

[0024] The heat treatment method provided by the present invention isolates the workpiece to be treated from air by injecting a protective gas into the closed chamber and using the protective gas to press out the air in the closed chamber, and performs heat treatment by placing the closed chamber in an air furnace. Compared with vacuum or atmosphere heat treatment for evacuation, cooling, and vacuum release, the heat treatment method provided by the present invention takes less time, is simpler to operate, can effectively shorten the manufacturing cycle, and improve production efficiency. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0026] Figure 1 It is a schematic structural diagram of the heat treatment device provided in the embodiment of the present invention;

[0027] Figure 2 It is a cross-sectional view of the heat treatment device provided in the embodiment of the present invention;

[0028] Figure 3 It is a schematic diagram of the arrangement of the first partition and the second partition of the heat treatment device provided in the embodiment of the present invention;

[0029] Figure 4 It is a schematic structural diagram of the top cover of the heat treatment device provided in the embodiment of the present invention;

[0030] Figure 5 It is a schematic diagram of the arrangement of the workpiece to be treated in the heat treatment device provided in the embodiment of the present invention.

[0031] Figures 1-5 Explanation of the reference numerals in the drawings: 100, heat treatment device; 1, housing; 101, gas storage area; 102, homogenization chamber; 103, gas stagnation area; 2, top cover; 3, first pressure relief valve; 4, first valve; 5, second pressure relief valve; 6, first partition; 601, first opening; 7, second partition; 701, second opening; 8, second valve; 9, workpiece to be treated; 901, cavity; 10, upper particle layer; 11, lower particle layer; 12, top covering layer. Detailed Embodiments

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] The object of the present invention is to provide a heat treatment device and method that can shorten the manufacturing cycle and improve production efficiency.

[0034] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Referring to Figures 1-5 As shown, an embodiment provided by the present invention discloses a heat treatment method, including the following steps: placing a workpiece 9 to be processed in a closed chamber; injecting a protective gas into the closed chamber to press out the air in the closed chamber, and the protective gas, for example, an inert gas is selected, and more specifically, for example, argon; placing the closed chamber in an air furnace; performing aging treatment in the air furnace, and during the heating stage of the aging treatment, when the pressure in the closed chamber is greater than a preset pressure, discharging the closed chamber to the outside.

[0036] Compared with vacuum or atmosphere heat treatment for evacuation, cooling, and vacuum release, the heat treatment method provided by the present invention only needs to use a protective gas to press out the air in the closed chamber. The heat treatment method provided by the present invention takes less time and is simpler to operate, and can effectively shorten the manufacturing cycle and improve production efficiency.

[0037] Specifically, the operator can first place the workpiece 9 to be processed in the closed chamber, then inject the protective gas into the closed chamber, use the protective gas to press out the air in the closed chamber, and then place the closed chamber in the air furnace.

[0038] In some embodiments provided by the present invention, the closed chamber includes a first cavity and a second cavity sequentially arranged from top to bottom along the height direction of the air furnace. Inject the protective gas into the second cavity to discharge the air in the closed chamber, and place the workpiece 9 to be processed in the first cavity. With this arrangement, the second cavity forms a gas storage area 101 to store a certain pressure and quantity of the protective gas. When the temperature rises during the heating stage of the aging treatment, the protective gas in the second cavity rises to continuously provide gas protection for the workpiece 9.

[0039] Further, as Figure 3 shown, the protective gas enters the second cavity after being homogenized. With this arrangement, the protective gas can be evenly dispersed in the second cavity. It should be noted that Figure 3The direction indicated by the arrow is the flow direction of the protective gas.

[0040] In some embodiments provided by the present invention, the heat treatment method further includes the following steps:

[0041] As Figure 2 and Figure 3 shown, a plurality of heat-conducting particles are filled between the workpiece 9 to be processed and the inner wall of the closed chamber to limit the deformation of the workpiece 9 to be processed. Preferably, the heat-conducting particles surround the workpiece 9 to be processed. In addition, it is preferable to select heat-conducting particles that can be blown by the protective gas to limit the deformation of the workpiece 9 to be processed. In this way, when the protective gas passes through the heat-conducting particles, it will push the heat-conducting particles to roll, so that the air between the heat-conducting particles is discharged with the protective gas, and air residue can be avoided.

[0042] The function of the heat-conducting particles is to conduct heat to the workpiece 9 to be processed and keep the workpiece 9 in shape. During the entire heat treatment process, the heat-conducting particles will not deform, and no gas or other substances that affect the heat treatment of the workpiece 9 to be processed will be generated. For example, the material of the heat-conducting particles can be the same as that of the workpiece 9 to be processed.

[0043] Furthermore, the heat treatment method further includes the following steps:

[0044] As Figure 2 and Figure 5 shown, when there is a cavity 901 inside the workpiece 9 to be processed and an opening communicating with the cavity 901 is provided on the outer wall of the workpiece 9 to be processed, a plurality of heat-conducting particles are filled into the workpiece 9 to be processed through the opening to limit the deformation of the workpiece 9 to be processed. Preferably, the cavity 901 is filled with heat-conducting particles. It should be noted that for a solid workpiece 9 to be processed, there is no need to fill heat-conducting particles into the workpiece 9 to be processed, and two or more workpieces 9 to be processed can be placed in the closed chamber at the same time.

[0045] Furthermore, there is a gap between the topmost heat-conducting particle and the top of the closed chamber. With such a setting, a stagnant gas area 103 is formed between the topmost heat-conducting particle and the top of the closed chamber. When the temperature drops at the end of the aging treatment, the stagnant gas area 103 can block the entry of external gas, ensure the concentration of the protective gas inside the closed chamber, and protect the workpiece 9 to be processed from oxidation pollution.

[0046] Refer to Figures 1-5 shown, in the embodiments provided by the present invention, a heat treatment device 100 is also disclosed, which is used to be arranged in an air furnace and includes: a housing 1, a first valve 4, a second valve 8, and a pressure relief valve.

[0047] Specifically, the interior of the housing 1 is a closed chamber for accommodating the workpiece 9 to be processed. The interior of the housing 1 is a closed chamber for accommodating the workpiece 9 to be processed. The first valve 4, the second valve 8 and the pressure relief valve are all arranged on the housing 1. The first valve 4 is used to inject protective gas into the closed chamber, the second valve 8 is used to discharge the air in the closed chamber, and the pressure relief valve is used to relieve the pressure of the closed chamber to the outside when the pressure in the closed chamber is greater than the preset pressure during the heating stage of the aging treatment.

[0048] The pressure relief valve is, for example, a one-way pressure relief valve. When the pressure in the closed chamber is greater than the preset pressure, the one-way pressure relief valve automatically opens and the closed chamber relieves pressure to the outside.

[0049] Furthermore, in order to relieve pressure quickly, the number of pressure relief valves is two or more.

[0050] Even further, as Figure 1 shown, the number of pressure relief valves is two. One of the two pressure relief valves is arranged at the top end of the housing 1, and the other is arranged at the lower end of the housing 1. The pressure relief valve arranged at the lower end of the housing 1 is the first pressure relief valve 3, and the pressure relief valve arranged at the top end of the housing 1 is the second pressure relief valve 5.

[0051] More specifically, as Figure 1 shown, the first valve 4 is arranged at the lower end of the housing 1. In order to avoid residual air in the closed chamber, the first valve 4 should be as close as possible to the bottom end of the housing 1. The second valve 8 is arranged at the top end of the housing 1.

[0052] In some embodiments provided by the present invention, as Figure 2 and Figure 3 shown, the interior of the closed chamber has a first partition 6 and a second partition 7 which are oppositely arranged and have a spacing. The first partition 6 and the second partition 7 divide the closed chamber into a first cavity, a homogenizing chamber 102 and a second cavity in sequence from top to bottom along the height direction of the air furnace. A plurality of first openings 601 are arranged on the first partition 6, and both ends of each first opening 601 communicate with the first cavity and the homogenizing chamber 102 respectively. A plurality of second openings 701 are arranged on the second partition 7, and both ends of each second opening 701 communicate with the homogenizing chamber 102 and the second cavity respectively, and the size of the first opening 601 is smaller than that of the second opening 701. The height of the first cavity is preferably 70 mm to 90 mm larger than the height of the workpiece 9 to be processed, and the width and length are preferably 50 mm to 70 mm larger than the width and length of the workpiece 9 to be processed respectively. When a plurality of workpieces 9 to be processed need to be placed, the spacing between the workpieces 9 to be processed is greater than or equal to 20 mm.

[0053] During the specific use process, as Figure 3As shown, when the protective gas passes through the second opening 701, the first homogenization treatment is performed. When it passes through the first opening 601, the second homogenization treatment is performed. Through the two homogenization treatments, the protective gas can be more evenly distributed in the first cavity. The protective gas has two functions. One is to protect the workpiece 9 to be processed from oxidation, and the other is to conduct heat.

[0054] It should be noted that it is not limited to the method of setting the first partition 6 and the second partition 7 and opening the first opening 601 and the second opening 701 on the first partition 6 and the second partition 7 respectively to achieve gas homogenization. Any structure that can homogenize the protective gas can be used to pre-homogenize the protective gas entering the first cavity. This is just one of the ways.

[0055] In some embodiments provided by the present invention, as Figure 2 and Figure 5 shown, the heat treatment device 100 further includes a plurality of heat-conducting particles. The heat-conducting particles are filled between the workpiece 9 to be processed and the inner wall of the closed chamber to limit the deformation of the workpiece 9 to be processed. Similarly, it is best to surround the workpiece 9 to be processed with the heat-conducting particles. It is best to select heat-conducting particles that can be blown by the protective gas to limit the deformation of the workpiece 9 to be processed. In this way, when the protective gas passes between the heat-conducting particles, it will push the heat-conducting particles to roll, so that the air between the heat-conducting particles is discharged with the protective gas, and air residue can be avoided. The function of the heat-conducting particles is to conduct heat to the workpiece 9 to be processed and keep the workpiece 9 in shape. During the entire heat treatment process, the heat-conducting particles cannot deform, and no gas or other substances that affect the heat treatment of the workpiece 9 can be generated. For example, the material of the heat-conducting particles can be the same as the material of the workpiece 9 to be processed.

[0056] Furthermore, as Figure 5 shown, the workpiece 9 to be processed has a cavity 901 inside. An opening communicating with the cavity 901 is provided on the outer wall of the workpiece 9 to be processed. The heat-conducting particles are filled in the cavity 901 through the opening to limit the deformation of the workpiece 9 to be processed. Similarly, the heat-conducting particles preferably fill the cavity 901. For a solid workpiece 9 to be processed, there is no need to fill heat-conducting particles inside the workpiece 9 to be processed, and two or more workpieces 9 to be processed can be placed in the closed chamber at the same time.

[0057] Further, considering that when the size of the heat-conducting particles is smaller than the communication structure between the first cavity and the second cavity, such as the sizes of the first opening 601 and the second opening 701 in the above embodiments, the heat-conducting particles will fall. A lower particle layer 11 and an upper particle layer 10 are arranged in the first cavity from bottom to top along the height direction of the air furnace. Both the upper particle layer 10 and the lower particle layer 11 are paved with heat-conducting particles. The size of the heat-conducting particles in the lower particle layer 11 is larger than that of the heat-conducting particles in the upper particle layer 10, and the size of the heat-conducting particles in the lower particle layer 11 is larger than the size of the communication structure, so as to ensure that the heat-conducting particles do not fall.

[0058] Further, as Figure 2 and Figure 3 shown, there is a spacing between the topmost heat-conducting particles and the top of the closed chamber. Similarly, by setting it like this, a stagnant gas area 103 is formed between the topmost heat-conducting particles and the top of the closed chamber. When the temperature decreases at the end of the aging treatment, the stagnant gas area 103 can block the entry of external gas, ensure the concentration of the protective gas inside the closed chamber, and protect the workpiece 9 to be processed from oxidation pollution.

[0059] In some embodiments provided by the present invention, in order to facilitate the loading and unloading of the workpiece 9 to be processed, as Figure 1 shown, the top end of the housing 1 is provided with an open mouth, and a top cover 2 is provided at the top end of the housing 1 in an openable manner. For example, the top cover 2 is connected to the top end of the housing 1 by bolts. In the specific use process, by removing the top cover 2, the workpiece 9 to be processed can be placed into the closed chamber, and by setting the top cover 2 at the top end of the housing 1, the top end of the housing 1 can be sealed to realize the sealing of the closed chamber.

[0060] The following takes the aging treatment of a titanium alloy workpiece as an example to introduce in detail the heat treatment device 100 and method provided in the embodiments of the present invention:

[0061] The main component of the titanium alloy material is titanium element, which directly determines the basic properties of the workpiece. Titanium element is very stable at room temperature. When heated to high temperatures, such as during welding and aging treatment, titanium element becomes very active and can have strong chemical reactions with oxygen, hydrogen, nitrogen, carbon dioxide, water vapor, etc. in the atmosphere. At 300°C, titanium starts to rapidly absorb hydrogen, at 600°C it starts to absorb oxygen, and at 700°C it starts to absorb nitrogen, forming a hard and brittle surface layer of non-metallic compounds, which causes a decrease in plasticity, an increase in brittleness, and also a reduction in strength. The depth of the hard and brittle surface layer caused by gas absorption can reach 0.15 mm to 0.25 mm, and the hardening degree exceeds 20% to 30% of the base material, showing a network distribution and forming network cracks that are prone to cracking. The voids on the surface cracks continue to absorb air, triggering new cracks and forming new cracks, continuously increasing the depth of the hard and brittle layer. Therefore, during the hot processing of titanium alloy, it is necessary to use equipment or protective media to isolate air to avoid surface oxidation and other contaminations and protect the titanium alloy workpiece. For example, when aging the titanium alloy workpiece, it is carried out in an internal vacuum furnace or an atmosphere furnace to achieve the purpose of isolating air.

[0062] Aging treatment is to eliminate the residual stress generated during the processing and ensure dimensional stability. Aging treatment is usually adopted after processes such as cold deformation, casting, welding, machining, and additive manufacturing to achieve the effects of eliminating residual stress, improving the plasticity of the workpiece, and stabilizing the structure after processing. The aging treatment temperature of medium-strength titanium alloy is generally 450°C to 650°C, and the aging temperature of low-strength titanium alloy and high-strength and high-toughness titanium alloy is 650°C to 800°C. The cooling method is furnace cooling, and the time required for stress relief annealing depends on the thickness of the workpiece and the magnitude of the residual stress.

[0063] Obviously, the aging treatment temperatures are all within the temperature range where the titanium alloy absorbs harmful gases to form a hard and brittle layer, and appropriate methods must be taken to isolate air. In the embodiments of the present invention, both the heat treatment method and the device use an air furnace for treatment, so it is necessary to find a way to isolate air. For this reason, both the heat treatment device 100 and the heat treatment method provided by the present invention place the workpiece 9 to be treated in a closed chamber that discharges air.

[0064] Specifically, the interior of the housing 1 is a closed chamber. The top of the housing 1 is provided with a top cover 2 that can be opened. The wall thickness of the housing 1 is selected according to the weight of the workpiece 9 to be treated, but it shall not be less than 5 mm. After the workpiece 9 to be treated is loaded and the air in the closed chamber is discharged, the housing 1 is placed in an air furnace for heat treatment.

[0065] Such as Figure 1As shown in the figure, a first valve 4 and a pressure relief valve are provided on one side of the lower end of the housing 1. A first partition 6 and a second partition 7 are installed inside the housing 1. The distance between the second partition 7 and the bottom is 20 mm. A second chamber, namely the gas storage area 101, is formed between the second partition 7 and the bottom end of the closed chamber. The distance between the first partition 6 and the second partition 7 is greater than 5 mm, forming a homogenizing chamber 102. When the pressure inside the second chamber exceeds 0.5 Mpa, the internal gas flows out along the pressure relief valve (4), reducing the pressure inside the closed chamber and playing a role in regulating the internal pressure. The aperture of the second opening 701 is Φ5 mm, the spacing is 20 mm, and the edge distance is 16 mm. The aperture of the first opening 601 is Φ2.5 mm, the spacing is 10 mm, and the edge distance is 20 mm.

[0066] As Figure 1 and Figure 4 shown in the figure, a second valve 8 and a pressure relief valve are provided on the top cover 2. When the working pressure of the first cavity exceeds 0.2 MPa, the pressure relief valve on the top cover 2 opens to start pressure relief, ensuring that the pressure inside the first cavity does not exceed 0.2 MPa. After the heat treatment is completed, open the second valve 8 of the top cover 2 to connect the first cavity with the atmosphere and release the internal pressure.

[0067] Argon is filled into the second cavity through the first valve 4 to fill the protective gas in the second cavity. The protective gas overflows through the second air hole to form a homogenized protective gas flow, and the protective gas undergoes the first homogenization treatment. Subsequently, the protective gas continues to pass through the first air hole to form a refined protective gas flow, and the second homogenized protective gas enters the first cavity.

[0068] While homogenizing the protective gas, the workpiece 9 to be processed is loaded into the first cavity. First, a lower particle layer 11 is laid at the bottom of the first cavity. The laying thickness of the lower particle layer 11 is 10 mm. The diameter of the titanium alloy heat-conducting particles in the lower particle layer 11 is between Φ2.5 mm and Φ3.0 mm. The titanium alloy heat-conducting particles in the lower particle layer 11 can further refine the protective gas, and the protective gas continues to flow upward through the gaps between the titanium alloy heat-conducting particles in the lower particle layer 11. When laying the titanium alloy heat-conducting particles, it is necessary to slowly stir the titanium alloy heat-conducting particles to discharge the air between the titanium alloy heat-conducting particles. Secondly, after the lower particle layer 11 is laid, the workpiece 9 to be heat-treated is placed on the lower particle layer 11. When the number of workpieces 9 to be processed is multiple, ensure that the spacing between the workpieces 9 to be processed is not less than 20 mm, and the distance between the workpiece 9 to be processed and the inner wall of the first cavity is not less than 20 mm.

[0069] After the workpiece 9 to be processed is placed, an upper particle layer 10 is laid. During the laying process of the upper particle layer 10, the protective gas still needs to be filled. The diameter of the titanium alloy heat-conducting particles in the upper particle layer 10 is between Φ1.5 mm and Φ2.0 mm, and the filling height of the upper particle layer 10 is the same as the height of the workpiece 9 to be processed.

[0070] After completing the loading, covering, and filling of the workpiece 9 to be processed, continue to load titanium alloy heat-conducting particles into the first cavity and fill it with a protective gas to form a top covering layer 12 on the upper part of the workpiece 9 to be processed. The thickness of the top covering layer 12 shall not be less than 10 mm, and the diameter of the titanium alloy heat-conducting particles in the top covering layer 12 is between Φ0.8 mm and Φ1.0 mm. In order to ensure the retention space for the protective gas in the later stage, the height of the space reserved above the top covering layer 12 shall not be less than 5 mm to form a gas-retention area 103.

[0071] During the above loading process, continuously fill the first cavity with the protective gas to ensure that the protective gas fills the surrounding of the workpiece 9 to be processed. Finally, use the top cover 2 to cover and seal the first cavity, and ensure that part of the protective gas flows out from the pressure relief valve of the top cover 2. Subsequently, adjust the threshold pressure of the pressure relief valve on the top cover 2 to 0.2 MPa, close the first valve 4, and cut off the initial protective gas flow.

[0072] After completing the overall protection, place the closed chamber loaded with the workpiece 9 to be processed into an air furnace with a suitable temperature to complete processes such as heating up, heat preservation, and cooling down. During the heating-up process, the gas volume in the closed chamber expands and the pressure rises, and pressure is released outward through two pressure relief valves to ensure safety. During the heat preservation process, the internal and external pressures are balanced and the closed chamber works normally. When the heat treatment furnace cools down, all external outlets are completely closed to block the entry of air, ensuring that the workpiece 9 to be processed in the closed chamber continues to be in a protective atmosphere and is not damaged.

[0073] After completing the heat treatment and when the temperature drops to room temperature, take out the closed chamber from the air furnace. At the same time, open the first valve 4 and the second valve 8 on the top cover 2 to connect to the atmosphere from the upper and lower directions to release the residual pressure and gas inside. Finally, open the top cover 2, clean the titanium alloy heat-conducting particles, and take out the workpieces 9 to be processed one by one.

[0074] When the workpiece 9 to be processed is heat-treated by using the heat-treatment method and the heat-treatment device 100 provided in this embodiment, not only can the heat-treatment effect of an air furnace be achieved, but more importantly, by filling an appropriate material in the chamber to be processed, the purpose of shape retention can be achieved, eliminating the design and manufacturing processes of shape retention and straightening tooling, saving costs and cycle time. In addition, the heat-treatment method and the heat-treatment device 100 provided in this embodiment are not only applicable to the stress-relieving aging treatment of small parts, but can also be extended to the heat treatment of other titanium alloy workpieces with extremely large sizes and complex shapes in aircraft manufacturing. Different closed chambers can be fabricated according to the shape, structure, and size of the workpiece to be processed, and the work of a vacuum furnace or an atmosphere furnace can be completed in an air furnace, simplifying the manufacturing process, improving work efficiency, and reducing manufacturing costs. At the same time, the medium material (titanium alloy heat-conducting particles) can be replaced with other metals or sand, and the protective gas can be changed from argon to other inert gases, such as nitrogen used at low temperatures or helium used at higher temperatures, which can not only improve the heating efficiency but also greatly improve the protection effect.

[0075] It should be noted that the heat-treatment method and the heat-treatment device 100 provided by the present invention are not only applicable to the heat treatment of titanium alloy workpieces, but also applicable to the heat treatment of workpieces made of other metal materials.

[0076] Specific examples are used in this specification to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A heat treatment method, characterized in that, The method includes the following steps: placing a workpiece to be processed in a closed chamber; injecting a protective gas into the closed chamber to press out the air in the closed chamber; placing the closed chamber in an air furnace; performing aging treatment in the air furnace, and during the heating stage of the aging treatment, when the pressure in the closed chamber is greater than a preset pressure, relieving the pressure of the closed chamber outwards; filling a plurality of heat-conducting particles between the workpiece to be processed and the inner wall of the closed chamber to limit the deformation of the workpiece to be processed; the heat-conducting particles can be blown by the protective gas; the closed chamber has a first partition plate and a second partition plate which are oppositely arranged and have a spacing therebetween, and the first partition plate and the second partition plate divide the closed chamber into a first cavity, a homogenization chamber and a second cavity in sequence from top to bottom along the height direction of the air furnace, the first partition plate is provided with a plurality of first openings, both ends of each first opening communicate with the first cavity and the homogenization chamber respectively, the second partition plate is provided with a plurality of second openings, both ends of each second opening communicate with the homogenization chamber and the second cavity respectively; a lower particle layer and an upper particle layer are arranged in the first cavity from bottom to top along the height direction of the air furnace, both the upper particle layer and the lower particle layer are paved by the heat-conducting particles, the size of the heat-conducting particles in the lower particle layer is larger than the size of the heat-conducting particles in the upper particle layer, and the size of the heat-conducting particles in the lower particle layer is larger than the sizes of the first openings and the second openings; injecting the protective gas into the second cavity to discharge the air in the closed chamber, and placing the workpiece to be processed in the first cavity.

2. The heat treatment method according to claim 1, wherein The method further includes the following steps: when the workpiece to be processed has a cavity inside and an opening communicating with the cavity is provided on the outer wall of the workpiece to be processed, filling a plurality of heat-conducting particles into the workpiece to be processed through the opening to limit the deformation of the workpiece to be processed.

3. The heat treatment method according to claim 1, wherein There is a spacing between the topmost heat-conducting particle and the top of the closed chamber.

4. A heat treatment device, characterized in that, For being set inside an air furnace, it includes: a housing, a first valve, a second valve and a pressure relief valve. The interior of the housing is a closed chamber for accommodating the workpiece to be processed. The first valve, the second valve and the pressure relief valve are all arranged on the housing. The first valve is used to inject a protective gas into the closed chamber. The second valve is used to discharge the air in the closed chamber. The pressure relief valve is used to relieve the pressure of the closed chamber to the outside when the pressure in the closed chamber is greater than a preset pressure during the heating stage of the aging treatment. It also includes a plurality of heat-conducting particles filled between the workpiece to be processed and the inner wall of the closed chamber to limit the deformation of the workpiece to be processed. The heat-conducting particles can be blown by the protective gas. Inside the closed chamber, there are a first partition and a second partition which are oppositely arranged with a spacing. The first partition and the second partition divide the closed chamber into a first cavity, a homogenizing chamber and a second cavity in sequence from top to bottom along the height direction of the air furnace. A plurality of first openings are arranged on the first partition, and both ends of each first opening communicate with the first cavity and the homogenizing chamber respectively. A plurality of second openings are arranged on the second partition, and both ends of each second opening communicate with the homogenizing chamber and the second cavity respectively. In the first cavity, a lower particle layer and an upper particle layer are arranged from bottom to top along the height direction of the air furnace. Both the upper particle layer and the lower particle layer are formed by laying the heat-conducting particles. The size of the heat-conducting particles in the lower particle layer is larger than that of the heat-conducting particles in the upper particle layer, and the size of the heat-conducting particles in the lower particle layer is larger than the sizes of the first openings and the second openings.

5. The heat treatment apparatus according to claim 4, wherein The interior of the workpiece to be processed has a cavity, and an opening communicating with the cavity is arranged on the outer wall of the workpiece to be processed. The heat-conducting particles are filled into the cavity through the opening to limit the deformation of the workpiece to be processed.

6. The heat treatment apparatus according to claim 4, characterized in that, There is a spacing between the heat-conducting particle at the topmost and the top of the closed chamber.

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