High-temperature and high-pressure accurate control method for powder hot isostatic pressing titanium alloy

Abstract

The invention relates to the field of materials, and provides a high-temperature and high-pressure accurate control method for powder hot isostatic pressing titanium alloy. The method comprises the following steps: placing a sealed package in hot isostatic pressing equipment, raising the temperature to 80-90% of 400-550 DEG C at a first temperature rise gradient, raising the pressure to a first target pressure at a first pressure rise gradient, keeping the temperature and the pressure, raising the temperature to 600-750 DEG C at a second temperature rise gradient, raising the pressure to a second target pressure at a second pressure rise gradient, keeping the temperature and the pressure, and cooling to the room temperature; raising the temperature to 850-950 DEG C according to a third temperature raising gradient, and keeping the temperature and the pressure to obtain a titanium alloy ingot; and the titanium alloy ingot is cooled to 700-750 DEG C and subjected to heat preservation for 0.5-1 h, then the titanium alloy ingot is heated to 950-1050 DEG C and subjected to heat preservation for 0.5-1 h, water quenching is conducted to the room temperature, and the titanium alloy component is obtained. The compactness, tensile strength, yield strength and fracture toughness of the titanium alloy component can be improved, and the comprehensive performance is more excellent.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of materials, in particular to a high-temperature and high-pressure precise control method for powder hot isostatic pressing titanium alloy. BACKGROUND

[0002] The powder hot isostatic pressing technology is widely applied to powder metallurgy preparation of alloy products (such as titanium alloy components), densification of castings, diffusion connection of various alloys and the like due to the characteristics of high material utilization, comprehensive mechanical properties close to forged products, high near-net forming degree for components with complex shapes, short product production cycle and the like.

[0003] The forming process and process parameters of the powder hot isostatic pressing titanium alloy have a great influence on the comprehensive performance of the titanium alloy. Therefore, optimizing the forming process and process parameters of the powder hot isostatic pressing titanium alloy has important significance for improving the comprehensive performance of the titanium alloy. SUMMARY

[0004] In view of the above problems in the prior art, the present application aims to provide a high-temperature and high-pressure precise control method for powder hot isostatic pressing titanium alloy, which is designed to further optimize the forming process and process parameters of the powder hot isostatic pressing titanium alloy, thereby improving the comprehensive performance of the titanium alloy.

[0005] To achieve the above-mentioned application purposes, the technical solutions adopted by the present application are as follows: In a first aspect, the present application provides a high-temperature and high-pressure precise control method for powder hot isostatic pressing titanium alloy, comprising: Mixing fine-grained near-spherical titanium alloy powder and coarse-grained near-spherical titanium alloy powder according to a preset mass ratio to obtain mixed powder, and loading the mixed powder into a capsule, and after vibration, degassing and sealing treatment, obtaining a sealed capsule; Placing the sealed capsule in a hot isostatic pressing device, starting to increase the pressure to a first target pressure at a first pressure increasing gradient when the temperature is increased to 80%~90% of a first target temperature, and keeping the temperature and pressure for 0.5~3 hours, then increasing the temperature to a second target temperature at a second temperature increasing gradient while increasing the pressure to a second target pressure at a second pressure increasing gradient, and keeping the temperature and pressure for 1~2 hours, and then increasing the temperature to a third target temperature at a third temperature increasing gradient while maintaining the second target pressure, and keeping the temperature and pressure for 0.5~1 hours, to obtain a titanium alloy ingot, wherein the first target temperature is 400 ℃~550 ℃, the second target temperature is 600 ℃~750 ℃, and the third target temperature is 850 ℃~950 ℃; Cooling the titanium alloy ingot to a fourth target temperature and holding for 0.5-1 hours, then heating to a fifth target temperature and holding for 0.5-1 hours, and then water quenching to room temperature, removing the can, to obtain the titanium alloy component, wherein the fourth target temperature is 700-750 DEG C, and the fifth target temperature is 950-1050 DEG C.

[0006] The beneficial effects of the present application at least include: the technical scheme provided by the embodiments of the present application, by using the fine particle size near-spherical titanium alloy powder and the coarse particle size near-spherical titanium alloy powder with a specific mass ratio as raw materials to prepare the titanium alloy, not only the raw material cost of preparing the titanium alloy can be reduced, but also the density of the titanium alloy can be improved; secondly, by optimizing the temperature and pressure increasing process of the hot isostatic pressing for preparing the titanium alloy and the temperature, pressure and time parameters, the microstructure heredity of the titanium alloy can be effectively improved, thereby improving the density and microstructure uniformity of the titanium alloy; finally, by optimizing the cooling process flow and the temperature and time parameters of the hot isostatic pressing for preparing the titanium alloy, the tensile strength, yield strength and fracture toughness of the titanium alloy can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0007] In order to more clearly illustrate the technical schemes in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0008] Figure 1 The three-layer wrapping structure is formed by the hot isostatic pressing furnace, the inert gas in the furnace and the sealing can. DETAILED DESCRIPTION

[0009] In order to make the technical problems, technical schemes and beneficial effects of the present application more clearly understood, the following will further describe the present application with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but the implementation of the present application is not limited thereto.

[0010] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as generally understood by those skilled in the art to which the present application belongs. The experimental reagents used in the following embodiments, unless otherwise specified, are conventional biochemical reagents; the experimental reagent amount, unless otherwise specified, is the reagent amount in conventional experimental operation; the experimental method, unless otherwise specified, is the conventional method.

[0011] In a first aspect, the embodiments of the present application provide a high-temperature and high-pressure accurate control method for powder hot isostatic pressing titanium alloy, comprising: S1, mixing the fine-grained near-spherical titanium alloy powder and the coarse-grained near-spherical titanium alloy powder according to a preset mass ratio to obtain a mixed powder, and loading the mixed powder into a can, and after vibration, degassing and sealing treatment, a sealed can is obtained.

[0012] The near-spherical titanium alloy powder generally refers to a titanium alloy powder or particle having a morphology close to a sphere.

[0013] The near-spherical titanium alloy powder has a high sphericity (sphericity parameter, such as an aspect ratio of about 1), good fluidity, high bulk density, and uniform particle size and shape distribution, which is beneficial to improve the density and stability of the titanium alloy material and reduce the batch-to-batch difference.

[0014] In some embodiments, the fine-grained near-spherical titanium alloy powder and the coarse-grained near-spherical titanium alloy powder can be prepared by using existing plasma physical and chemical methods, gas atomization methods or centrifugal physical and chemical methods.

[0015] By using the mixed powder of the fine-grained near-spherical titanium alloy powder and the coarse-grained near-spherical titanium alloy powder with a specific mass ratio as raw material to prepare the titanium alloy, not only the raw material cost of preparing the titanium alloy can be reduced, but also the density of the titanium alloy can be improved.

[0016] S2, placing the sealed can in a hot isostatic pressing device, starting to increase the pressure to the first target pressure at the first pressure increasing gradient when the temperature is increased to 80% to 90% of the first target temperature, and keeping the temperature and pressure for 0.5 to 3 hours, then increasing the temperature to the second target temperature at the second temperature increasing gradient, and increasing the pressure to the second target pressure at the second pressure increasing gradient, keeping the temperature and pressure for 1 to 2 hours, and then increasing the temperature to the third target temperature at the third temperature increasing gradient under the second target pressure, keeping the temperature and pressure for 0.5 to 1 hour, to obtain a titanium alloy ingot, wherein the first target temperature is 400 ℃ to 550 ℃, the second target temperature is 600 ℃ to 750 ℃, and the third target temperature is 850 ℃ to 950 ℃.

[0017] When the temperature is increased to 80% to 90% of the first target temperature at the first temperature increasing gradient, the pressure is started to increase to the first target pressure at the first pressure increasing gradient, which can avoid the problem of can rupture caused by low temperature and high pressure.

[0018] By using the stepwise temperature and pressure increasing process and optimizing the temperature, pressure and time parameters in the temperature and pressure increasing process, on the one hand, the serious deformation of the can caused by sudden temperature rise can be avoided, thereby affecting the forming shape of the titanium alloy component and reducing the rate of defective products; on the other hand, the microstructure heredity of the titanium alloy can be effectively improved, thereby improving the density and microstructure uniformity of the titanium alloy.

[0019] S3, cooling the titanium alloy ingot to a fourth target temperature and holding for 0.5-1 hour, then heating to a fifth target temperature and holding for 0.5-1 hour, and then water quenching to room temperature, removing the sheath, to obtain a titanium alloy component, wherein the fourth target temperature is 700-750 ℃, and the fifth target temperature is 950-1050 ℃.

[0020] By first cooling the titanium alloy ingot to a fourth target temperature and holding for 0.5-1 hour, then heating to a fifth target temperature and holding for 0.5-1 hour, and then water quenching to room temperature, a more uniform and fine microstructure can be obtained, and the proportion of equiaxed phase in the microstructure structure can reach 20%-30%, and the tensile strength and yield strength of the titanium alloy can be improved.

[0021] The powder hot isostatic pressing process of the embodiments of the present application is suitable for preparing α+β type titanium alloy and near-α type titanium alloy.

[0022] Most titanium alloys are classified according to the β stability coefficient (βs) , which refers to the sum of the concentration of each β stable element (such as molybdenum, vanadium, niobium, iron, etc.) in the alloy and the respective critical concentration ratio. When 0-0.07, it is an α type titanium alloy; when 0.07-0.25, it is a near-α type titanium alloy; when 0.25-1.0, it is generally referred to as an α+β type titanium alloy; when 1.0-2.8, it is referred to as a near-β type titanium alloy; and when greater than 2.8, it is referred to as a β type titanium alloy.

[0023] In some embodiments, in the step S2 described above, the first heating gradient is 5-10 ℃ / min (for example, it can be 5 ℃ / min, 6 ℃ / min, 7 ℃ / min, 8 ℃ / min, 9 ℃ / min, or 10 ℃ / min, etc.), the second heating gradient is 2-5 ℃ / min (for example, it can be 2 ℃ / min, 3 ℃ / min, 4 ℃ / min, or 5 ℃ / min, etc.), and the third heating gradient is 1-2 ℃ / min (for example, it can be 1 ℃ / min or 2 ℃ / min, etc.).

[0024] In some embodiments, in the step S2 described above, the ratio of the first target pressure to the second target pressure is 1:1-3.

[0025] By controlling the ratio of the first target pressure to the second target pressure to be 1:1-3, the grain size and the uniformity of the titanium alloy can be regulated on the basis of complete densification of the powder, the composition segregation can be reduced, the composition uniformity can be ensured, and the process stability and economy can be considered.

[0026] In some embodiments, in the step S2, the first pressure increasing gradient is 0.5-2 MPa / min, and the second pressure increasing gradient is 0.5-1 MPa / min.

[0027] In some embodiments, in the step S3, the cooling of the titanium alloy ingot to the fourth target temperature comprises: cooling the titanium alloy ingot from the third target temperature to 800 ℃ at a cooling rate of 8-10 ℃ / min, and then cooling the titanium alloy ingot from 800 ℃ to the fourth target temperature at a cooling rate of 3-5 ℃ / min.

[0028] In some embodiments, during the holding and pressure maintaining, the fluctuation range of the furnace temperature of the hot isostatic pressing equipment is maintained within a preset temperature threshold range, and the fluctuation range of the furnace pressure is maintained within a preset pressure threshold range. The preset temperature range is generally-5 ℃-5 ℃. The preset pressure range is generally-1 MPa-1 MPa.

[0029] In the process of preparing the titanium alloy by powder hot isostatic pressing, scientific and reasonable 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 the titanium alloy powder under high-temperature and high-pressure conditions is complex and dynamically changing, the present application adopts multiple sensors for partitioning and stepwise temperature and pressure increasing control to ensure the stability, uniformity and synchronism of the temperature field and pressure field distribution in the furnace of the hot isostatic pressing equipment.

[0030] In the hot isostatic pressing process, the hot isostatic pressing furnace, the inert gas (generally argon) in the furnace and the sealing jacket form a three-layer wrapping structure from the outside to the inside (as shown in Figure 1 The temperature of the sealing jacket is continuously heated and increased with the increase of the temperature of the hot isostatic pressing furnace in the temperature increasing and holding stage, which is an unstable heat exchange process among the hot isostatic pressing furnace, the inert gas in the furnace and the sealing jacket.

[0031] As an example, please refer to Figure 1 The first temperature sensors A, B, C and D (the first sensor group) can be respectively arranged at the four top corners of the inner wall of the hot isostatic pressing furnace to monitor the temperature change of the inner wall of the hot isostatic pressing furnace; the second temperature sensors E and F (the second sensor group) can be arranged in the interior of the hot isostatic pressing furnace to monitor the temperature change of the inert gas in the furnace; and the third temperature sensors G and H (the third sensor group) can be arranged on the outer surface of the sealing jacket to monitor the temperature change of the outer surface of the sealing jacket.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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%.

[0042] 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.

[0043] In some embodiments, in step S1 above, the sheath is a low-carbon steel sheath.

[0044] 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.

[0045] Example 1 This embodiment provides a method for preparing titanium alloys by hot isostatic pressing of powder, including the following steps: 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.

[0046] 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.

[0047] 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.

[0048] Example 2 This embodiment provides a method for preparing titanium alloy components by hot isostatic pressing of powder, including the following steps: 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.

[0049] 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.

[0050] 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.

[0051] Example 3 This embodiment provides a method for preparing titanium alloy components by hot isostatic pressing of powder, including the following steps: 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.

[0052] 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.

[0053] 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.

[0054] Comparative Example 1 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%).

[0055] Comparative Example 2 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%).

[0056] Comparative Example 3 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, except that: 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.

[0057] Comparative Example 4 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, except that: 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.

[0058] Comparative Example 5 This comparative example provides a method for preparing titanium alloy components by hot isostatic pressing of powder, comprising the following steps: 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.

[0059] 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.

[0060] 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.

[0061] Comparative Example 6 This comparative example provides a method for preparing titanium alloy components by hot isostatic pressing of powder, comprising the following steps: 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.

[0062] 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.

[0063] 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.

[0064] Comparative Example 7 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.

[0065] Comparative Example 8 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.

[0066] 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.

[0067] The test items are as follows: (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.

[0068] (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".

[0069] (3) Fracture toughness: 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): (1) In the formula, HV is Vickers hardness, a is the half-length of the indentation diagonal, c is the half-length of the crack, and KIC is the fracture toughness value.

[0070] Table 1

[0071] 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.

[0072] 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.

[0073] 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 / 2 The 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.

[0074] 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.

[0075] 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 by, The method comprises the following steps: Mixing fine-grained near-spherical titanium alloy powder and coarse-grained near-spherical titanium alloy powder according to a preset mass ratio to obtain mixed powder, and loading the mixed powder into a capsule, and then performing vibration, degassing and sealing treatment to obtain a sealed capsule; Placing the sealed capsule in a hot isostatic pressing device, starting to increase the pressure to a first target pressure at a first pressure increasing gradient when the temperature is increased to 80-90% of a first target temperature at a first temperature increasing gradient, maintaining the temperature and pressure for 0.5-3 hours, then increasing the temperature to a second target temperature at a second temperature increasing gradient while increasing the pressure to a second target pressure at a second pressure increasing gradient, maintaining the temperature and pressure for 1-2 hours, and then increasing the temperature to a third target temperature at a third temperature increasing gradient while maintaining the second target pressure, and maintaining the temperature and pressure for 0.5-1 hours to obtain a titanium alloy ingot, wherein the first target temperature is 400-550 ℃, the second target temperature is 600-750 ℃, and the third target temperature is 850-950 ℃. Cooling the titanium alloy ingot to a fourth target temperature and maintaining the temperature for 0.5-1 hours, then increasing the temperature to a fifth target temperature and maintaining the temperature for 0.5-1 hours, and then water quenching to room temperature, and removing the capsule to obtain a titanium alloy component, wherein the fourth target temperature is 700-750 ℃, and the fifth target temperature is 950-1050 ℃.

2. The method of claim 1, wherein the method is characterized by: The first temperature increasing gradient is 5-10 ℃ / min, the second temperature increasing gradient is 2-5 ℃ / min, and the third temperature increasing gradient is 1-2 ℃ / min.

3. The method of claim 1, wherein the powder hot isostatic pressing titanium alloy is controlled at a high temperature and a high pressure. The ratio of the first target pressure to the second target pressure is 1:1-3.

4. The method according to claim 1, wherein the first pressure increasing gradient is 0.5-2 MPa / min, and the second pressure increasing gradient is 0.5-1 MPa / min.

5. The method of claim 1, wherein the method further comprises: controlling the temperature of the powder bed to a temperature of about 1000 °C to about 1200 °C. Cooling the titanium alloy ingot to a fourth target temperature, comprising: Cooling the titanium alloy ingot from the third target temperature to 800 ℃ at a cooling rate of 8-10 ℃ / min, and then cooling the titanium alloy ingot from 800 ℃ to the fourth target temperature at a cooling rate of 3-5 ℃ / min.

6. The method of claim 1, wherein the method further comprises: During the temperature and pressure maintaining process, the fluctuation range of the furnace temperature of the hot isostatic pressing device is maintained within a preset temperature threshold range, and the fluctuation range of the furnace pressure is maintained within a preset pressure threshold range.

7. The method of claim 1, wherein the powder hot isostatic pressing titanium alloy is controlled at a high temperature and a high pressure. 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.

8. The method of claim 1 or 7, wherein the powder hot isostatic pressing titanium alloy is controlled at a high temperature and a high pressure. 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.

9. The method of claim 1, wherein the powder hot isostatic pressing titanium alloy is controlled at a high temperature and a high pressure. The tap density of the mixed powder in the sealed capsule is greater than or equal to 65%.

10. The method of claim 1, wherein the powder hot isostatic pressing titanium alloy is controlled at a high temperature and a high pressure. The capsule is a low-carbon steel capsule.

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