Method for determining titanium alloy die forging parameters of basket weave structure with fragmented grain boundaries

Abstract

A method for determining the forging parameters of a titanium alloy with a basket weave structure having fragmented grain boundaries, which utilizes the law that the grain boundary precipitates in the titanium alloy precipitate prior to the intragranular precipitates, determines the forging process parameters based on experiments and numerical simulations, sets the pressing speed during the hot forging process according to the total stroke of the upper die pressing down during the forging process, and controls the pressing speed using a constant strain rate. The forging parameters of the titanium alloy with a basket weave structure having fragmented grain boundaries obtained by the present invention provide a scientific basis and a specific implementation method for formulating the forging process of the titanium alloy. The microstructure of the titanium alloy forgings prepared by this method presents a basket weave structure with fragmented grain boundaries, having a good match of room temperature tensile, high temperature tensile, fracture toughness, high cycle fatigue, high temperature creep rupture, and high temperature creep properties, and having the characteristics of strong operability and high accuracy, scientifically formulating the forging process parameters of the titanium alloy forgings, reducing the process development cost, and improving the quality of the titanium alloy forgings.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy forging, in particular to a method for determining die forging parameters of a titanium alloy with a basket structure having a broken grain boundary based on an interrupted heat-insulating test and finite element numerical simulation. Background Art

[0002] Titanium alloys have the characteristics of low density, high specific strength, good toughness, excellent fatigue and creep properties, etc., and are widely used in the manufacturing of aviation structural parts, engine discs, etc. Whether it is a structural part or a disc, it needs to serve for a long time in a harsh environment, and requires high comprehensive performance, including a good match of strength, plasticity, toughness, fatigue, durability, creep and other properties. However, in order for titanium alloys to obtain the above good comprehensive properties, it is necessary to precisely control the microstructure of titanium alloys. If titanium alloys can obtain a basket structure with broken grain boundaries, the forgings can meet the requirements of a good match of strength, plasticity, toughness, fatigue, durability, creep and other properties.

[0003] However, titanium alloy is a difficult-to-deform material. Its forging process needs to be carried out at high temperature. In addition, the processing window of titanium alloy is narrow. It is very difficult to accurately control the microstructure of the forging to present a basket structure with broken grain boundaries within a narrow processing window at high temperature. This requires accurate forging process formulation to reduce the economic and time costs consumed by repeated trial and error. The basket structure with broken grain boundaries in titanium alloy is obtained by using the law that the grain boundary precipitation phase precipitates before the intracrystalline precipitation phase. The mold temperature, workpiece temperature, and pressing speed are reasonably set to make the grain boundary precipitation phase precipitate in the early stage of the forging process. During the forging process, the grain boundary precipitation phase will undergo greater deformation, and the grain boundary precipitation phase will be broken; the intracrystalline precipitation phase is precipitated at the end of forging or after deformation. During the forging process, the intracrystalline precipitation phase will undergo very little deformation or no deformation, and the intracrystalline precipitation phase will present a basket shape. Therefore, in order to formulate reasonable mold temperature, workpiece temperature, and pressing speed, it is necessary to clarify the precipitation temperature range of the grain boundary precipitation phase and the intracrystalline precipitation phase, as well as the time required for the workpiece temperature to drop to the mold. The present invention provides a method for formulating the die temperature, workpiece temperature and pressing speed of titanium alloy die forging by interrupting the heat preservation test in combination with the finite element numerical simulation. The method can provide a reliable basis for formulating the process parameters of the titanium alloy die forging, so that the microstructure of the titanium alloy presents a basket structure with broken grain boundaries, thereby ensuring that the titanium alloy has excellent comprehensive mechanical properties.

[0004] The national invention patent with the patent authorization number "CN 101804441 B" discloses a "near isothermal forging method for TC17 two-phase titanium alloy disc forgings". This method sets the die temperature to 10-20°C below the phase transition point of the TC17 titanium alloy, the billet temperature to 20-60°C above the phase transition point of the TC17 titanium alloy, and the temperature is set at 0.001-0.01s -1Forging is carried out at a strain rate to obtain an ideal basket weave structure and high performance. The national invention patent with the publication number "CN 115041616 A" discloses a "method for preparing a β-forged integral bladed disk forging of TC19 titanium alloy with high efficiency and low cost". This method sets the blank temperature to be 20 - 50 °C above the phase transformation point of this TC19 titanium alloy, and the die temperature to be 30 - 60 °C below the phase transformation point of this TC19 titanium alloy, and forges at a constant strain rate of 0.005 - 0.05 s -1 to obtain a basket weave structure with fine and uniform original β grain size and good weaving of lamellar α phase within the grains. The national invention patent with the authorized announcement number "CN112024800B" discloses a "method for β hot die forging of a large-sized integral bladed disk forging of TC17 titanium alloy". This invention sets the blank temperature for β hot die forging to be 30 - 50 °C above the phase transformation point of this TC17 titanium alloy, and the die temperature to be 550 - 600 °C. The forged disk has high strength, plasticity, toughness, and fatigue life. The national invention patent with the authorized announcement number "CN 110976747 B" discloses a "method for β-forging an integral bladed disk of TC17 alloy". This invention sets the roughing temperature to be 25 - 45 °C above the phase transformation point of this TC17 titanium alloy, and the die temperature to be 30 - 50 °C below the phase transformation point of this TC17 titanium alloy. The forged integral bladed disk has an ideal basket weave structure and excellent mechanical properties matching it. The national invention patent with the application publication number "CN 113369428 A" discloses a "method for preparing a large-sized β-forged integral bladed disk forging of TC17 titanium alloy". This invention heats the preform to 20 - 40 °C above the phase transformation point of this TC17 titanium alloy and the die temperature to 20 - 60 °C below the phase transformation point of this TC17 titanium alloy during the forging process, and forges at a constant strain rate of 0.001 - 0.01 s -1 to obtain an integral bladed disk with uniform microstructure, tensile strength that can meet the design requirements, and excellent strength-toughness matching. The national invention patent with the authorized announcement number "CN 101480689 B" discloses a "near-isothermal forging method for a two-phase titanium alloy disk-shaped forging". This invention sets the blank temperature to be 20 - 60 °C above the phase transformation point of the titanium alloy and the die temperature to be 10 - 20 °C below the phase transformation point of the titanium alloy during the forging process, and forges at a constant strain rate of 0.001 - 0.01 s -1The forging is performed at a constant strain rate, and the forging is subjected to post-forging heat treatment to obtain a relatively ideal basketweave structure and high performance. The national invention patent with the patent authorization announcement number "CN104762576B" discloses a "method for preparing medium-sized and ultra-long bars of TC18 titanium alloy with full basketweave structure". The method obtains medium-sized and ultra-long bars of TC18 titanium alloy with full basketweave structure through the steps of blank forging, upsetting forging, precision forging, high-temperature solid solution, low-temperature aging pretreatment, α+β zone deformation heat treatment, aging, etc. The national invention patent with the patent authorization announcement number "CN 109865787 B" discloses "a forging method for obtaining TC18 forgings with uniform basketweave structure". The method keeps the TC18 blank at 10 to 30°C above the phase transformation point, and then forges the blank at 30 to 50°C below the phase transformation point to obtain the basketweave structure. The national invention patent with the patent application publication number "CN111235504 A" discloses "a production process for titanium alloy thick plates with basket mesh structure". The invention prepares titanium alloy thick plates with uniform and fine basket mesh structure and performance indicators that meet technical standards through one-time hot rolling, β heat treatment and two-time hot rolling. The national invention patent with the patent authorization announcement number "CN 111318581 B" discloses "a method for manufacturing large-size rings of titanium alloy with basket mesh structure". The invention obtains rings with basket mesh structure through upsetting, punching and shaping at 20-50℃ below the phase transformation point, expanding at 20-50℃ below the phase transformation point, ring tying at 25-80℃ above the phase transformation point, and solid solution + aging double heat treatment. None of the above patents give the selection method and basis of the forging process such as die temperature, billet temperature and forging speed of titanium alloy during forging. At present, the selection of forging process mainly depends on the experience of technicians, which will affect the rationality of the selection of disc forging process. Moreover, the basket structure obtained by the above patent does not contain the characteristics of broken grain boundaries. The continuous grain boundary precipitation phase will reduce the plasticity of the titanium alloy, and in severe cases will cause the occurrence of β brittleness, which is very unfavorable to the mechanical properties of the titanium alloy. Summary of the invention

[0005] In order to overcome the problems existing in the prior art that the selection of die temperature, workpiece temperature and pressing speed in the titanium alloy die forging process has no scientific basis, which will affect the rationality of the forging process selection; the morphology of the basket structure does not include the characteristics of the broken grain boundary, resulting in unstable microstructure morphology and mechanical properties of the forging, a method for determining the die forging parameters of titanium alloys with a basket structure having broken grain boundaries is invented.

[0006] The specific process of the present invention is:

[0007] Step 1, interrupt the insulation test:

[0008] An interrupted thermal insulation test was carried out on titanium alloy to obtain interrupted thermal insulation samples with different thermal insulation conditions.

[0009] During the interrupted heat preservation test, the temperatures of multiple titanium alloy specimens are raised to 10 - 50 °C above the phase transformation point of the titanium alloy and kept warm for 20 - 60 min. After the heat preservation ends, each titanium alloy specimen is cooled to 10 - 200 °C below the phase transformation point of the titanium alloy at a rate of 10 - 50 °C / s and kept warm for 10 - 30 min; after the heat preservation ends, each specimen is cooled to room temperature at a cooling rate of 50 - 200 °C / s.

[0010] Step 2, determine the precipitation temperature ranges of grain boundary precipitates and intragranular precipitates:

[0011] Prepare metallographic specimens of the specimens, and determine the precipitation temperature ranges of grain boundary precipitates and intragranular precipitates by observing the microstructural morphology of the titanium alloy specimens with interrupted heat preservation.

[0012] When determining the precipitation temperature ranges of grain boundary precipitates and intragranular precipitates, judge the precipitation conditions of grain boundary precipitates and intragranular precipitates in each titanium alloy specimen at each test temperature based on the microstructural morphology of each titanium alloy specimen, and obtain the precipitation temperature ranges of grain boundary precipitates and intragranular precipitates.

[0013] The precipitation temperature range of the grain boundary precipitates is the temperature range from the start of precipitation of the grain boundary precipitates to the point where the size of the grain boundary precipitates no longer increases; the precipitation temperature range of the intragranular precipitates is the temperature range from the start of precipitation of the intragranular precipitates to the point where the size of the intragranular precipitates no longer changes.

[0014] Step 3, determine the die temperature and workpiece temperature of die forging:

[0015] When determining the die temperature and workpiece temperature of hot die forging, set the die temperature of hot die forging based on the precipitation temperature ranges of grain boundary precipitates and intragranular precipitates of the titanium alloy; set the workpiece temperature according to the phase transformation point of the titanium alloy.

[0016] The die temperature is the temperature below the phase transformation point of the titanium alloy, and is set based on the obtained precipitation temperature ranges of grain boundary precipitates and intragranular precipitates of the titanium alloy. The basis for setting the die temperature is that a large amount of grain boundary precipitates precipitate and a small amount of intragranular precipitates exist at this temperature.

[0017] The workpiece temperature is 10 - 50 °C above the phase transformation point of the titanium alloy.

[0018] Step 4, calculate the time required for the workpiece temperature to drop to the die temperature:

[0019] Simulate the cooling process of the workpiece temperature dropping to the die temperature through finite element method, and obtain the time t required for this cooling process.

[0020] Step 5, determine the die pressing speed during die forging:

[0021] According to the total stroke when the upper die presses down after contacting the workpiece during the hot die forging process and the time required for the temperature of the workpiece to drop to the die temperature obtained in step 4, determine the pressing speed of the die during the hot die forging process; the pressing speed is controlled by a constant strain rate, and this strain rate is used as the control speed for the die to press down.

[0022] The calculation method of the constant strain rate is as follows: ε = ln(1 - b);

[0023] In the formula is the constant strain rate obtained, ε is the strain of the forging during the die forging process, b is the deformation amount of the forging during the die forging process, and t is the time obtained in step 4.

[0024] Compared with the prior art, the beneficial effects obtained by the present invention are as follows:

[0025] The present invention is simple to operate, highly operable, and accurate. By using the method provided by the present invention, the forging process parameters of titanium alloy forgings can be scientifically formulated, including die temperature, workpiece temperature, and pressing speed, reducing the process development cost, improving the quality of titanium alloy forgings, and meeting the requirements of microstructures and mechanical properties. Based on the interrupted heat preservation test of titanium alloy, the precipitation temperature ranges of grain boundary precipitation phases and intragranular precipitation phases of this titanium alloy are obtained. According to the obtained precipitation temperature ranges of grain boundary precipitation phases and intragranular precipitation phases, the die temperature is formulated; the workpiece temperature is set according to the phase transformation point of the titanium alloy. To ensure that the titanium alloy forging presents a basket-like structure with fragmented grain boundaries, the temperature of the workpiece should be 10 - 50 °C above the phase transformation point; based on the set die temperature and workpiece temperature, use finite element numerical simulation to calculate the time required for the workpiece to cool down to the die temperature. According to the total stroke when the upper die contacts the workpiece and presses down during the forging process, set the pressing speed during the hot die forging process, and the pressing speed is controlled by a constant strain rate. This method utilizes the law that grain boundary precipitation phases precipitate prior to intragranular precipitation phases in titanium alloy, and reasonably sets the forging process parameters based on experiments and numerical simulations, enabling grain boundary precipitation phases to precipitate in the early stage of the forging process. During the forging process, the grain boundary precipitation phases will undergo large deformations and present a fragmented shape; enabling intragranular precipitation phases to precipitate at the end of the forging or after the deformation ends. During the forging process, the intragranular precipitation phases will undergo very small deformations or no deformations and present a basket-like shape. The present invention provides a scientific basis and specific implementation method for the formulation of titanium alloy die forging processes. The microstructures of the titanium alloy forgings prepared by this method present a basket-like structure with fragmented grain boundaries, having good matching of room temperature tensile, high temperature tensile, fracture toughness, high cycle fatigue, high temperature creep resistance, and high temperature creep properties. Description of the Drawings

[0026] Figure 1 Are the microstructures of TC17 alloy after interrupted heat preservation tests at different temperatures; among them Figure 1a is the microstructure of the TC17 alloy at 20 °C below the phase transformation point, Figure 1 b is the microstructure of the TC17 alloy at 50 °C below the phase transformation point, Figure 1 c is the microstructure of the TC17 alloy at 100 °C below the phase transformation point, Figure 1 d is the microstructure of the TC17 alloy at 200 °C below the phase transformation point.

[0027] Figure 2 is the finite element simulation result of the temperature of the TC17 alloy workpiece dropping to the die temperature; among them Figure 2 a is the sampling position of P1 - P9, Figure 2 each curve in b is the cooling curve of the points at positions P1 - P9.

[0028] Figure 3 is the microstructure of the TC17 alloy forging.

[0029] Figure 4 is the microstructure of the Ti2AlNb alloy after interrupted heat preservation tests at different temperatures; among them Figure 4 a is the microstructure of the Ti2AlNb alloy at 100 °C below the B2 phase transformation point, Figure 4 b is the microstructure of the Ti2AlNb alloy at 30 °C below the B2 phase transformation point, Figure 4 c is the microstructure of the Ti2AlNb titanium alloy at 60 °C below the B2 phase transformation point, Figure 4 d is the microstructure of the Ti2AlNb titanium alloy at 200 °C below the B2 phase transformation point.

[0030] Figure 5 is the finite element simulation result of the temperature of the Ti2AlNb alloy workpiece dropping to the die temperature; among them Figure 5 a is the sampling position of P1 - P9, Figure 5 each curve in b is the cooling curve of the points at positions P1 - P9.

[0031] Figure 6 is the microstructure of the Ti2AlNb alloy forging.

[0032] Figure 7 is the flow chart of the present invention. Detailed implementation manners

[0033] Example 1

[0034] The present invention is a method for determining the die forging parameters of a titanium alloy with a basket weave structure having fragmented grain boundaries, and its technical solution will be described in detail through 4 examples.

[0035] The specific process of the present invention is as follows:

[0036] Step 1, interrupted heat preservation test:

[0037] Interrupted heat preservation tests were carried out on titanium alloys to obtain interrupted heat preservation specimens under different heat preservation conditions.

[0038] During the interrupted heat preservation test, the temperatures of multiple titanium alloy specimens were raised to 10 - 50 °C above the phase transformation point of the titanium alloy and heat preservation was carried out for 20 - 60 min. After the heat preservation ended, each titanium alloy specimen was cooled to 10 - 200 °C below the phase transformation point of the titanium alloy at a rate of 10 - 50 °C / s and heat preservation was carried out for 10 - 30 min; after the heat preservation ended, each specimen was cooled to room temperature at a cooling rate of 50 - 200 °C / s.

[0039] The titanium alloys are TC17 alloy, Ti2AlNb alloy, β-CEZ alloy and Ti-B19 alloy.

[0040] Step 2, determine the precipitation temperature ranges of grain boundary precipitates and intragranular precipitates:

[0041] Metallographs of each titanium alloy specimen after the interrupted heat preservation test were prepared by conventional methods to obtain the microstructural morphologies of each specimen of each titanium alloy. Based on the microstructural morphologies, the precipitation situations of grain boundary precipitates and intragranular precipitates in each titanium alloy specimen at each test temperature were judged, and the precipitation temperature ranges of grain boundary precipitates and intragranular precipitates were obtained.

[0042] The precipitation temperature range of the grain boundary precipitates is the temperature range from the start of precipitation of the grain boundary precipitates to the point where the size of the grain boundary precipitates no longer increases; the precipitation temperature range of the intragranular precipitates is the temperature range from the start of precipitation of the intragranular precipitates to the point where the size of the intragranular precipitates no longer changes.

[0043] The precipitation temperature ranges of the grain boundary precipitates and the precipitation temperature ranges of the intragranular precipitates of the obtained four titanium alloy specimens are summarized in Table 1;

[0044] Among them, the precipitation temperature range of the intragranular precipitates is divided into the range with a small amount of intragranular precipitates and the range with a large amount of intragranular precipitates, and the specific temperature ranges of the four titanium alloys are summarized in Table 1.

[0045] The precipitation temperature range of the grain boundary precipitates of the TC17 alloy specimen is 20 - 100 °C below the phase transformation point. Within this range, the grain boundary precipitates increase with the decrease of the interrupted heat preservation temperature; the precipitation temperature range of the intragranular precipitates is 50 - 200 °C below the phase transformation point, among which the intragranular precipitates are in a small amount in the range of 50 - 100 °C, and a large amount of this precipitate intragranularly precipitates in the range of 100 - 200 °C.

[0046] The precipitation temperature range of the grain boundary precipitation phase in the Ti2AlNb alloy specimen is 10 - 60 °C below the phase transformation point. Within this range, the amount of grain boundary precipitation phase increases as the interrupted holding temperature decreases; the precipitation temperature range of the intragranular precipitation phase is 30 - 200 °C below the phase transformation point. Among them, the intragranular precipitation phase is in a small amount in the range of 30 - 60 °C, and a large amount of this precipitation phase precipitates intragranularly in the range of 60 - 200 °C.

[0047] The precipitation temperature range of the grain boundary precipitation phase in the β-CEZ alloy specimen is 40 - 90 °C below the phase transformation point. Within this range, the amount of grain boundary precipitation phase increases as the interrupted holding temperature decreases; the precipitation temperature range of the intragranular precipitation phase is 70 - 200 °C below the phase transformation point. Among them, the intragranular precipitation phase is in a small amount in the range of 70 - 90 °C, and a large amount of this precipitation phase precipitates intragranularly in the range of 90 - 200 °C.

[0048] The precipitation temperature range of the grain boundary precipitation phase in the Ti-B19 alloy specimen is 30 - 110 °C below the phase transformation point. Within this range, the amount of grain boundary precipitation phase increases as the interrupted holding temperature decreases; the precipitation temperature range of the intragranular precipitation phase is 60 - 200 °C below the phase transformation point. Among them, the intragranular precipitation phase is in a small amount in the range of 60 - 110 °C, and a large amount of this precipitation phase precipitates intragranularly in the range of 110 - 200 °C.

[0049] Step 3, determine the die temperature and workpiece temperature of hot die forging:

[0050] Set the die temperature of hot die forging according to the precipitation temperature ranges of the grain boundary precipitation phase and intragranular precipitation phase of the titanium alloy; set the workpiece temperature according to the phase transformation point of the titanium alloy.

[0051] The die temperature is the temperature below the phase transformation point of this titanium alloy, and is set according to the obtained precipitation temperature ranges of the grain boundary precipitation phase and intragranular precipitation phase of the titanium alloy. The basis for setting the die temperature is that a large amount of grain boundary precipitation phase precipitates and a small amount of intragranular precipitation phase exists at this temperature. The specific values of the die temperatures set for the four titanium alloys are listed in Table 1.

[0052] The workpiece temperature is 10 - 50 °C above the phase transformation point of these four titanium alloys. The specific values of the workpiece temperatures set for the four titanium alloys are listed in Table 1.

[0053] Step 4, calculate the time required for the workpiece temperature to drop to the die temperature:

[0054] Simulate the cooling process of the workpiece temperature dropping to the die temperature through Deform finite element numerical simulation software. Using the default die forging heat transfer coefficient in the software, calculate the time t required for the workpiece temperature to drop to the die temperature. The specific times t for the four titanium alloys are summarized in Table 1.

[0055] Step 5, determine the die pressing speed during die forging:

[0056] Based on the total stroke when the upper die presses down after contacting the workpiece during hot die forging and the time required for the temperature of the workpiece to drop to the die temperature obtained in step 4, determine the pressing speed of the die during hot die forging; the pressing speed is controlled by a constant strain rate, and this strain rate is used as the control speed for the die to press down.

[0057] The calculation method of the constant strain rate is as follows: ε = ln(1 - b);

[0058] In the formula, is the constant strain rate obtained, ε is the strain of the forging during die forging, b is the deformation amount of the forging during die forging, and t is the time obtained in step 4. The specific values of the four titanium alloys are summarized in Table 1.

[0059] Table 1 Technical parameters and process conditions of each example:

[0060]

[0061]

[0062] To verify the rationality of the present invention, TC17 and Ti2AlNb alloys are selected for die forging, conventional heat treatment is carried out, and the microstructure and mechanical properties are detected.

[0063] According to the conventional heat treatment system of TC17 titanium alloy, the obtained TC17 titanium alloy forgings are heat-treated. According to "Chinese Engineering Materials Encyclopedia", the heat treatment system of TC17 titanium alloy is 800°C / 4h / WQ + 630°C / 6h / AC; the heat treatment of the TC17 titanium alloy forgings is completed.

[0064] Observe the microstructure of the heat-treated TC17 titanium alloy forgings, and the microstructure morphology is as Figure 3 shown, and test the mechanical properties of the TC17 titanium alloy forgings. The mechanical properties include room temperature tensile, high temperature tensile, fracture toughness, high cycle fatigue, high temperature creep and high temperature creep properties. The test results are shown in Table 2.

[0065] According to the conventional heat treatment system of Ti2AlNb alloy, the forgings after die forging are heat-treated. By referring to the literature, the heat treatment system of Ti2AlNb alloy is 960°C / 2h / WQ + 780°C / 24h / AC; observe the microstructure of the heat-treated forgings and test the mechanical properties. The mechanical properties include room temperature tensile, high temperature tensile, fracture toughness, high cycle fatigue, high temperature creep and high temperature creep properties. The microstructure morphology is as Figure 6 shown, and the test results of the mechanical properties are shown in Table 3.

[0066] Table 2 shows the mechanical properties of TC17 alloy forgings:

[0067]

[0068]

[0069] Table 3 shows the mechanical properties of Ti2AlNb alloy forgings:

[0070]

Claims

1. A method for determining the forging parameters of a titanium alloy with a basket weave structure having broken grain boundaries, characterized in that, The specific process is as follows: Step 1, interrupted heat preservation test: Perform an interrupted heat preservation test on the titanium alloy to obtain interrupted heat preservation specimens under different heat preservation conditions; Step 2, determine the precipitation temperature ranges of grain boundary precipitates and intragranular precipitates: Prepare metallographic specimens of the specimens, and determine the precipitation temperature ranges of grain boundary precipitates and intragranular precipitates by observing the microstructural morphology of the interrupted heat preservation specimens of the titanium alloy; Step 3, determine the die temperature and workpiece temperature for hot forging: When determining the die temperature and workpiece temperature for hot forging, set the die temperature for hot forging according to the precipitation temperature ranges of grain boundary precipitates and intragranular precipitates of the titanium alloy; set the workpiece temperature according to the phase transformation point of the titanium alloy; The die temperature is the temperature below the phase transformation point of the titanium alloy, and is set according to the obtained precipitation temperature ranges of grain boundary precipitates and intragranular precipitates of the titanium alloy; the basis for setting the die temperature is: at this temperature, a large amount of grain boundary precipitates precipitate and a small amount of intragranular precipitates; The workpiece temperature is 10 - 50 °C above the phase transformation point of the titanium alloy; Step 4, calculate the time required for the workpiece temperature to drop to the die temperature: Simulate the cooling process of the workpiece temperature dropping to the die temperature through Deform finite element numerical simulation software, and obtain that the time required for this cooling process is 610 s; Step 5, determine the die pressing speed during the forging process: Based on the total stroke of the upper die pressing down after contacting the workpiece during the hot forging process and the time required for the workpiece temperature to drop to the die temperature obtained in Step 4, determine the die pressing speed during the hot forging process; the pressing speed is controlled by a constant strain rate, and this strain rate is used as the control speed for the die pressing; The calculation method of the constant strain rate: ε = |ln(1 - b)|; In the formula, is the constant strain rate obtained, ε is the strain of the forging during the die forging process, b is the deformation amount of the forging during the die forging process, and t is the time obtained in step 4.

2. The method for determining the titanium alloy die forging parameters of a basket weave structure with broken grain boundaries according to claim 1, characterized in that, During the interrupted heat preservation test, raise the temperatures of multiple titanium alloy specimens to 30 °C above the phase transformation point of the titanium alloy and keep them warm for 30 min; after the heat preservation ends, cool each titanium alloy specimen to 10 - 200 °C below the phase transformation point of the titanium alloy at a speed of 45 °C / s and keep it warm for 15 min; after the heat preservation ends, cool each specimen to room temperature at a cooling speed of 100 °C / s.

3. The method for determining the titanium alloy die forging parameters of the basket weave structure with broken grain boundaries as claimed in claim 1, wherein, When determining the precipitation temperature ranges of grain boundary precipitates and intragranular precipitates, judge the precipitation conditions of grain boundary precipitates and intragranular precipitates in each titanium alloy specimen at each test temperature based on the microstructural morphology of each titanium alloy specimen, and obtain the precipitation temperature ranges of grain boundary precipitates and intragranular precipitates.

4. The method for determining the titanium alloy die forging parameters of a basket weave structure with broken grain boundaries as claimed in claim 3, characterized in that, The precipitation temperature range of the grain boundary precipitates is the temperature range from the start of precipitation of the grain boundary precipitates to the point where the size of the grain boundary precipitates no longer increases; the precipitation temperature range of the intragranular precipitates is the temperature range from the start of precipitation of the intragranular precipitates to the point where the size of the intragranular precipitates no longer changes.

5. The method for determining the titanium alloy die forging parameters of a basket weave structure with broken grain boundaries as described in claim 1, wherein, The controlled speed of the mold pressing down is 0.0015 - 0.003 s -1 .

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