A heat treatment method for improving the strength and toughness matching of WSTi6421 titanium alloy

Abstract

The present application belongs to the technical field of titanium alloy processing, and relates to a heat treatment method for improving the strength and toughness matching of WSTi6421 titanium alloy. The heat treatment method determines the heat treatment holding time of the test material by measuring and drawing the temperature rising curves of different thickness positions of the test material; at the same time, three-stage segmented temperature rising and uniform temperature holding treatment are adopted to reduce the organizational differences; the test material is also subjected to aging heat treatment when being returned to the furnace to control the size of the lamellar alpha phase, so that the high strength, high plasticity and high toughness matching of the WSTi6421 titanium alloy is realized, and the heat treatment process of the titanium alloy with toughness index requirements can be popularized.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy processing technology, and relates to a heat treatment method for improving the strength and toughness matching of WSTi6421 titanium alloy. Background Technology

[0002] High-strength and high-toughness titanium alloy is a titanium alloy with a tensile strength of 1200 MPa. After proper heat treatment, it can meet the requirements of tensile strength > 1200 MPa, elongation > 6%, and fracture toughness > 80 MPa·m. 1 / 2 It possesses high room temperature strength and plasticity, excellent impact toughness, fracture toughness and fatigue properties, making it a titanium alloy material with excellent comprehensive performance that can be used in aerospace structural components.

[0003] High-strength and high-toughness WSTi6421 titanium alloy is quite sensitive to heat treatment processes, and it is difficult to achieve a "high strength-high toughness" match using only conventional heat treatment processes. Typically, to obtain high strength and high toughness, titanium alloy materials undergo β-heat treatment, such as solution treatment in the β-phase region followed by air cooling to room temperature, and then annealing or aging in the two-phase region. During this β-heat treatment, the alloying elements in the titanium alloy dissolve into the titanium matrix through heating, forming a homogeneous solid solution. In this process, the alloying elements undergo a solid solution reaction with the titanium matrix, thereby changing the material's microstructure and properties. Moreover, the longer the β-phase solution treatment time, the more complete the solid solution reaction; however, the longer the titanium alloy is held in the β-phase region, the larger the β grain size will be, thus reducing the material's plasticity. Furthermore, due to the low thermal conductivity of titanium alloys, for large-sized titanium alloy materials, the edges reach the set temperature first during heat treatment, while the core requires a longer holding time to reach the set temperature. This leads to uncontrolled growth of the β-grain size at the edges due to prolonged heating, resulting in greater differences in microstructure and properties across different locations, potentially even failing to meet requirements. To reduce this difference, a conventional method is to employ a two-stage heat treatment approach. For example, heating below the phase transformation point and holding for a long time to achieve a uniform temperature, followed by heating to the β-phase region and holding for a short time to prevent excessive β-grain size and reduced plasticity. However, because the phase transformation points of different types of titanium alloys vary significantly (e.g., TC4 titanium alloy typically has a phase transformation point of 990℃, while WSTi6421 titanium alloy typically has a phase transformation point of 880℃), and the thermal conductivity of different titanium alloys varies considerably at different temperatures, there is currently no clear method for determining the heating temperature and holding time for each stage in a two-stage heat treatment approach for different types of titanium alloys.

[0004] Furthermore, after β heat treatment, during the cooling process, when the temperature drops to an appropriate level, alloying elements precipitate from the solid solution, forming new phases such as precipitated phases or supersaturated phases. Additionally, during cooling, when the temperature drops below the phase transformation temperature of the titanium alloy, lamellar α phases (α′) begin to grow from the grain boundaries. The thickness of the lamellar α phase is related to the cooling rate; a faster cooling rate results in a smaller thickness and lower fracture toughness, but increased plasticity; a slower cooling rate results in a larger thickness and higher fracture toughness, but decreased plasticity. Obtaining a stable heat treatment regime for high-strength and high-toughness WSTi6421 titanium alloy, achieving a balance of ultra-high strength, high plasticity, and high toughness, and ensuring consistent microstructure and properties, is crucial for the application of this titanium alloy in the aerospace industry. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a heat treatment method to improve the strength and toughness matching of WSTi6421 titanium alloy.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This heat treatment method for improving the strength and toughness matching of WSTi6421 titanium alloy involves measuring and plotting the heating curves at different thicknesses of the test material, and simultaneously employing three-stage segmented heating and uniform holding treatments to reduce microstructure differences. The heat treatment cooling process uses a furnace aging method to control the size of the lamellar α phase, thereby achieving a balance of high strength, high plasticity, and high toughness in WSTi6421 titanium alloy.

[0008] Furthermore, the above heat treatment method specifically includes the following steps:

[0009] Step 1: Measure and plot the temperature rise curve using WSTi6421 titanium alloy test material;

[0010] Step 2: Based on the heating curve, select the temperature points for the three-stage segmented heating and record the temperature arrival time of the thermocouples. Calculate the temperature arrival time difference between different locations when reaching the selected temperature.

[0011] Step 3: Determine the three-stage uniform temperature and holding time for the WSTi6421 titanium alloy test material, and perform uniform temperature holding.

[0012] Step 4: After uniform heating and heat preservation, remove the WSTi6421 titanium alloy test material from the furnace and air cool it. Transfer the air-cooled WSTi6421 titanium alloy test material to a heat treatment furnace and heat preservation for 2 to 6 hours. After removing it from the furnace, air cool it to room temperature to complete the preparation of high-strength, high-plasticity and high-toughness WSTi6421 titanium alloy.

[0013] Furthermore, in step 1, the WSTi6421 titanium alloy test material is a square block, and its heating temperature is 40°C above the phase transformation point temperature of the WSTi6421 titanium alloy.

[0014] Furthermore, the WSTi6421 titanium alloy test material is placed in the heating furnace at room temperature; or, the WSTi6421 titanium alloy test material is placed in the heating furnace when the temperature is raised to a specified temperature, wherein the specified temperature is 100°C below the phase transformation point temperature of the WSTi6421 titanium alloy.

[0015] Furthermore, step 1 specifically includes:

[0016] Step 1.1: Machining mounting holes at designated locations on the WSTi6421 titanium alloy test material for mounting temperature measuring thermocouples. The designated locations are determined based on the dimensions of the test material.

[0017] Step 1.2: The WSTi6421 titanium alloy test material can be placed in the heating furnace at room temperature; or, it can be placed in the heating furnace when the temperature is raised to a specified temperature, wherein the specified temperature is 100°C below the phase transformation point temperature of the WSTi6421 titanium alloy.

[0018] Step 1.3: Set the heating temperature of the furnace to 40°C above the phase change point temperature, start heating and record the temperature value detected by the thermocouple every 1 to 2 minutes.

[0019] Step 1.4: Plot the heating curves of the WSTi6421 titanium alloy test material at different depths based on temperature and time.

[0020] Furthermore, in step 1.1, determining the thermocouple installation position based on the dimensions of the test sample specifically involves:

[0021] If the maximum cross-sectional dimension D of the WSTi6421 titanium alloy test material is between 40mm and 80mm, then select two installation positions: the edge and the core.

[0022] If the maximum cross-sectional dimension D of the WSTi6421 titanium alloy test material is greater than 80 mm and less than or equal to 160 mm, then select three installation positions: edge, D / 4, and core.

[0023] Furthermore, step 2 specifically includes:

[0024] On the heating curve, nine temperature points were selected: when the temperature reached 80°C, 60°C, 40°C, and 20°C below the phase transition temperature; when the temperature reached the phase transition temperature; and when the temperature reached 10°C, 20°C, 30°C, and 40°C above the phase transition temperature. The temperature arrival times of the thermocouples at different positions on the WSTi6421 titanium alloy test material were recorded.

[0025] If the maximum cross-sectional dimension D of the WSTi6421 titanium alloy test material is between 40 mm and 80 mm, then calculate the temperature arrival time difference between the edge and the core at the selected temperature points; if the maximum cross-sectional dimension D of the WSTi6421 titanium alloy test material is greater than 80 mm and less than or equal to 160 mm, then calculate the temperature arrival time difference between the edge and the core, the edge and D / 4, and D / 4 and the core at the selected temperature points.

[0026] Furthermore, step 3 specifically includes:

[0027] Step 3.1: Determine the first-stage uniform temperature insulation temperature T1 and the first-stage uniform temperature insulation time t1:

[0028] After obtaining the temperature arrival time difference between the edge and D / 4 at the selected 9 temperature points, if the temperature arrival time difference of the currently selected temperature point is greater than or equal to 1.1 times the temperature arrival time difference of the previous selected temperature point, the previous temperature point is selected as the first-level uniform temperature insulation temperature T1.

[0029] The time difference between the edge and center of the WSTi6421 titanium alloy test material reaching the first-stage uniform temperature holding temperature T1 is recorded as t. a The first-stage uniform temperature holding time t1 is divided according to the different maximum cross-sectional dimensions D of the WSTi6421 titanium alloy test material: 1) If D is between 40mm and 80mm, then t1 = t a 2) If D is greater than 80mm and less than or equal to 160mm, t1 = t a ×(D / 80);

[0030] Step 3.2: Determine the second-stage uniform temperature insulation temperature T2 and the second-stage uniform temperature insulation time t2:

[0031] T2 was selected as 5°C below the phase transformation temperature; the edge and center of the WSTi6421 titanium alloy test material were compared when the phase transformation temperature T was reached. β The time difference from temperature to temperature is denoted as t. b The second-stage uniform temperature holding time t2 is divided according to the different maximum cross-sectional dimensions D of the WSTi6421 titanium alloy test material: 1) If D is between 40mm and 80mm, then t2 = t b 2) If D is greater than 80mm and less than or equal to 160mm, t2 = t b ×(D / 80);

[0032] Step 3.3: Select 40°C above the phase change point temperature as the third-stage uniform temperature holding temperature T3, and the third-stage uniform temperature holding time t3 is 30min~40min.

[0033] Furthermore, the air cooling time in step 4 is 20 min to 30 min.

[0034] Furthermore, the heating temperature of the heat treatment furnace in step 4 is 700°C.

[0035] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0036] This invention determines the appropriate heat treatment holding time for the test material by measuring and plotting the heating curves at different thicknesses. Simultaneously, it employs a three-stage segmented heating and uniform holding process to reduce microstructural differences. The heat treatment cooling process utilizes a furnace aging method to control the size of the lamellar α-phase, thereby achieving a balance of high strength, high plasticity, and high toughness in WSTi6421 titanium alloy. This heat treatment method can be extended to the heat treatment of titanium alloys with toughness requirements. Attached Figure Description

[0037] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0039] Figure 1 A flowchart of a heat treatment method for improving the strength-toughness matching of WSTi6421 titanium alloy provided by the present invention;

[0040] Figure 2 This is a temperature rise curve plotted when a test sample with a size of 160 mm is heated to 920°C in Example 1 of the present invention.

[0041] Figure 3 This is a projection image of the WTi6421 titanium alloy part prepared in Example 1 of the present invention. Detailed Implementation

[0042] Exemplary embodiments will be described in detail below. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of methods consistent with some aspects of the present invention as detailed in the appended claims.

[0043] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0044] Example 1

[0045] Using the heat treatment method provided in this embodiment to improve the strength-toughness ratio of WSTi6421 titanium alloy, WSTi6421 titanium alloy parts are prepared. See [link to relevant documentation]. Figure 3Its specific dimensions are 400mm (length) × 400mm (width) × 160mm (thickness), and its weight is approximately 92kg. The dimensions of the test material used are 160mm (length) × 160mm (width) × 160mm (thickness), and the specific steps of the heat treatment method are as follows:

[0046] Step 1: Use WSTi6421 titanium alloy test material to measure and plot the heating curve (i.e., the curve of temperature versus time during the heating process), specifically:

[0047] Step 1.1: Drill mounting holes in the center of the test material to install temperature measuring thermocouples. Use three thermocouples to test the temperature at three locations: the edge, D / 4, and the center of the test material.

[0048] Step 1.2: Use a heating furnace with an effective heating zone heat uniformity of less than or equal to ±8℃ and heat to 800℃; after the furnace reaches the temperature, load the test material (with thermocouple) into the heating furnace;

[0049] Step 1.3: Set the heating temperature of the furnace to 920℃, start heating and record the temperature detected by the three thermocouples every 1 minute;

[0050] Step 1.4: Stop recording when the test temperature of the core thermocouple reaches 920℃, and plot the temperature and time curves of the three thermocouples;

[0051] Step 2: On the measured temperature and time curves, select the temperature at which the temperature reaches the phase transition point (T). β The phase transition point temperature (T) is reached at the following temperatures: 80℃, 60℃, 40℃, and 20℃. β Generally at 880℃), and reaching the phase transition point temperature (T β Nine temperature points were recorded at 10℃, 20℃, 30℃, and 40℃. The arrival times of thermocouples at different locations on the test material were recorded. The arrival time differences between the edge and D / 4, D / 4 and the center, and the edge and the center at the selected temperature points were calculated. Specific data are shown in Table 1 below.

[0052] Table 1. Temperature arrival time difference at different locations of the test sample.

[0053]

[0054]

[0055] Step 3.1: Determine the first-stage uniform temperature insulation temperature T1 and the first-stage uniform temperature insulation time t1.

[0056] According to the data in Table 1, when the phase change point is 880℃, the time difference from edge-D / 4 to temperature is 37min. 37 divided by 34 is approximately equal to 1.1. Therefore, the first stage uniform temperature holding temperature T1 of the heat treatment of the part should be set to 860℃.

[0057] According to the data in Table 1, at the edge-core location, when the first-stage uniform temperature is 860℃, the time difference to reach the temperature is 43 min, and the first-stage uniform temperature holding time t1 = 43 min × (160 / 80) = 86 min.

[0058] Step 3.2: Determine the second-stage uniform temperature insulation temperature T2 and the second-stage uniform temperature insulation time t2:

[0059] The second-stage uniform temperature insulation temperature for 160mm thick parts is set to 875℃.

[0060] According to the data in Table 1, when the phase change point is 880℃, the time difference between the edge and the core reaching the temperature is 46min, t2=46min×(D / 80)=92min, that is, the second stage of uniform temperature holding time t2 of the heat treatment of the part should be set to 92min;

[0061] Step 3.3: The third-stage uniform temperature holding temperature for the 160mm thick part is set to 920℃, and the holding time is 30min;

[0062] Step 4.1: After the 160mm thick parts have completed the third stage of uniform temperature preservation, they should be removed from the furnace and air-cooled for 30 minutes. In order to ensure that the material is cooled evenly in all positions, the material needs to be placed on a hollow material rack at least 500mm above the ground.

[0063] Step 4.2: Transfer the 160mm thick part after air cooling to a heat treatment furnace heated to 700℃, hold for 6 hours, and then air cool to room temperature after taking it out of the furnace. This completes the preparation of a WSTi6421 titanium alloy part with dimensions of 400mm (length) × 400mm (width) × 160mm (thickness).

[0064] Example 2

[0065] Using the heat treatment method provided in this embodiment to improve the strength-toughness ratio of WSTi6421 titanium alloy, WSTi6421 titanium alloy parts were prepared. The specific dimensions were 600mm (length) × 400mm (width) × 80mm (thickness), and the weight was approximately 53kg. The experimental material used had dimensions of 80mm (length) × 80mm (width) × 80mm (thickness), and the specific steps of the heat treatment method are as follows:

[0066] Step 1: Use WSTi6421 titanium alloy test material to measure and plot the heating curve (i.e., the curve of temperature versus time during the heating process), specifically:

[0067] Step 1.1: Drill a mounting hole in the center of the test material to install a temperature measuring thermocouple. Use two thermocouples to test the temperature at the edge and center of the test material.

[0068] Step 1.2: Use a heating furnace with an effective heating zone heat uniformity of less than or equal to ±8℃ and heat to 800℃; after the furnace reaches the temperature, load the test material (with thermocouple) into the heating furnace;

[0069] Step 1.3: Set the heating temperature of the furnace to 920℃, start heating and record the temperature detected by the two thermocouples every 1 minute;

[0070] Step 1.4: Stop recording when the test temperature of the core thermocouple reaches 920℃, and plot the temperature and time curves of the two thermocouples;

[0071] Step 2: On the measured temperature and time curves, select the temperature at which the temperature reaches the phase transition point (T). β The phase transition point temperature (T) is reached at the following temperatures: 80℃, 60℃, 40℃, and 20℃. β Generally at 880℃), and reaching the phase transition point temperature (T β Nine temperature points were recorded at 10℃, 20℃, 30℃, and 40℃. The arrival times of thermocouples at different locations on the test material were recorded, and the difference in arrival times between the edge and the center at the selected temperature points was calculated. Specific data are shown in Table 2 below.

[0072] Table 2. Temperature arrival time differences at different locations of the test sample.

[0073]

[0074]

[0075] Step 3.1: Determine the first-stage uniform temperature insulation temperature T1 and the first-stage uniform temperature insulation time t1.

[0076] According to the data in Table 2, when the phase change point is 880℃, the time difference between the edge and the core reaching the temperature is 35min. 35 divided by 32 is approximately equal to 1.1. Therefore, the first stage uniform temperature holding temperature T1 of the heat treatment of the part should be set to 860℃.

[0077] According to the data in Table 2, at the edge-to-center location, when the first-stage uniform temperature is 860℃, the time difference to reach the temperature is 32 minutes, and the first-stage uniform temperature holding time is t1 = 32 minutes.

[0078] Step 3.2: Determine the second-stage uniform temperature insulation temperature T2 and the second-stage uniform temperature insulation time t2:

[0079] The second-stage uniform temperature insulation temperature for 160mm thick parts is set to 875℃.

[0080] According to the data in Table 2, when the phase change point is 880℃, the time difference between the edge and the core reaching the temperature is 35min. Therefore, the second stage of uniform temperature holding time t2 in the heat treatment of the part should be set to 35min.

[0081] Step 3.3: The third-stage uniform temperature holding temperature for 80mm thick parts is set to 920℃, and the holding time is 30min;

[0082] Step 4.1: After the third stage of uniform temperature preservation is completed for the 80mm thick parts, air cool them for 30 minutes after removing them from the furnace. In order to ensure that the material is cooled evenly in all positions, the material needs to be placed on a hollow material rack at least 500mm above the ground.

[0083] Step 4.2: Transfer the air-cooled 80mm thick part to a heat treatment furnace heated to 700℃ and hold for 6 hours. After removing it from the furnace, air-cool it to room temperature to complete the preparation of a WSTi6421 titanium alloy part with dimensions of 600mm (length) × 400mm (width) × 80mm (thickness).

[0084] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0085] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A heat treatment method for improving the strength-toughness balance of WSTi6421 titanium alloy, characterized in that, Temperature curves at different thicknesses of the test material were plotted by measurement, and three-stage segmented heating and uniform temperature holding treatment were adopted to reduce the difference in microstructure. The heat treatment cooling process adopts a furnace aging method to control the size of the lamellar α phase, thereby achieving a balance of high strength, high plasticity and high toughness in WSTi6421 titanium alloy; The heat treatment method specifically includes the following steps: Step 1: Measure and plot the temperature rise curve using WSTi6421 titanium alloy test material; Step 2: Based on the heating curve, select the temperature points for the three-stage segmented heating and record the temperature arrival time of the thermocouples. Calculate the temperature arrival time difference between different locations when reaching the selected temperature. Step 3: Determine the three-stage uniform temperature and holding time for the WSTi6421 titanium alloy test material, and perform uniform temperature holding. Step 4: After uniform heating and heat preservation, remove the WSTi6421 titanium alloy test material from the furnace and air cool it. Transfer the air-cooled WSTi6421 titanium alloy test material to a heat treatment furnace and heat preservation for 2h~6h. After removing it from the furnace, air cool it to room temperature to complete the preparation of high-strength, high-plasticity and high-toughness WSTi6421 titanium alloy. Step 2 specifically involves: On the heating curve, nine temperature points were selected: when the temperature reached 80°C, 60°C, 40°C, and 20°C below the phase transition temperature; when the temperature reached the phase transition temperature; and when the temperature reached 10°C, 20°C, 30°C, and 40°C above the phase transition temperature. The temperature arrival times of the thermocouples at different positions on the WSTi6421 titanium alloy test material were recorded. If the maximum cross-sectional dimension D of the WSTi6421 titanium alloy test material is between 40 mm and 80 mm, then calculate the temperature arrival time difference between the edge and the core at the selected temperature points; if the maximum cross-sectional dimension D of the WSTi6421 titanium alloy test material is greater than 80 mm and less than or equal to 160 mm, then calculate the temperature arrival time difference between the edge and the core, the edge and D / 4, and D / 4 and the core at the selected temperature points. Step 3 specifically includes: Step 3.1: Determine the first-stage uniform temperature insulation temperature T1 and the first-stage uniform temperature insulation time t1: After obtaining the temperature arrival time difference between the edge and D / 4 at the selected 9 temperature points, if the temperature arrival time difference of the current selected temperature point is greater than or equal to 1.1 times the temperature arrival time difference of the previous selected temperature point, the previous temperature point is selected as the first-level uniform temperature insulation temperature T1. The time difference between the edge and center of the WSTi6421 titanium alloy test material reaching the first-stage uniform temperature holding temperature T1 is recorded as t. a The first-stage uniform temperature holding time t1 is divided according to the different maximum cross-sectional dimensions D of the WSTi6421 titanium alloy test material: 1) If D is between 40mm and 80mm, then t1 = t a 2) If D is greater than 80mm and less than or equal to 160mm, t1 = t a ×(D / 80) Step 3.2: Determine the second-stage uniform temperature insulation temperature T2 and the second-stage uniform temperature insulation time t2: T2 was selected as 5°C below the phase transformation temperature; the edge and center of the WSTi6421 titanium alloy test material were compared when the phase transformation temperature T was reached. β The time difference from temperature to temperature is denoted as t. b The second-stage uniform temperature holding time t2 is divided according to the different maximum cross-sectional dimensions D of the WSTi6421 titanium alloy test material: 1) If D is between 40mm and 80mm, then t2 = t b 2) If D is greater than 80mm and less than or equal to 160mm, t2 = t b ×(D / 80) Step 3.3: Select 40°C above the phase change point temperature as the third-stage uniform temperature holding temperature T3, and the third-stage uniform temperature holding time t3 is 30min~40min.

2. The heat treatment method for improving the strength-toughness matching of WSTi6421 titanium alloy according to claim 1, characterized in that, In step 1, the WSTi6421 titanium alloy test material is a square block, and its heating temperature is 40°C above the phase transformation point temperature of the WSTi6421 titanium alloy.

3. The heat treatment method for improving the strength-toughness matching of WSTi6421 titanium alloy according to claim 2, characterized in that, The WSTi6421 titanium alloy test material is placed in the heating furnace at room temperature; or, the WSTi6421 titanium alloy test material is placed in the heating furnace when the temperature is raised to a specified temperature, wherein the specified temperature is 100°C below the phase transformation point temperature of the WSTi6421 titanium alloy.

4. The heat treatment method for improving the strength-toughness matching of WSTi6421 titanium alloy according to claim 1, characterized in that, Step 1 specifically includes: Step 1.1: Machining mounting holes at designated locations on the WSTi6421 titanium alloy test material for mounting temperature measuring thermocouples. The designated locations are determined based on the dimensions of the test material. Step 1.2: The WSTi6421 titanium alloy test material can be placed in the heating furnace at room temperature; or, it can be placed in the heating furnace when the temperature is raised to a specified temperature, wherein the specified temperature is 100°C below the phase transformation point temperature of the WSTi6421 titanium alloy. Step 1.3: Set the heating temperature of the furnace to 40°C above the phase change point temperature, start heating and record the temperature value detected by the thermocouple every 1 to 2 minutes. Step 1.4: Plot the heating curves of the WSTi6421 titanium alloy test material at different depths based on temperature and time.

5. The heat treatment method for improving the strength-toughness matching of WSTi6421 titanium alloy according to claim 4, characterized in that, In step 1.1, determining the installation position of the thermocouple based on the dimensions of the test sample is specifically as follows: If the maximum cross-sectional dimension D of the WSTi6421 titanium alloy test material is between 40mm and 80mm, then select two installation positions: the edge and the core. If the maximum cross-sectional dimension D of the WSTi6421 titanium alloy test material is greater than 80 mm and less than or equal to 160 mm, then select three installation positions: edge, D / 4, and core.

6. The heat treatment method for improving the strength-toughness matching of WSTi6421 titanium alloy according to claim 1, characterized in that, The air cooling time in step 4 is 20 min to 30 min.

7. The heat treatment method for improving the strength-toughness balance of WSTi6421 titanium alloy according to any one of claims 1 to 6, characterized in that, The heating temperature of the heat treatment furnace in step 4 is 700℃.

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