A method for precise control of high temperature and high pressure in powder hot isostatic pressing of titanium alloys
The preparation of titanium alloys by hot isostatic pressing of powder using a specific mass ratio of powder mixing and a multi-stage heating, pressurizing and cooling process has solved the problem of insufficient comprehensive performance of titanium alloys in the existing technology, and achieved high density and excellent mechanical properties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CISRI HIPEX TECHNOLOGY CO LTD
- Filing Date
- 2025-09-29
- Publication Date
- 2026-05-26
Smart Images
Figure CN121339441B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of materials, and in particular to a method for precise control of high temperature and high pressure in powder hot isostatic pressing of titanium alloys. Background Technology
[0002] Powder hot isostatic pressing technology is widely used in powder metallurgy for preparing alloy products (such as titanium alloy components), densification of castings, and diffusion bonding of various alloys due to its advantages such as high material utilization, comprehensive mechanical properties close to forging products, high near-net-shape formability of complex components, and short product production cycle.
[0003] The forming process and parameters of titanium alloys prepared by hot isostatic pressing (HIP) have a significant impact on the overall properties of titanium alloys. Therefore, optimizing the forming process and parameters of titanium alloys prepared by HIP is of great importance for improving the overall properties of titanium alloys. Summary of the Invention
[0004] In view of the above-mentioned shortcomings in the existing technology, the purpose of this application is to provide a high-temperature and high-pressure precision control method for powder hot isostatic pressing of titanium alloys, aiming to further optimize the forming process and process parameters of powder hot isostatic pressing to prepare titanium alloys, thereby improving the comprehensive performance of titanium alloys.
[0005] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:
[0006] In a first aspect, embodiments of this application provide a method for precise control of high temperature and high pressure in powder hot isostatic pressing of titanium alloys, including:
[0007] Fine-grained near-spherical titanium alloy powder and coarse-grained near-spherical titanium alloy powder are mixed at a preset mass ratio to obtain a mixed powder. The mixed powder is then loaded into a sleeve, and after being compacted, degassed, and sealed, a sealed sleeve is obtained.
[0008] The sealing sleeve is placed in a hot isostatic pressing apparatus. When the temperature is increased to 80%~90% of the first target temperature using the first heating gradient, the pressure is increased to the first target pressure using the first pressure gradient and held for 0.5~3 hours. Then, the temperature is increased to the second target temperature using the second heating gradient, and the pressure is increased to the second target pressure using the second pressure gradient and held for 1~2 hours. While maintaining the second target pressure, the temperature is increased to the third target temperature using the third heating gradient and held for 0.5~1 hour to obtain a titanium alloy ingot. The first target temperature is 400 ℃~550 ℃, the second target temperature is 600 ℃~750 ℃, and the third target temperature is 850 ℃~950 ℃.
[0009] The titanium alloy ingot is cooled to the fourth target temperature and held for 0.5 to 1 hour, then heated to the fifth target temperature and held for 0.5 to 1 hour. After that, it is water quenched to room temperature, the cladding is removed, and the titanium alloy component is obtained. The fourth target temperature is 700 to 750 ℃, and the fifth target temperature is 950 to 1050 ℃.
[0010] The beneficial effects of this application include at least the following: The technical solution provided in the embodiments of this application, by using fine-particle-size near-spherical titanium alloy powder and coarse-particle-size near-spherical titanium alloy powder in a specific mass ratio as raw materials to prepare titanium alloys, can not only reduce the raw material cost of preparing titanium alloys, but also help improve the density of titanium alloys; secondly, by optimizing the heating and pressing process and temperature, pressure and time parameters of hot isostatic pressing for preparing titanium alloys, the microstructure inheritance of titanium alloys can be effectively improved, thereby improving the density and microstructure uniformity of titanium alloys; finally, by optimizing the cooling process and temperature and time parameters of hot isostatic pressing for preparing titanium alloys, the tensile strength, yield strength and fracture toughness of titanium alloys can be improved. Attached Figure Description
[0011] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0012] Figure 1 The embodiment of this application provides a three-layer encapsulation structure consisting of a hot isostatic pressing furnace, an inert gas inside the furnace, and a sealing sleeve. Detailed Implementation
[0013] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are only for explaining this application, but the implementation of this application is not limited thereto.
[0014] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this application pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; the amounts of experimental reagents used are, unless otherwise specified, the amounts used in conventional experimental operations; and the experimental methods used are, unless otherwise specified, conventional methods.
[0015] In a first aspect, embodiments of this application provide a method for precise control of high temperature and high pressure in powder hot isostatic pressing of titanium alloys, including:
[0016] S1. Fine-grained near-spherical titanium alloy powder and coarse-grained near-spherical titanium alloy powder are mixed at a preset mass ratio to obtain a mixed powder. The mixed powder is then loaded into a sleeve, and after being compacted, degassed, and sealed, a sealed sleeve is obtained.
[0017] Near-spherical titanium alloy powder usually refers to titanium alloy powder or particles with a near-spherical morphology.
[0018] Near-spherical titanium alloy powder has high sphericity (sphericity parameters, such as aspect ratio of about 1), good flowability, high packing density, and uniform particle size and shape distribution, which is beneficial to improving the density and stability of titanium alloy materials and reducing batch-to-batch variability.
[0019] In some embodiments, fine-particle-size near-spherical titanium alloy powder and coarse-particle-size near-spherical titanium alloy powder can be prepared using existing plasma physicochemical methods, gas atomization methods, or centrifugal physicochemical methods.
[0020] By using a mixture of fine-grained near-spherical titanium alloy powder and coarse-grained near-spherical titanium alloy powder in a specific mass ratio as raw materials to prepare titanium alloys, not only can the raw material cost of preparing titanium alloys be reduced, but it is also beneficial to improve the density of titanium alloys.
[0021] S2. Place the sealing sleeve in a hot isostatic pressing (HIP) apparatus. When the temperature is increased to 80%~90% of the first target temperature using the first heating gradient, the pressure is increased to the first target pressure using the first pressure gradient. Hold the temperature and pressure for 0.5~3 hours. Then, the temperature is increased to the second target temperature using the second heating gradient, and the pressure is increased to the second target pressure using the second pressure gradient. Hold the temperature and pressure for 1~2 hours. Under the second target pressure, the temperature is increased to the third target temperature using the third heating gradient. Hold the temperature and pressure for 0.5~1 hour to obtain a titanium alloy ingot. The first target temperature is 400 ℃~550 ℃, the second target temperature is 600 ℃~750 ℃, and the third target temperature is 850 ℃~950 ℃.
[0022] When the temperature is increased to 80%~90% of the first target temperature using the first heating gradient, the pressure is increased to the first target pressure using the first pressurization gradient. This can minimize the risk of the casing cracking due to insufficient plasticity caused by low temperature and high pressure.
[0023] By adopting a stepped heating and pressurization process and optimizing the temperature, pressure, and time parameters during the heating and pressurization process, on the one hand, it can avoid severe deformation of the cladding due to a sudden temperature rise, which would affect the forming shape of the titanium alloy components and thus reduce the defect rate; on the other hand, it can effectively improve the microstructure inheritance of the titanium alloy, thereby improving the density and microstructure uniformity of the titanium alloy.
[0024] S3. Cool the titanium alloy ingot to the fourth target temperature and hold it for 0.5 to 1 hour, then heat it to the fifth target temperature and hold it for 0.5 to 1 hour. After that, quench it in water to room temperature, remove the cladding, and obtain the titanium alloy component. The fourth target temperature is 700 to 750 ℃, and the fifth target temperature is 950 to 1050 ℃.
[0025] By first cooling the titanium alloy ingot to the fourth target temperature and holding it at that temperature for 0.5 to 1 hour, then heating it to the fifth target temperature and holding it at that temperature for 0.5 to 1 hour, and finally water quenching it to room temperature, a more uniform and finer microstructure can be obtained. Phase significantly increased (isoaxial) The proportion of the phase can reach 20%~30%, which can improve the tensile strength and yield strength of titanium alloys.
[0026] The powder hot isostatic pressing process described in this application is suitable for preparing α+β type titanium alloys and near-α type titanium alloys.
[0027] Most titanium alloys are based on the β stability coefficient ( Classified by type, the β-stability coefficient refers to the sum of the ratios of the concentrations of each β-stable element (such as molybdenum, vanadium, niobium, iron, etc.) in an alloy to its respective critical concentration. When When the value is 0~0.07, it is an α-type titanium alloy; when... When the value is 0.07~0.25, it is a near-α type titanium alloy; when When the value is 0.25~1.0, it is generally called an α+β type titanium alloy; when... When the value is 1.0~2.8, it is called a near-β type titanium alloy; when... When the value is greater than 2.8, it is called a β-type titanium alloy.
[0028] In some embodiments, in step S2 above, the first temperature gradient is 5~10 ℃ / min (e.g., it can be 5 ℃ / min, 6 ℃ / min, 7 ℃ / min, 8 ℃ / min, 9 ℃ / min or 10 ℃ / min, etc.), the second temperature gradient is 2~5 ℃ / min (e.g., it can be 2 ℃ / min, 3 ℃ / min, 4 ℃ / min or 5 ℃ / min, etc.), and the third temperature gradient is 1~2 ℃ / min (e.g., it can be 1 ℃ / min or 2 ℃ / min, etc.).
[0029] In some implementations, in step S2 described above, the ratio of the first target pressure to the second target pressure is 1:1 to 3.
[0030] By controlling the ratio of the first target pressure to the second target pressure to be 1:1 to 3, the grain size and microstructure uniformity of titanium alloy can be controlled while achieving complete powder densification, reducing component segregation, ensuring component uniformity, and taking into account both process stability and economy.
[0031] In some embodiments, in step S2 above, the first boost gradient is 0.5~2 MPa / min, and the second boost gradient is 0.5~1 MPa / min.
[0032] In some embodiments, in step S3 above, cooling the titanium alloy ingot to a fourth target temperature includes: cooling the titanium alloy ingot from a third target temperature to 800°C at a cooling rate of 8~10°C / min, and then cooling the titanium alloy ingot from 800°C to the fourth target temperature at a cooling rate of 3~5°C / min.
[0033] In some embodiments, during the heat preservation and pressure holding period, the temperature fluctuation range inside the furnace of the hot isostatic pressing equipment is maintained within a preset temperature threshold range, and the pressure fluctuation range inside the furnace is maintained within a preset pressure threshold range. The preset temperature range is typically -5℃ to 5℃, and the preset pressure range is typically -1 MPa to 1 MPa.
[0034] In the process of preparing titanium alloys by hot isostatic pressing (HIP), scientifically sound high-temperature and high-pressure conditions are one of the key technical points to ensure the comprehensive performance of the formed titanium alloy. Considering that the densification and deformation process of titanium alloy powder under high-temperature and high-pressure conditions is complex and dynamically changing, this application uses multiple sets of sensors for zoned and stepped temperature and pressure control to ensure the stability, uniformity, and synchronicity of the temperature and pressure field distribution inside the hot isostatic pressing furnace.
[0035] During hot isostatic pressing (HIP), the hot isostatic pressing furnace, the inert gas inside the furnace (usually argon), and the sealing casing form a three-layer encapsulation structure from the outside in (e.g., Figure 1 (As shown). During the heating-holding stage, it is an unstable heat exchange process between the hot isostatic pressing furnace, the inert gas inside the furnace, and the sealing sleeve. As the temperature of the hot isostatic pressing furnace rises, the sealing sleeve is continuously heated.
[0036] As an example, please refer to Figure 1 First temperature sensors A, B, C, and D (first sensor group) can be installed at the four apex corners of the inner wall of the hot isostatic pressing furnace to monitor the temperature change of the inner wall of the furnace; second temperature sensors E and F (second sensor group) can be installed inside the hot isostatic pressing furnace to monitor the temperature change of the inert gas inside the furnace; and third temperature sensors G and H (third sensor group) can be installed on the outer surface of the sealing sleeve to monitor the temperature change of the outer surface of the sealing sleeve.
[0037] The location and number of the first, second, and third temperature sensors can be flexibly adjusted according to actual conditions, and this application embodiment does not impose any restrictions on this.
[0038] During the first heating-holding stage (the stage of heating to the first target temperature), the controller (which can be an electronic device such as a computer or laptop) can collect the inner wall temperature of the hot isostatic pressing furnace in real time through the first temperature sensors A, B, C, and D. , , and The temperature of the inert gas inside the furnace is collected in real time by the second temperature sensors E and F. , The outer surface temperature of the sealing sleeve is collected in real time by the third temperature sensors G and H. , Next, based on the collected inner wall temperature of the hot isostatic pressing furnace... , , and Data fitting was performed to obtain the first real-time temperature curve; based on the collected inert gas temperature inside the furnace... , Data fitting was performed to obtain a second real-time temperature curve; based on the collected outer surface temperature of the sealing sleeve... , Data fitting is performed to obtain a third real-time temperature curve. The first real-time temperature curve is compared with a first historical temperature curve (a temperature curve fitted based on historical hot isostatic pressing furnace inner wall temperatures) to determine if the current hot isostatic pressing furnace inner wall temperature is abnormal (e.g., if the current hot isostatic pressing furnace inner wall temperature fluctuation exceeds a preset temperature threshold range or there is a step change, then the current hot isostatic pressing furnace inner wall temperature is determined to be abnormal). The second real-time temperature curve is compared with a second historical temperature curve (a temperature curve fitted based on historical furnace inert gas temperatures) to determine if the current furnace inert gas temperature is abnormal (e.g., if the current furnace inert gas temperature fluctuation exceeds a preset temperature threshold range or there is a step change, then the current furnace inert gas temperature is determined to be abnormal). The third real-time temperature curve is compared with a third historical temperature curve (a temperature curve fitted based on historical sealing sleeve outer surface temperatures) to determine if the current sealing sleeve outer surface temperature is abnormal (e.g., if the current sealing sleeve outer surface temperature fluctuation exceeds a preset temperature threshold range or there is a step change, then the current sealing sleeve outer surface temperature is determined to be abnormal). If the inner wall temperature of the hot isostatic pressing furnace, the inert gas temperature inside the furnace, and the outer surface temperature of the sealing sleeve are all normal, then the temperature control of the first heating-holding stage is considered normal, and no further action is required. If at least one of the following is abnormal, then the temperature control of the first heating-holding stage is considered abnormal, and the heating power and heating area of the hot isostatic pressing furnace are adjusted until the temperature control of the first heating-holding stage is normal.
[0039] Similarly, the temperature control process for the second heating-holding stage (the stage of heating to the second target temperature) and the third heating-holding stage (the stage of heating to the third target temperature) can be controlled by referring to the temperature control process of the first heating-holding stage, and will not be repeated here.
[0040] Similarly, the pressure control process in the first pressurization-holding stage (pressurization to the first target pressure) and the second pressurization-holding stage (pressurization to the second target pressure) can be controlled by referring to the temperature control process in the first heating-holding stage, and will not be repeated here.
[0041] As another example, please refer to Figure 1 The controller (which can be an electronic device such as a computer or laptop) can collect the inner wall temperature of the hot isostatic pressing furnace in real time through the first temperature sensors A, B, C, and D. , , and The temperature of the inert gas inside the furnace is collected in real time by the second temperature sensors E and F. , The outer surface temperature of the sealing sleeve is collected in real time by the third temperature sensors G and H. , The thermophysical parameters of the sealing casing (including thermal conductivity, specific heat capacity, thermal diffusivity, coefficient of thermal expansion, phase transformation related parameters, thermal shock toughness, high-temperature strength, density, etc.), the thermophysical parameters of titanium alloy powder (including thermal conductivity, specific heat capacity, thermal diffusivity, bulk density and true density, coefficient of thermal expansion, phase transformation temperature, melting point, latent heat of fusion, etc.), and the thermophysical parameters of the inert gas in the furnace (including density, specific heat capacity, thermal conductivity, compressibility factor, diffusivity, coefficient of thermal expansion, etc.) are obtained. The obtained parameters are input into the densification model, and the predicted result of the relative density of the titanium alloy is output. The predicted result is compared with the target result. If the absolute value of the difference between the predicted result and the target result is greater than the preset threshold, the temperature and pressure of the hot isostatic pressing equipment are adjusted according to the temperature control process / pressure control process in the example above.
[0042] As an example, the main influencing factors of densification of titanium alloy powder during hot isostatic pressing include the change mechanisms of elasticity, viscoplasticity, creep, and thermal strain. Therefore, a densification model can be constructed based on the influence of the change mechanisms of elasticity, viscoplasticity, creep, and thermal strain on the densification of titanium alloy powder during hot isostatic pressing.
[0043] In some embodiments, in step S1 above, the average particle size of the fine-particle-size near-spherical titanium alloy powder is 5~50 µm, and the average particle size of the coarse-particle-size near-spherical titanium alloy powder is 100~200 µm.
[0044] In some embodiments, in step S1 above, the mass ratio of fine-particle-size near-spherical titanium alloy powder to coarse-particle-size near-spherical titanium alloy powder is 5~10:2~3.
[0045] Using a mixture of fine-grained near-spherical titanium alloy powder and coarse-grained near-spherical titanium alloy powder in a specific mass ratio as raw material to prepare titanium alloy components is beneficial to improving the tap density of the powder, increasing the compactness of the titanium alloy components, expanding the range of usable particle sizes of titanium alloy powder raw materials, improving raw material utilization, and reducing raw material costs.
[0046] In some embodiments, in step S1 above, the tap density of the mixed powder in the sealing sleeve is greater than or equal to 65%.
[0047] Controlling the tap density of the mixed powder in the sealed envelope to be greater than or equal to 65% is beneficial to improving the density of titanium alloys.
[0048] In some embodiments, in step S1 above, the sheath is a low-carbon steel sheath.
[0049] This application has undergone multiple experiments, and some of the test results are presented here for reference to further describe the invention in detail. The following is a detailed description in conjunction with specific embodiments.
[0050] Example 1
[0051] This embodiment provides a method for preparing titanium alloys by hot isostatic pressing of powder, including the following steps:
[0052] S1. Fine-grained near-spherical Ti-6Al-4V powder (average particle size 12 µm, sphericity greater than 98%, purity greater than 99%) and coarse-grained near-spherical Ti-6Al-4V powder (average particle size 110 µm, sphericity greater than 98%, purity greater than 99%) are mixed at a mass ratio of 5:2 to obtain a mixed powder. Then, the mixed powder is packed into a low-carbon steel sleeve for compaction (compacted density 68%), degassing, and sealing welding to obtain a sealed sleeve.
[0053] S2. Place the sealing sleeve from step S1 into a hot isostatic pressing (HIP) apparatus. When the temperature is increased to 320°C (80% of the first target temperature of 400°C) at a first heating gradient of 7°C / min, the pressure is increased to the first target pressure of 100 MPa at a first pressure gradient of 1 MPa / min, while simultaneously continuing to heat to the first target temperature of 400°C, and held at the temperature and pressure for 1 hour. Next, the temperature is increased to the second target temperature of 750°C at a second heating gradient of 5°C / min, while simultaneously increasing the pressure to the second target pressure of 120 MPa at a second pressure gradient of 0.5 MPa / min, and held at the temperature and pressure for 2 hours. Afterward, while maintaining the second target pressure of 120 MPa, the temperature is increased to the third target temperature of 950°C at a third heating gradient of 1.5°C, and held at the temperature and pressure for 1 hour to obtain a titanium alloy ingot.
[0054] S3. The titanium alloy ingot obtained in step S2 is cooled from the third target temperature of 950 ℃ to 800 ℃ at a cooling rate of 10 ℃ / min, and then cooled from 800 ℃ to the fourth target temperature of 700 ℃ at a cooling rate of 3 ℃ / min. The temperature is held for 0.5 hours, then heated to 1050 ℃ and held for 0.5 hours. After that, it is water quenched to room temperature, and the low carbon steel cladding is removed by machining to obtain the titanium alloy component.
[0055] Example 2
[0056] This embodiment provides a method for preparing titanium alloy components by hot isostatic pressing of powder, including the following steps:
[0057] S1. Fine-grained near-spherical Ti-6Al-4V powder (average particle size 5 µm, sphericity greater than 98%, purity greater than 99%) and coarse-grained near-spherical Ti-6Al-4V powder (average particle size 200 µm, sphericity greater than 98%, purity greater than 99%) are mixed at a mass ratio of 5:3 to obtain a mixed powder. Then, the mixed powder is packed into a low-carbon steel sleeve for compaction (compacted density of 66%), degassing, and sealing welding to obtain a sealed sleeve.
[0058] S2. Place the sealing sleeve from step S1 into a hot isostatic pressing (HIP) apparatus. When the temperature is increased to 440°C (80% of the first target temperature of 550°C) at a first heating gradient of 5°C / min, the pressure is increased to the first target pressure of 100 MPa at a first pressure gradient of 2 MPa / min, while simultaneously continuing to heat to the first target temperature of 550°C, and held at the temperature and pressure for 1 hour. Next, the temperature is increased to the second target temperature of 750°C at a second heating gradient of 3°C / min, while simultaneously increasing the pressure to the second target pressure of 130 MPa at a second pressure gradient of 1 MPa / min, and held at the temperature and pressure for 1.5 hours. Afterward, while maintaining the second target pressure of 130 MPa, the temperature is increased to the third target temperature of 950°C at a third heating gradient of 2°C, and held at the temperature and pressure for 1 hour to obtain a titanium alloy ingot.
[0059] S3. The titanium alloy ingot obtained in step S2 is cooled from the third target temperature of 950 ℃ to 800 ℃ at a cooling rate of 8 ℃ / min, and then cooled from 800 ℃ to the fourth target temperature of 750 ℃ at a cooling rate of 4 ℃ / min. The temperature is held for 0.5 hours, then heated to 1050 ℃ and held for 0.5 hours. After that, it is water quenched to room temperature, and the low carbon steel cladding is removed by machining to obtain the titanium alloy component.
[0060] Example 3
[0061] This embodiment provides a method for preparing titanium alloy components by hot isostatic pressing of powder, including the following steps:
[0062] S1. Fine-grained near-spherical Ti-6Al-4V powder (average particle size 20 µm, sphericity greater than 98%, purity greater than 99%) and coarse-grained near-spherical Ti-6Al-4V powder (average particle size 150 µm, sphericity greater than 98%, purity greater than 99%) are mixed at a mass ratio of 10:3 to obtain a mixed powder. Then, the mixed powder is packed into a low-carbon steel sleeve for compaction (compacted density 67%), degassing, and sealing welding to obtain a sealed sleeve.
[0063] S2. Place the sealing sleeve from step S1 into a hot isostatic pressing (HIP) apparatus. When the temperature is increased to 440°C (80% of the first target temperature of 550°C) at a first heating gradient of 10°C / min, the pressure is increased to the first target pressure of 110 MPa at a first pressure gradient of 0.5 MPa / min, while simultaneously continuing to heat to the first target temperature of 550°C and holding the temperature and pressure for 1 hour. Next, the temperature is increased to the second target temperature of 600°C at a second heating gradient of 2°C / min, while simultaneously increasing the pressure to the second target pressure of 140 MPa at a second pressure gradient of 1 MPa / min and holding the temperature and pressure for 1 hour. Afterward, while maintaining the second target pressure of 140 MPa, the temperature is increased to the third target temperature of 950°C at a third heating gradient of 1°C and held for 1 hour to obtain a titanium alloy ingot.
[0064] S3. The titanium alloy ingot obtained in step S2 is cooled from the third target temperature of 950 ℃ to 800 ℃ at a cooling rate of 9 ℃ / min, and then cooled from 800 ℃ to the fourth target temperature of 750 ℃ at a cooling rate of 3 ℃ / min. The temperature is held for 0.5 hours, then heated to 1050 ℃ and held for 0.5 hours. After that, it is water quenched to room temperature, and the low carbon steel cladding is removed by machining to obtain the titanium alloy component.
[0065] Comparative Example 1
[0066] This comparative example provides a method for preparing titanium alloy components by hot isostatic pressing of powder. The preparation steps are basically the same as those of the titanium alloy component preparation method in Example 2. The only difference is that the mixed powder in step S1 is replaced in equal amounts with fine-particle-size near-spherical Ti-6Al-4V powder (average particle size of 5 µm, sphericity greater than 98%, purity greater than 99%).
[0067] Comparative Example 2
[0068] This comparative example provides a method for preparing titanium alloy components by hot isostatic pressing of powder. The preparation steps are basically the same as those of the titanium alloy component preparation method in Example 2. The only difference is that the mixed powder in step S1 is replaced by an equal amount of coarse-grained near-spherical Ti-6Al-4V powder (average particle size of 200 µm, sphericity greater than 98%, purity greater than 99%).
[0069] Comparative Example 3
[0070] This comparative example provides a method for preparing titanium alloy components by hot isostatic pressing of powder. The preparation steps are basically the same as those of the titanium alloy component preparation method in Example 2, with the only difference being:
[0071] S1. Fine-grained near-spherical Ti-6Al-4V powder (average particle size 5 µm, sphericity greater than 98%, purity greater than 99%) and coarse-grained near-spherical Ti-6Al-4V powder (average particle size 200 µm, sphericity greater than 98%, purity greater than 99%) are mixed at a mass ratio of 3:5 to obtain a mixed powder. Then, the mixed powder is packed into a low-carbon steel sleeve for compaction (compacted density 66%), degassing, and sealing welding to obtain a sealed sleeve.
[0072] Comparative Example 4
[0073] This comparative example provides a method for preparing titanium alloy components by hot isostatic pressing of powder. The preparation steps are basically the same as those of the titanium alloy component preparation method in Example 2, with the only difference being:
[0074] S1. Fine-grained near-spherical Ti-6Al-4V powder (average particle size 5 µm, sphericity greater than 98%, purity greater than 99%) and coarse-grained near-spherical Ti-6Al-4V powder (average particle size 200 µm, sphericity greater than 98%, purity greater than 99%) are mixed at a mass ratio of 1:1 to obtain a mixed powder. Then, the mixed powder is packed into a low-carbon steel sleeve for compaction (compacted density 66%), degassing, and sealing welding to obtain a sealed sleeve.
[0075] Comparative Example 5
[0076] This comparative example provides a method for preparing titanium alloy components by hot isostatic pressing of powder, comprising the following steps:
[0077] S1. Fine-grained near-spherical Ti-6Al-4V powder (average particle size 5 µm, sphericity greater than 98%, purity greater than 99%) and coarse-grained near-spherical Ti-6Al-4V powder (average particle size 200 µm, sphericity greater than 98%, purity greater than 99%) are mixed at a mass ratio of 5:3 to obtain a mixed powder. Then, the mixed powder is packed into a low-carbon steel sleeve for compaction (compacted density of 66%), degassing, and sealing welding to obtain a sealed sleeve.
[0078] S2. Place the sealing sleeve from step S1 into a hot isostatic pressing apparatus, heat it to 950 ℃ at a temperature gradient of 5 ℃ / min, and simultaneously pressurize it to 130 MPa at a pressure gradient of 1 MPa / min. Hold the temperature and pressure for 3.5 hours to obtain a titanium alloy ingot.
[0079] S3. The titanium alloy ingot obtained in step S2 is cooled from the third target temperature of 950 ℃ to 800 ℃ at a cooling rate of 8 ℃ / min, and then cooled from 800 ℃ to the fourth target temperature of 750 ℃ at a cooling rate of 4 ℃ / min. The temperature is held for 0.5 hours, then heated to 1050 ℃ and held for 0.5 hours. After that, it is water quenched to room temperature, and the low carbon steel cladding is removed by machining to obtain the titanium alloy component.
[0080] Comparative Example 6
[0081] This comparative example provides a method for preparing titanium alloy components by hot isostatic pressing of powder, comprising the following steps:
[0082] S1. Fine-grained near-spherical Ti-6Al-4V powder (average particle size 5 µm, sphericity greater than 98%, purity greater than 99%) and coarse-grained near-spherical Ti-6Al-4V powder (average particle size 200 µm, sphericity greater than 98%, purity greater than 99%) are mixed at a mass ratio of 5:3 to obtain a mixed powder. Then, the mixed powder is packed into a low-carbon steel sleeve for compaction (compacted density of 66%), degassing, and sealing welding to obtain a sealed sleeve.
[0083] S2. Place the sealing sleeve from step S1 into a hot isostatic pressing (HIP) apparatus. When the temperature is increased to 440°C (80% of the first target temperature of 550°C) at a first heating gradient of 5°C / min, start increasing the pressure to the first target pressure of 100 MPa at a first pressure gradient of 2 MPa / min, and simultaneously continue to increase the temperature to the first target temperature of 550°C, and hold the temperature and pressure for 1 hour. Then, increase the temperature to the second target temperature of 950°C at a second heating gradient of 3°C / min, and simultaneously increase the pressure to the second target pressure of 130 MPa at a second pressure gradient of 1 MPa / min, and hold the temperature and pressure for 2.5 hours to obtain a titanium alloy ingot.
[0084] S3. The titanium alloy ingot obtained in step S2 is cooled from the third target temperature of 950 ℃ to 800 ℃ at a cooling rate of 8 ℃ / min, and then cooled from 800 ℃ to the fourth target temperature of 750 ℃ at a cooling rate of 4 ℃ / min. The temperature is held for 0.5 hours, then heated to 1050 ℃ and held for 0.5 hours. After that, it is water quenched to room temperature, and the low carbon steel cladding is removed by machining to obtain the titanium alloy component.
[0085] Comparative Example 7
[0086] This comparative example provides a method for preparing titanium alloy components by hot isostatic pressing of powder. The preparation steps are basically the same as those of the titanium alloy component preparation method in Example 2. The only difference is that in step S3, the titanium alloy ingot obtained in step S2 is cooled to room temperature in the furnace and the low carbon steel cladding is removed by machining to obtain the titanium alloy component.
[0087] Comparative Example 8
[0088] This comparative example provides a method for preparing titanium alloy components by hot isostatic pressing of powder. The preparation steps are basically the same as those of the titanium alloy component preparation method in Example 2. The only difference is that in step S3, the titanium alloy ingot obtained in step S2 is cooled from the third target temperature of 950°C to 800°C at a cooling rate of 8°C / min, and then cooled from 800°C to room temperature at a cooling rate of 4°C / min.
[0089] The titanium alloy components prepared in Examples 1-3 and Comparative Examples 1-8 of this application were subjected to the following performance tests, and the test results are shown in Table 1.
[0090] The test items are as follows:
[0091] (1) Density: The density of the titanium alloy components prepared in Examples 1-3 and Comparative Examples 1-8 of this application was tested according to the standard ASTM E2109-23 Metallography: Quantitative analysis of porosity. The test results are shown in Table 1.
[0092] (2) Tensile strength and yield strength: The tensile strength and yield strength of the titanium alloy components prepared in Examples 1 to 3 and Comparative Examples 1 to 8 of this application were tested according to the standard GB / T 228.1-2021 "Metallic Materials - Tensile Testing at Room Temperature".
[0093] (3) Fracture toughness:
[0094] The fracture toughness of the samples was tested using the Vickers indentation microfracture (IM) method. The IM method involves applying a Vickers hardness tester to the polished surface of the sample. Due to the significant stress concentration at the four vertices of the quadrilateral indenter, initial cracks are induced first in the plastic zone below the indenter. When the pressure exceeds the critical load, the cracks fully develop, penetrating the surface to form visible cracks. The fracture toughness value is calculated according to the following formula (1):
[0095] (1)
[0096] In the formula, H V This is Vickers hardness, where 'a' is the half-length of the indentation diagonal, 'c' is the half-length of the crack, and 'K' is the hardness. IC This represents the fracture toughness value.
[0097] Table 1
[0098]
[0099] As shown in Table 1, the titanium alloy components prepared by the method of this application can achieve a density of over 99%, a tensile strength of over 968 MPa, a yield strength of over 903 MPa, and a fracture toughness of over 126 MPa·m. 1 / 2 In summary, its overall performance is excellent.
[0100] The comparison results between Example 2 and Comparative Examples 1-4 show that the titanium alloy component prepared by Example 2 using a mixture of fine-grained near-spherical titanium alloy powder and coarse-grained near-spherical titanium alloy powder in a mass ratio of 5:3 as raw material can achieve a density of over 99%, a tensile strength of over 980 MPa, a yield strength of over 923 MPa, and a fracture toughness of over 150 MPa·m. 1 / 2 The above demonstrates excellent overall performance. However, the titanium alloy components prepared using comparative examples 1-4, which employed either a single fine-particle-size near-spherical titanium alloy powder, a single coarse-particle-size near-spherical titanium alloy powder, a mixture of fine-particle-size and coarse-particle-size near-spherical titanium alloy powders at a mass ratio of 3:5, or a mixture of fine-particle-size and coarse-particle-size near-spherical titanium alloy powders at a mass ratio of 1:1, exhibit significantly lower density, tensile strength, yield strength, and fracture toughness than the titanium alloy component prepared in Example 2. Therefore, using a mixture of fine-particle-size and coarse-particle-size near-spherical titanium alloy powders at a mass ratio of 5:3 as raw material can improve the density, tensile strength, yield strength, and fracture toughness of the titanium alloy component, thereby enhancing its overall performance.
[0101] The comparison results between Example 2 and Comparative Examples 5-6 show that, through a three-stage heating and pressurizing-heat holding and pressurizing treatment, the titanium alloy component prepared in Example 2 can achieve a density of over 99%, a tensile strength of 980 MPa, a yield strength of 923 MPa, and a fracture toughness of 150 MPa·m. 1 / 2 Comparative Example 5, which uses a one-step hot isostatic pressing process to prepare titanium alloy components, yielded titanium alloy components with a density of 97.88%, a tensile strength of 865 MPa, a yield strength of 872 MPa, and a fracture toughness of 98 MPa·m. 1 / 2 The results were all significantly lower than those of the titanium alloy component obtained in Example 2. Comparative Example 6 used a two-step hot isostatic pressing method to prepare titanium alloy components, resulting in a titanium alloy component with a density of 98.96%, a tensile strength of 847 MPa, a yield strength of 869 MPa, and a fracture toughness of 102 MPa·m. 1 / 2The density, tensile strength, yield strength, and fracture toughness of the titanium alloy components are significantly lower than those obtained in Example 2. It is evident that this application, through a three-stage heating and pressurizing-heating and pressurizing process, can significantly improve the density, tensile strength, yield strength, and fracture toughness of the titanium alloy components, thereby enhancing their overall performance.
[0102] The comparison results between Example 2 and Comparative Examples 7-8 show that, through a two-step stepped cooling and one-step solution treatment, Example 2 achieves a titanium alloy component with a density of over 99%, a tensile strength of 980 MPa, a yield strength of 923 MPa, and a fracture toughness of 150 MPa·m. 1 / 2 The titanium alloy component prepared by furnace cooling in Comparative Example 7 had a density of 98.23%, a tensile strength of 855 MPa, a yield strength of 883 MPa, and a fracture toughness of 95 MPa·m. 1 / 2 The density of the titanium alloy component prepared in Comparative Example 8 using a two-step stepped cooling process was 99.01%, the tensile strength was 905 MPa, the yield strength was 894 MPa, and the fracture toughness was 107 MPa·m. 1 / 2 The results were all significantly lower than those of the titanium alloy components obtained in Example 2. It is evident that the two-step stepped cooling + one-step solution treatment method employed in this application can significantly improve the density, tensile strength, yield strength, and fracture toughness of titanium alloy components, thereby enhancing the overall performance of the titanium alloy components.
[0103] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.
Claims
1. A method for precise control of high temperature and high pressure in powder hot isostatic pressing of titanium alloys, characterized in that, include: Fine-grained near-spherical titanium alloy powder and coarse-grained near-spherical titanium alloy powder are mixed at a preset mass ratio to obtain a mixed powder. The mixed powder is then placed in a sleeve, which is compacted, degassed, and sealed to obtain a sealed sleeve. The mass ratio of the fine-grained near-spherical titanium alloy powder to the coarse-grained near-spherical titanium alloy powder is 5~10:2~3. The sealing sleeve is placed in a hot isostatic pressing (HIP) apparatus. While heating to 80%–90% of the first target temperature using a first heating gradient, the pressure is increased to the first target pressure using a first pressure gradient and held for 0.5–3 hours. Then, the temperature is increased to the second target temperature using a second heating gradient, and the pressure is increased to the second target pressure using a second pressure gradient and held for 1–2 hours. While maintaining the second target pressure, the temperature is increased to the third target temperature using a third heating gradient and held for 0.5–1 hour to obtain a titanium alloy ingot. The first target temperature is 400 °C–550 °C, the second target temperature is 600 °C–750 °C, and the third target temperature is 850 °C–950 °C. The ratio of the first target pressure to the second target pressure is 1:1–3. The titanium alloy ingot is cooled to a fourth target temperature and held for 0.5 to 1 hour, then heated to a fifth target temperature and held for 0.5 to 1 hour, and then water-quenched to room temperature. The cladding is removed to obtain a titanium alloy component. The fourth target temperature is 700 to 750 °C, and the fifth target temperature is 950 to 1050 °C.
2. The method for precise control of high temperature and high pressure of powder hot isostatic pressing titanium alloy according to claim 1, characterized in that, The first heating gradient is 5~10 ℃ / min, the second heating gradient is 2~5 ℃ / min, and the third heating gradient is 1~2 ℃ / min.
3. The high-temperature and high-pressure precision control method for powder hot isostatic pressing titanium alloy according to claim 1, wherein the first pressure gradient is 0.5~2 MPa / min and the second pressure gradient is 0.5~1 MPa / min.
4. The method for precise control of high temperature and high pressure of powder hot isostatic pressing titanium alloy according to claim 1, characterized in that, Cooling the titanium alloy ingot to a fourth target temperature includes: The titanium alloy ingot is cooled from the third target temperature to 800 ℃ at a cooling rate of 8~10 ℃ / min, and then cooled from 800 ℃ to the fourth target temperature at a cooling rate of 3~5 ℃ / min.
5. The method for precise control of high temperature and high pressure of powder hot isostatic pressing titanium alloy according to claim 1, characterized in that, During the heat preservation and pressure holding period, the temperature fluctuation range inside the furnace of the hot isostatic pressing equipment is maintained within a preset temperature threshold range, and the pressure fluctuation range inside the furnace is maintained within a preset pressure threshold range.
6. The method for precise control of high temperature and high pressure of powder hot isostatic pressing titanium alloy according to claim 1, characterized in that, The average particle size of the fine-grained near-spherical titanium alloy powder is 5~50 µm, and the average particle size of the coarse-grained near-spherical titanium alloy powder is 100~200 µm.
7. The method for precise control of high temperature and high pressure of powder hot isostatic pressing titanium alloy according to claim 1, characterized in that, The mixed powder in the sealed envelope is compacted to a density greater than or equal to 65%.
8. The method for precise control of high temperature and high pressure of powder hot isostatic pressing titanium alloy according to claim 1, characterized in that, The sheath is made of low-carbon steel.