Method for preparing titanium alloy pipe fitting by utilizing recycled coarse powder at low cost

Abstract

The invention belongs to the technical field of preparation of titanium alloy pipe fittings from recycled coarse powder, and particularly relates to a low-cost method for preparing titanium alloy pipe fittings from recycled coarse powder, which comprises the following steps: firstly, recycling titanium alloy coarse powder with the particle size of more than 100 mu m, then exposing a fresh titanium surface through hydrogenation fragmentation by utilizing a hydrogenation dehydrogenation (HDH) technology, adsorbing oxygen in the atmosphere, and diffusing for solid solution; the O content of the powder is increased; interstitial O atoms can be subjected to pinning dislocation, so that the yield strength, tensile strength and hardness of sintered parts are remarkably improved, and low cost and high performance are realized (namely, the O content of powder is improved through HDH, and a basis is provided for good performance of subsequent parts); according to the preparation method, coarse powder with low utilization rate is recycled through a set of complete preparation process, the cost for preparing the titanium alloy pipe fitting is reduced, and meanwhile, the performance of the titanium alloy pipe fitting is improved.

Description

Technical Field

[0001] This invention belongs to the technical field of preparing titanium alloy pipe fittings from recycled coarse powder, and specifically relates to a method for preparing titanium alloy pipe fittings from recycled coarse powder at low cost. Background Technology

[0002] During powder preparation and use, a significant amount of coarse powder is generated (accounting for 20% to 50% of the original powder). Due to its small specific surface area, low total oxide interface, and low oxygen content, and because oxygen, as an interstitial strengthening element, plays a significant strengthening role in titanium alloys, the utilization rate of this coarse powder is low. If this coarse powder cannot be effectively recycled, it will result in the waste of precious metals.

[0003] With the development of my country's aerospace industry, the demand for titanium alloy tubing is increasing. Current technologies primarily employ extrusion and rolling processes for production. However, titanium alloys have high deformation resistance, and the quality fluctuations resulting from these conventional processes severely impact the fatigue life of the tubing, making it difficult to meet the development goals of lightweight, high-performance, and long-life advanced aircraft.

[0004] To address the shortcomings of conventional processes, researchers have begun using simultaneous heating and pressurization hot isostatic pressing (HIP) technology to prepare titanium alloy tubular components. This technology simultaneously completes forming and sintering, eliminates internal defects, improves isotropy, and significantly enhances the fatigue resistance of the material under cyclic loading. It is particularly suitable for manufacturing complex-shaped titanium alloy parts.

[0005] However, simultaneous heating and pressurization, which applies pressure at low temperatures, makes it difficult for the powder to undergo sufficient plastic deformation and diffusion healing, easily leaving high porosity and PPB defects, thus requiring higher equipment pressure and a narrow process window.

[0006] Furthermore, the high cost of hot isostatic pressing (HIP) components limits their use to high-value-added fields. The costs of powder preparation, cladding fabrication, and powder loading / degassing account for approximately 70% of the total cost. Moreover, during HIP, the steel cladding used undergoes irreversible physical and chemical degradation due to plastic deformation, microstructural phase changes, or surface contamination after exposure to high temperature and pressure. This results in dimensional accuracy and mechanical strength failing to meet the technical requirements for reuse. This non-reusability significantly increases the material cost and resource consumption per processing cycle, while also extending the production cycle due to the need for frequent cladding replacements.

[0007] In view of this, the present invention is hereby proposed. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and propose a method for preparing titanium alloy pipe fittings at low cost using recycled coarse powder.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for low-cost preparation of titanium alloy pipe fittings using recycled coarse powder, comprising the following steps (see...). Figure 1 ): Step 1: Customize a cold isostatic pressing mold according to the dimensions of the target titanium alloy pipe fitting; Step 2: Recover titanium alloy powder with a particle size > 100 μm; Step 3: The titanium alloy powder from Step 2 is processed by hydrogenation and dehydrogenation to obtain titanium alloy angular powder with an O content of 0.15%~0.20% and a particle size of 5~50μm. Step 4: The titanium alloy angular powder obtained in Step 3 is loaded into the shaping mold in Step 1, compacted with external force to the set density, sealed, and then subjected to cold isostatic pressing. Step 5: After cold isostatic pressing, remove the shaping mold to obtain the cold isostatic pressed billet; Step 6: Perform hot isostatic pressing on the cold isostatic billet obtained in step 5 to obtain a hot isostatic pressed part; Step 7: Machin the hot isostatic pressing part obtained in step 6 to obtain the target titanium alloy pipe fitting.

[0010] Further, in step 1, the shaping mold includes a rubber top cover, a rubber inner sleeve, a metal shaping outer sleeve, and a steel core. The inner bottom of the rubber inner sleeve has a groove for inserting the bottom end of the steel core. The top of the rubber inner sleeve is covered with a rubber top cover, and the inner bottom of the rubber top cover has a groove for inserting the top end of the steel core. The outer periphery of the rubber inner sleeve is covered with a metal shaping outer sleeve, and the top end of the metal shaping outer sleeve contacts the bottom end of the rubber top cover (forming a sealing structure). The outer periphery of the metal shaping outer sleeve has pressure transmission holes.

[0011] Furthermore, in step 2, the oxygen content of the titanium alloy powder is 0.03%~0.09%.

[0012] Furthermore, in step 4, the set density is 50%~70%.

[0013] Furthermore, in step 4, the pressure during the cold isostatic pressing process is set to 150MPa~300MPa and the time is 1min~20min.

[0014] Furthermore, in step 5, the density of the cold isostatic pressed billet is 60%~80%.

[0015] Furthermore, in step 6, the density of the hot isostatic pressed component is 99%~100%.

[0016] Furthermore, in step 6, during the hot isostatic pressing process, the hot isostatic press is first evacuated to 10...-3 Below Pa, the temperature is increased to 800℃~1000℃ at a heating rate of 5℃ / min~15℃ / min, and held for 2h~4h. Then, argon gas is introduced to increase the pressure to 100MPa~150MPa, and the temperature and pressure are maintained for 1h~3h. Finally, the furnace is cooled and removed from the furnace at the set cooling rate.

[0017] Furthermore, the temperature is lowered to 50℃~200℃ at a cooling rate of 3℃ / min~15℃ / min before being removed from the furnace.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention is an innovative coarse powder recycling method developed in response to the low utilization rate of coarse powder in the production process, and uses the recycled coarse powder to prepare titanium alloy pipe fittings through an innovative low-cost preparation process.

[0019] Specifically, this invention first recovers titanium alloy coarse powder with a particle size greater than 100 μm, and then uses hydrogenation dehydrogenation (HDH) technology to expose fresh titanium surfaces through hydrogenation crushing, adsorbing oxygen in the atmosphere and diffusing solid solution, thereby increasing the O content of the powder. The interstitial O atoms can pin dislocations, significantly improving the yield strength, tensile strength and hardness of the sintered parts, achieving low cost and high performance (i.e., increasing the O content of the powder through HDH, providing a foundation for the good performance of subsequent parts). Then, cold isostatic pressing is used for shaping, followed by hot isostatic pressing with a temperature increase followed by a pressure increase after shaping. This complete preparation process recovers the low-utilization coarse powder, reduces the cost of preparing titanium alloy pipes, and improves the performance of titanium alloy pipes.

[0020] (2) The method of the present invention directly performs hot isostatic pressing on the blank after cold isostatic pressing. Unlike the traditional process (vacuum sintering after cold isostatic pressing + simultaneous heating and pressurization hot isostatic pressing), the present invention eliminates vacuum sintering. The hot isostatic pressing is performed by heating first and then pressurizing. During the heating stage, the powder undergoes slight expansion and diffusion bonding, causing the pores to close prematurely. Then the pressure is increased. At this time, the yield strength of the powder has decreased, making it more prone to large plastic deformation or even "tearing". The same degree of densification can be obtained with lower pressure, which is equivalent to the powder undergoing a "micro-forging". This process can reduce the consumption of high-pressure gas and eliminate PPB and pores. The material further shrinks to be completely dense and pore-free.

[0021] Specifically, cold isostatic pressing simply compresses powder into a green body at room temperature and high pressure, leaving a large number of closed pores and adsorbed gases inside, resulting in a low density. In traditional vacuum sintering, the gas inside the closed pores diffuses rapidly outward under low pressure, allowing the green body to continue shrinking, ultimately achieving a relative density of over 98%. Otherwise, during the subsequent simultaneous heating and pressurization hot isostatic pressing process, the gas trapped inside the green body cannot escape and expands during heating, hindering shrinkage and causing bubbling and cracking, making it difficult to increase density. During the simultaneous heating and pressurization stage, due to the lower temperature and higher yield strength of the part, its deformation capacity is weak, making it difficult to fully break down and eliminate PPB (polyphenol precipitate).

[0022] The hot isostatic pressing (HIP) process, which involves heating first and then pressurizing, allows the part to be heated in a low-vacuum environment. This rapidly diffuses the gas trapped in the closed pores of the green body, causing it to shrink and achieve a density similar to that of vacuum sintering. The high temperature after heating reduces the yield strength of the part, making it more susceptible to large plastic deformation during the subsequent pressurization stage. This process breaks down the PPB (polypropylene oxide) structure, optimizes the microstructure, and further shrinks the material until it becomes completely dense and non-porous.

[0023] (3) The present invention innovatively designs a customized sleeve for cold isostatic pressing. The sleeve is low in cost and reusable. The included metal shape control outer sleeve can effectively control the shape of the rubber sleeve after powder filling, solving the problem of poor powder filling shape control caused by the low hardness of the rubber material in the existing sleeve during the powder filling process. Attached Figure Description

[0024] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a flowchart of the method for preparing titanium alloy pipe fittings at low cost using recycled coarse powder according to the present invention; Figure 2 This is a shaping mold for cold isostatic pressing according to the present invention; Figure 3 The crude TC4 powder recovered in Example 1; Figure 4 Small-particle-size TC4 titanium alloy angular powder prepared by the hydrogenation-dehydrogenation process in Example 1; Figure 5 The TA15 coarse powder recovered in Example 2; Figure 6Small-particle-size TA15 titanium alloy angular powder prepared by the hydrogenation-dehydrogenation process in Example 2; Figure 7 The crude TC18 powder recovered in Example 3; Figure 8 Small-particle-size TC18 titanium alloy angular powder prepared by the hydrogenation-dehydrogenation process in Example 3; Among them, 1 is the rubber top cover; 2 is the rubber inner sleeve; 3 is the metal shape control outer sleeve; 4 is the steel core; and 5 is the pressure transmission hole. Detailed Implementation

[0027] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0028] Please see Figure 2 In the following embodiments 1-3, the shaping mold used includes a rubber top cover 1, a rubber inner sleeve 2, a metal shaping outer sleeve 3, and a steel core 4. The inner bottom of the rubber inner sleeve 2 has a groove for inserting the bottom end of the steel core 4. The top of the rubber inner sleeve 2 is covered by the rubber top cover 1, and the inner bottom of the rubber top cover 1 has a groove for inserting the top end of the steel core 4. The outer periphery of the rubber inner sleeve 2 is covered by the metal shaping outer sleeve 3, and the top end of the metal shaping outer sleeve 3 contacts the bottom end of the rubber top cover 1. The outer periphery of the metal shaping outer sleeve 3 has a pressure transmission hole 5. The grooves of the rubber inner sleeve 2 and the rubber top cover 1 are both located in the central area, used to insert and position the steel core 4 so that it is located in the center of the rubber inner sleeve 2.

[0029] Example 1: Preparation of TC4 titanium alloy pipe fittings This embodiment provides a method for low-cost preparation of TC4 titanium alloy pipe fittings using recycled coarse powder, including the following steps: Step 1: Customize a cold isostatic pressing mold according to the target TC4 titanium alloy pipe fitting dimensions; Step 2: Recover TC4 titanium alloy spherical powder (e.g., with an O content of 0.05%~0.07% and a particle size of 106~250μm) prepared by atomization. Figure 3 ); Step 3: Load the TC4 titanium alloy spherical powder recovered in Step 2 into the hydrogenation furnace, evacuate to below 0.1 Pa, introduce high-purity hydrogen, control the hydrogen pressure in the furnace to 0.5 MPa, heat to 600℃, and hold for 4 hours to allow the titanium alloy to fully absorb hydrogen and become embrittled.

[0030] Step 4: Feed the titanium hydride powder into a fluidized bed jet mill and perform jet milling under a pressure of 0.9 MPa. The separator speed is controlled at 10,000 rpm. Grinding produces small-particle-size TC4 titanium alloy angular powder with an O content of 0.15%~0.20% and a particle size of 10~50 μm (e.g., Figure 4 ); Step 5: Dehydrogenation treatment of titanium hydride alloy powder is carried out in a vacuum furnace, and the vacuum is evacuated to less than 5×10⁻⁻⁻⁶. 3 Pa, slowly heat to 800℃ and hold for 2 hours to decompose titanium hydride powder into titanium alloy powder and hydrogen gas, thus completing the dehydrogenation process.

[0031] Step 6: Place the steel core 4 in the middle of the rubber inner sleeve 2, and nest the metal shaping outer sleeve 3 on the outside of the rubber inner sleeve 2; Step 7: After dehydrogenation in step 5, the titanium alloy angular powder is loaded into the package assembled in step 6 and compacted by external force. After compaction, the density is 50%. The rubber top cover 1 is placed and fixed and sealed with metal clamps. Step 8: The assembly obtained in Step 7 is subjected to cold isostatic pressing at 250 MPa for 3 minutes, and then the mold parts are removed to obtain a cold isostatic pressed blank with a density of 60%.

[0032] Step 9: Perform hot isostatic pressing on the cold isostatic pressing billet obtained in step 8 to obtain a hot isostatic pressed part with a density of 99.7%. The hot isostatic pressing process is as follows: first, the hot isostatic press is evacuated to 10°C. -3 Pa, heated to 960℃ at a heating rate of 15℃ / min and held for 2 hours, then argon gas was introduced and pressurized to 100MPa, and held at the temperature and pressure for 3 hours for hot isostatic pressing; finally, the temperature was lowered to 100℃ at a cooling rate of 5℃ / min before being removed from the furnace.

[0033] Step 10: Machining the hot isostatic pressing part to obtain TC4 titanium alloy pipe fittings.

[0034] Example 2: Preparation of TA15 titanium alloy pipe fittings Step 1: Customize a cold isostatic pressing mold according to the dimensions of the target TA15 titanium alloy pipe fitting; Step 2: Recover TA15 titanium alloy spherical powder (e.g., with an O content of 0.03~0.05% and a particle size of 106~150μm) prepared by atomization. Figure 5 ); Step 3: Load the TA15 titanium alloy spherical powder recovered in Step 2 into a hydrogenation furnace, evacuate to below 0.1 Pa, introduce high-purity hydrogen, control the hydrogen pressure in the furnace to 0.6 MPa, heat to 700℃, and hold for 3 hours to allow the titanium alloy to fully absorb hydrogen and become embrittled.

[0035] Step 4: Feed the titanium hydride powder into a fluidized bed jet mill and perform jet milling under a pressure of 0.8 MPa. The separator speed is controlled at 8000 rpm. Grinding produces small-particle-size TA15 titanium alloy angular powder with an O content of 0.17~0.20% and a particle size of 15~45 μm (e.g., Figure 6 ); Step 5: Dehydrogenation treatment of titanium hydride alloy powder is carried out in a vacuum furnace, and the vacuum is evacuated to less than 5×10⁻⁻⁻⁶. 3 Pa, slowly heat to 800℃ and maintain for 3 hours to decompose titanium hydride powder into titanium alloy powder and hydrogen gas, thus completing the dehydrogenation process.

[0036] Step 6: Place the steel core 4 in the middle of the rubber inner sleeve 2, and nest the metal shaping outer sleeve 3 on the outside of the rubber inner sleeve 2; Step 7: After dehydrogenation in step 5, the titanium alloy angular powder is loaded into the package assembled in step 6 and compacted by external force. After compaction, the density is 67%. The rubber top cover 1 is placed and fixed and sealed with metal clamps. Step 8: The assembly obtained in Step 7 is subjected to cold isostatic pressing at 150 MPa for 20 min, and then the mold parts are removed to obtain a cold isostatic pressed blank with a density of 79%.

[0037] Step 9: Perform hot isostatic pressing on the cold isostatic billet obtained in step 8 to obtain a hot isostatic pressed part with a density of 99.8%. The hot isostatic pressing process is as follows: First, the hot isostatic press is evacuated to 10°C. -3 Pa is heated to 950℃ at a heating rate of 10℃ / min and held for 3 hours. Then, argon gas is introduced to pressurize to 130MPa and held at the temperature and pressure for 2 hours for hot isostatic pressing. Finally, the temperature is cooled to 50℃ at a cooling rate of 15℃ / min before being removed from the furnace.

[0038] Step 10: Machining the hot isostatic pressed parts to obtain TA15 titanium alloy pipe fittings.

[0039] Example 3: Preparation of TC18 titanium alloy pipe fittings Step 1: Customize a cold isostatic pressing mold according to the dimensions of the target TC18 titanium alloy pipe fitting; Step 2: Recover TC18 titanium alloy spherical powder (e.g., with an O content of 0.04-0.09% and a particle size of 150-250 μm) prepared by atomization. Figure 7 ); Step 3: Load the TC18 titanium alloy spherical powder recovered in Step 2 into a hydrogenation furnace, evacuate to below 0.1 Pa, introduce high-purity hydrogen, control the hydrogen pressure in the furnace to 0.5 MPa, heat to 500℃, and hold for 6 hours to allow the titanium alloy to fully absorb hydrogen and become embrittled.

[0040] Step 4: Feed the titanium hydride powder into a fluidized bed jet mill and perform jet milling under a pressure of 0.5 MPa. The separator speed is controlled at 9000 rpm. Grinding produces small-particle-size TC18 titanium alloy angular powder with an O content of 0.16~0.18% and a particle size of 5~50 μm (e.g., Figure 8 ); Step 5: Dehydrogenation treatment of titanium hydride alloy powder is carried out in a vacuum furnace, and the vacuum is evacuated to less than 5×10⁻⁻⁻⁶. 3 Pa, slowly heat to 750℃ and maintain for 4 hours to decompose titanium hydride powder into TC18 titanium alloy powder and hydrogen gas, thus completing the dehydrogenation process.

[0041] Step 6: Place the steel core 4 in the middle of the rubber inner sleeve 2, and nest the metal shaping outer sleeve 3 on the outside of the rubber inner sleeve 2; Step 7: After dehydrogenation in step 5, the titanium alloy angular powder is loaded into the package assembled in step 6 and compacted by external force. After compaction, the density is 60%. A rubber top cover is placed and fixed and sealed with metal clamps. Step 8: The assembly obtained in Step 7 is subjected to cold isostatic pressing at 300 MPa for 5 minutes, and then the mold parts are removed to obtain a cold isostatic pressed blank with a density of 76%.

[0042] Step 9: Perform hot isostatic pressing on the cold isostatic pressing blank obtained in step 8 to obtain a hot isostatic pressed part with a density of 99.5%. The hot isostatic pressing process is as follows: first, the hot isostatic press is evacuated to 10°C. -3 Pa is heated to 800℃ at a heating rate of 5℃ / min and held for 4 hours. Then, argon gas is introduced to pressurize to 150MPa and held at the temperature and pressure for 1 hour for hot isostatic pressing. Finally, the temperature is cooled to 200℃ at a cooling rate of 3℃ / min before being removed from the furnace.

[0043] Step 10: Machining the hot isostatic pressed parts to obtain TC18 titanium alloy pipe fittings.

[0044] It should be added that if the target titanium alloy pipes in Examples 1 to 3 are the same size, then one set of molds can be used.

[0045] Comparative Example 1: Preparation of TC4 titanium alloy pipe fittings Step 1: Prepare TC4 titanium alloy powder with an O content of 0.13~0.18% and a particle size in the range of 15μm~53μm by atomization method; Step 2: Vibrate the TC4 titanium alloy powder prepared in Step 1 into a steel liner. The density of the powder after loading is 68%. Step 3: Degas and seal the powder-filled packaging. Step 4: Perform hot isostatic pressing (HIP) on the sealed sleeve from Step 3. The specific process of HIP is as follows: simultaneously heat up to 960°C at a rate of 10°C / min and pressurize to 150MPa, and hold the temperature and pressure for 3 hours; then cool down to 100°C at a rate of 10°C / min before removing from the furnace.

[0046] Step 5: Remove the outer sheath of the part by machining to obtain TC4 titanium alloy pipe fitting.

[0047] Comparative Example 2: Preparation of TC4 titanium alloy pipe fittings Step 1: Customize a cold isostatic pressing mold according to the target TC4 titanium alloy pipe fitting dimensions; Step 2: Recover TC4 titanium alloy spherical powder with an O content of 0.05~0.08% and a particle size of 120~150μm prepared by atomization; Step 3: Load the TC4 titanium alloy spherical powder recovered in Step 2 into a hydrogenation furnace, evacuate to below 0.1 Pa, introduce high-purity hydrogen, control the hydrogen pressure in the furnace to 0.6 MPa, heat to 600℃, and hold for 4 hours to allow the titanium alloy to fully absorb hydrogen and become embrittled.

[0048] Step 4: Feed the titanium hydride powder into a fluidized bed air jet mill and perform air jet milling under a pressure of 0.7 MPa. The speed of the separator is controlled at 6000 rpm. The grinding produces small-particle-size TC4 titanium alloy angular powder with an O content of 0.17%~0.20% and a particle size of 10~50 μm. Step 5: Dehydrogenation treatment of titanium hydride alloy powder is carried out in a vacuum furnace, and the vacuum is evacuated to less than 5×10⁻⁻⁻⁶. 3 Pa, slowly heat to 700℃ and hold for 3 hours to decompose titanium hydride powder into TC4 titanium alloy powder and hydrogen gas, thus completing the dehydrogenation process.

[0049] Step 6: Place the steel core 4 in the middle of the rubber inner sleeve 2, and nest the metal shaping outer sleeve 3 on the outside of the rubber inner sleeve 2; Step 7: The TC4 titanium alloy powder obtained after dehydrogenation in Step 5 is packed into a rubber sleeve for cold isostatic pressing. The density of the powder after packing is 60%. Step 8: After loading the powder in Step 7, perform cold isostatic pressing at 250 MPa for 3 minutes, and then remove the rubber sleeve to obtain the cold isostatic pressed blank. Step 9: Vacuum sinter the cold isostatic pressed billet obtained in Step 8 at 1200℃ for 2 hours; Step 10: Perform hot isostatic pressing on the billet obtained in step 9 to obtain a hot isostatic pressed part; The specific process of hot isostatic pressing is as follows: the temperature and pressure are simultaneously increased to 960℃ and 150MPa at a heating rate of 15℃ / min, and the temperature and pressure are maintained for 3 hours for hot isostatic pressing; finally, the temperature is reduced to 100℃ at a cooling rate of 5℃ / min and then removed from the furnace to obtain the hot isostatic pressed part. Step 11: Machin the hot isostatic pressing part to obtain TC4 titanium alloy pipe fitting.

[0050] To better illustrate the beneficial effects of the present invention (low cost + high performance), the cost and performance of the titanium alloy pipe fittings prepared in Examples 1-3 and Comparative Examples 1-2 were summarized and compared, and the results are shown in Tables 1 and 2, respectively: Table 1. Cost comparison of pipe fittings prepared in Examples 1-3 and Comparative Examples 1-2 Table 2. Performance comparison results of pipe fittings prepared in Examples 1-3 and Comparative Examples 1-2 This invention enables the recycling of low-oxygen coarse powder and the reuse of the sheath, significantly reducing the manufacturing cost of titanium alloy pipe fittings. As shown in Table 1, the manufacturing cost of this application is lower than that of Comparative Example 1, and the rubber sheath can be reused, resulting in a higher cost-effectiveness in the long run. Furthermore, compared to Comparative Example 2, the manufacturing process reduces vacuum sintering, optimizing both cost and process steps. As shown in Table 2, the pipe fittings prepared in this application exhibit better performance than those prepared in Comparative Example 2, demonstrating significant potential for widespread application.

[0051] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0052] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for low-cost preparation of titanium alloy pipe fittings using recycled coarse powder, characterized in that, Includes the following steps: Step 1: Customize a cold isostatic pressing mold according to the dimensions of the target titanium alloy pipe fitting; Step 2: Recover titanium alloy powder with a particle size > 100 μm; Step 3: The titanium alloy powder from Step 2 is processed by hydrogenation and dehydrogenation to obtain titanium alloy angular powder with an O content of 0.15%~0.20% and a particle size of 5~50μm. Step 4: The titanium alloy angular powder obtained in Step 3 is loaded into the shaping mold in Step 1, compacted with external force to the set density, sealed, and then subjected to cold isostatic pressing. Step 5: After cold isostatic pressing, remove the shaping mold to obtain the cold isostatic pressed billet; Step 6: Perform hot isostatic pressing on the cold isostatic billet obtained in step 5 to obtain a hot isostatic pressed part; Step 7: Machin the hot isostatic pressing part obtained in step 6 to obtain the target titanium alloy pipe fitting.

2. The method for low-cost preparation of titanium alloy pipe fittings using recycled coarse powder according to claim 1, characterized in that, In step 1, the shaping mold includes a rubber top cover (1), a rubber inner sleeve (2), a metal shaping outer sleeve (3), and a steel core (4). The inner bottom of the rubber inner sleeve (2) has a groove for inserting the bottom end of the steel core (4). The top of the rubber inner sleeve (2) is covered with a rubber top cover (1), and the inner bottom of the rubber top cover (1) has a groove for inserting the top end of the steel core (4). The outer periphery of the rubber inner sleeve (2) is covered with a metal shaping outer sleeve (3), and the top end of the metal shaping outer sleeve (3) contacts the bottom end of the rubber top cover (1). The outer periphery of the metal shaping outer sleeve (3) has a pressure transmission hole (5).

3. The method for low-cost preparation of titanium alloy pipe fittings using recycled coarse powder according to claim 1, characterized in that, In step 2, the oxygen content of the titanium alloy powder is 0.03%~0.09%.

4. The method for low-cost preparation of titanium alloy pipe fittings using recycled coarse powder according to claim 1, characterized in that, In step 4, the set density is 50%~70%.

5. The method for low-cost preparation of titanium alloy pipe fittings using recycled coarse powder according to claim 1, characterized in that, In step 4, the pressure is set to 150MPa~300MPa and the time is 1min~20min during the cold isostatic pressing process.

6. The method for low-cost preparation of titanium alloy pipe fittings using recycled coarse powder according to claim 1, characterized in that, In step 5, the density of the cold isostatic pressed billet is 60%~80%.

7. The method for low-cost preparation of titanium alloy pipe fittings using recycled coarse powder according to claim 1, characterized in that, In step 6, the density of the hot isostatic pressed part is 99%~100%.

8. The method for low-cost preparation of titanium alloy pipe fittings using recycled coarse powder according to claim 1, characterized in that, In step 6, during the hot isostatic pressing process, the hot isostatic press is first evacuated to 10... -3 Below Pa, the temperature is increased to 800℃~1000℃ at a heating rate of 5℃ / min~15℃ / min, and held for 2h~4h. Then, argon gas is introduced to increase the pressure to 100MPa~150MPa, and the temperature and pressure are maintained for 1h~3h. Finally, the furnace is cooled and removed from the furnace at the set cooling rate.

9. The method for low-cost preparation of titanium alloy tubes using recycled coarse powder according to claim 8, characterized in that, After cooling to 50℃~200℃ at a cooling rate of 3℃ / min~15℃ / min, the product is removed from the furnace.

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