A method for determining TC17 titanium alloy blisk trans-beta forging process parameters

Abstract

A method for determining the forging process parameters of a TC17 titanium alloy integral bladed disk across the β-thrust, involves obtaining the strain and temperature distribution of the TC17 titanium alloy integral bladed disk after forming through finite element numerical simulation. The method obtains the strain and temperature change history of each part of the integral bladed disk, using the phase transformation point of TC17 titanium alloy as a boundary, to obtain the strain of each part of the integral bladed disk above and below the phase transformation point. This data is then compared with the established optimization targets of the TC17 titanium alloy integral bladed disk finite element numerical simulation. Through continuous adjustment, the optimized die temperature, billet temperature, and forging speed are finally obtained. This invention is convenient to operate and has good operability. It can monitor the metal flow, strain changes, and temperature changes during the forging process in real time, identify existing problems, and make targeted process adjustments. This can shorten the process development cycle, reduce process development costs, improve the quality of the integral bladed disk, and meet the microstructure and performance requirements.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy integral bladed disk forging technology, specifically a method for determining the process parameters for forging TC17 titanium alloy integral bladed disk across β. Background Technology

[0002] TC17 is a near-β-type two-phase titanium alloy with a nominal composition of Ti-5Al-2Sn-2Zr-4Mo-4Cr (wt.%). It possesses comprehensive properties such as low density, high specific strength, good thermal stability, and excellent fatigue performance, and has been widely used in the fabrication of disk components for high-performance aero-engines in my country. The integral bladed disk structure integrates the disk and blades into a single unit, eliminating tenons, mortises, locking devices, and other connecting devices. This not only effectively reduces weight but also avoids airflow losses, improving aerodynamic efficiency. Integral bladed disks include integral fan disks and integral compressor disks. Currently, TC17 titanium alloy integral bladed disks, prepared through trans-β forging, are widely used in fan disks and 1st to 3rd stage compressor disks for high-performance aero-engines in my country.

[0003] Integral titanium alloy bladed disks are rotating components in engines, requiring long-term operation in harsh environments with high temperature, high pressure, high speed, and high load. Therefore, they have high performance requirements. To achieve comprehensive performance requirements in terms of strength, plasticity, thermal stability, toughness, and fatigue resistance, TC17 titanium alloy integral bladed disks are commonly manufactured using the trans-β forging method. The temperature and speed settings during trans-β forging significantly affect the microstructure and properties. To meet high performance standards, the microstructure after forging must exhibit the following characteristics: the original β grains are elongated radially along the disk, with an aspect ratio of 2:1 to 5:1 to minimize β grain recrystallization; the α phase at grain boundaries is discontinuous, exhibiting an intermittent and bent distribution; and the intragranular α phase has a well-woven basket structure. To achieve the above organizational standards, the forging process standard for TC17 titanium alloy integral bladed disks specifies that the equivalent strain distribution in the effective area of ​​the forging should be between 0.6 and 1.7, the equivalent strain range above the phase transformation point should be 0.4 to 1.2, and the equivalent strain range below the phase transformation point should be 0.2 to 0.5. However, due to the narrow processing window of TC17 titanium alloy, accurately controlling the strain distribution above and below the phase transformation point of each part of the disk and obtaining a reasonable microstructure within this narrow processing window is very difficult. Using traditional trial-and-error methods would consume a significant amount of economic and time costs. The development of finite element numerical simulation technology provides an effective way to optimize forging process parameters. It can not only significantly reduce the economic and time costs of repeated trial and error, but also monitor metal flow, strain changes, and temperature changes during the forging process in real time, providing guidance for the formulation of forging process parameters.

[0004] An invention patent with publication number "CN 114818437 A" discloses an "optimization method for isothermal forging process of titanium alloy integral bladed disks". This method establishes a constitutive model of the influence of different compositions of TC17 titanium alloy on relative flow stress. The established constitutive model is imported into three-dimensional finite element numerical simulation software, and numerical simulations are performed on pre-forged and final forged parts under different forging temperatures, forging speeds, reduction amounts, and friction factors. The simulation diagrams of the distribution influence of stress, strain, and temperature fields in the pre-forged and final forged parts are obtained, and the process parameters for isothermal forging are optimized. This method improves the accuracy of the calculation results of macroscopic process parameters such as stress field, strain field, temperature field, and load of TC17 titanium alloy integral bladed disks. However, the innovation of this method in the numerical simulation process mainly lies in the establishment of the constitutive model and does not involve how to optimize the process parameters. A national invention patent with patent authorization publication number "CN110976747 B" discloses "a method for β-forging TC17 alloy integral bladed disks". This method involves machining a rough mold with an irregular cross-section to ensure that all parts of the forging achieve 50% to 70% deformation during the final die forging process, thereby effectively refining the original β grain size. However, this method does not address the distribution of deformation around the phase transformation point or how to control this distribution. Invention publication CN 113510207 A discloses a "Method for Manufacturing Large-Size Variable Cross-Section Integral Bladed Disk Forgings of TC17 Titanium Alloy". This method uses simulation to design the optimal theoretical forging blank and the optimal theoretical rough blank; it designs the final forging die based on the optimal theoretical forging blank and the pre-forging die based on the optimal theoretical rough blank. This method improves the deformation and uniformity of the integral bladed disk forging, expands the effective deformation range, and improves material utilization. However, this method does not address the strain distribution of the forging, the strain distribution values ​​around the phase transformation point, or methods for controlling these distributions. National invention patent CN 112024800 B discloses a "Method for β-hot forging of a large TC17 titanium alloy integral bladed disk forging". This method involves sequentially performing free forging, β-hot forging, and heat treatment on TC17 titanium alloy bars. By adjusting the processing parameters, the β-forging microstructure is further refined, improving the overall microstructure uniformity of the forging and obtaining a microstructure with good overall performance matching, ensuring performance consistency. However, this method does not address the strain distribution of the forging, the strain distribution values ​​above and below the phase transformation point, or the control methods. Invention CN 113369428 A discloses a "Method for preparing a large-size TC17 titanium alloy β-forged integral bladed disk forging". This method optimizes the heating method of the preform, the lubrication of the die and billet, and the cooling method after forging during the β-forging process of the TC17 titanium alloy integral bladed disk, obtaining a large-size integral bladed disk forging with good filling. The microstructure of each part of the forging is uniform, the tensile strength meets the design requirements, and the strength and toughness are excellently matched.However, this method does not address the strain distribution values ​​and control methods for different parts of the forging around the phase transformation point. A 2019 doctoral dissertation from Northwestern Polytechnical University, "Key Technologies and Engineering Applications of β-Isothermal Forging of TC17 Alloy Integral Bladed Disks," reported on the design of preforms for TC17 alloy integral bladed disks using finite element simulation, establishing a uniform strain distribution in the forging with a strain range of 0.7–2.0. However, this dissertation only optimized the shape of the preform to meet the strain distribution requirements, without addressing the strain distribution values ​​and control methods for different parts of the forging around the phase transformation point. The journal *Hot Working Technology* published a paper titled "Research on Isothermal β Forging Process of TC17 Alloy Integral Bladed Disks" in its September 2016 issue (Volume 45, Issue 17). This paper reported that the total equivalent strain during the final forging of TC17 alloy integral bladed disks was greater than 0.7, ensuring deformation of the billet both above and below the phase transformation point. The resulting microstructure did not allow for coarse, continuous, or network-like grain boundary α phases; primary β grains were flattened and deformed; the grain boundary α phases were deformed and discontinuous; and the aspect ratio of the intragranular acicular α phases was not less than 10:1. However, this paper only qualitatively described that the forging should deform both above and below the phase transformation point, without addressing the specific strain range above and below the phase transformation point, or how to control the strain distribution above and below the phase transformation point. The journal *Advances in Titanium Industry* published a paper titled "Optimization of β-Forging Process for TC17 Alloy Discs" in its June 2021 issue (Volume 38, Issue 3). This paper reported on optimizing the shape of the TC17 alloy preform using finite element simulation technology, eliminating high-strain bands and low-strain zones in the forging, improving the deformation uniformity, microstructure uniformity, and mechanical properties of the disc forging. However, this paper only optimized the preform shape and improved the deformation uniformity of the forging; it did not address the strain distribution values ​​and control methods around the phase transformation point in different parts of the forging. The journal *Forging Technology* published a paper titled "Numerical Simulation of Isothermal Forging Process and Influence of Process Parameters on TC17 Alloy Integral Bladed Disk" in its June 2017 issue (Volume 42, Issue 6). This paper used the finite element simulation software Deform-2D to numerically simulate the isothermal β-die forging process of TC17 titanium alloy integral bladed disk forgings. Based on the finite element simulation results, the blank size and process parameters of the forging were optimized. When the strain reached 0.75, the strength, plasticity, and fracture toughness of the integral bladed disk achieved an ideal match. However, this paper only optimized the shape of the preform, ensuring that the strain in each part of the final forging reached above 0.75, without addressing the strain distribution values ​​and control methods around the phase transformation point in each part of the forging. None of the technical solutions proposed in the aforementioned patents and papers include the strain distribution values ​​and control methods around the phase transformation point in each part of the forging. This will lead to difficulties in controlling the microstructure morphology of each part of the TC17 titanium alloy integral bladed disk, further affecting the stability of its mechanical properties. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, such as unclear strain distribution values ​​at the phase transformation point of different parts of the TC17 alloy integral bladed disk during forging, unclear control methods, and inability to effectively control reasonable microstructure, this invention proposes a method for determining the process parameters of TC17 titanium alloy integral bladed disk forging across β.

[0006] The specific process of this invention is as follows:

[0007] Step 1: Develop optimization objectives for the β-forging of the TC17 titanium alloy integral bladed disk:

[0008] The optimization objective of the finite element numerical simulation is that the equivalent strain of each part of the axial section of the integral bladed disk forging is in the range of 0.6 to 1.7, the equivalent strain above the phase transformation point is in the range of 0.4 to 1.2, and the equivalent strain below the phase transformation point is in the range of 0.2 to 0.5.

[0009] The axial section of the integral bladed disk forging is a section passing through the center of the circle along the height direction of the integral bladed disk. Since the integral bladed disk is an axisymmetric structure, the equivalent strain distribution on any axial section can represent the equivalent strain distribution of the integral bladed disk.

[0010] Step 2: Draw the mold and blank drawings for the TC17 titanium alloy integral bladed disk:

[0011] The mold has an axisymmetric structure, and during the simulation, the equivalent strain and temperature change of any axial section can represent the entire mold; the billet has an axisymmetric structure, and during the simulation, the equivalent strain and temperature change of any axial section can represent the entire bladed disk of the TC17 titanium alloy fan; two-dimensional diagrams of the mold and the billet are drawn respectively.

[0012] Step 3, Finite element numerical simulation of the TC17 titanium alloy integral bladed disk:

[0013] Finite element numerical simulation of the TC17 titanium alloy integral bladed disk was performed, and the equivalent strain distribution diagram of the integral bladed disk and the historical data of equivalent strain and temperature change of each part were exported.

[0014] Import the simulation files of the mold and the billet into the finite element numerical simulation software in sequence; set the initial simulation parameters, including mold temperature, billet temperature, and forging speed.

[0015] A shear friction model was adopted, with a friction coefficient of 0.3 and a heat transfer coefficient of 5 N / sec / mm / ℃. Finite element numerical simulation of the integral bladed disk of the TC17 titanium alloy fan was performed, and the equivalent strain distribution diagram of the integral bladed disk and the historical data of equivalent strain and temperature change at points P1 to P13 were obtained and exported.

[0016] The mold temperature is 10–80°C below the phase transformation point of the TC17 titanium alloy; the billet temperature is 10–60°C above the phase transformation point of the TC17 titanium alloy; and the forging speed is less than or equal to 5 mm / s.

[0017] The equivalent strain distribution diagram of the integral bladed disk is a two-dimensional diagram of the equivalent strain on the axial section of the integral bladed disk obtained by finite element numerical simulation; the various parts of the integral bladed disk are the position points of the integral bladed disk disk and blade body, and the position points are selected evenly on the integral bladed disk using conventional methods; the historical data of equivalent strain and temperature change are the data of equivalent strain and temperature change throughout the entire process from the start to the end of forging.

[0018] Step 4: Calculate the strain distribution values ​​of each part above and below the phase transition point:

[0019] Based on the derived equivalent strain and temperature change history data of each part, the historical data of equivalent strain change is divided into two parts: strain above the phase transformation point and strain below the phase transformation point, with the phase transformation point of the TC17 titanium alloy as the boundary.

[0020] The strain above the phase transformation point and the strain below the phase transformation point represent the degree of deformation of the TC17 titanium alloy above the phase transformation point and the degree of deformation below the phase transformation point, respectively.

[0021] Step 5, optimize forging parameters:

[0022] The forging parameters include die temperature, billet temperature, and forging speed.

[0023] The equivalent strain of the TC17 titanium alloy integral bladed disk obtained by simulation and the strain of each part above and below the phase transformation point are compared with the optimization target of finite element numerical simulation.

[0024] If all the equivalent strains are within the range of the optimization target, then the mold temperature, billet temperature, and forging speed meet the requirements; if any of the equivalent strains are outside the range of the optimization target, then the mold temperature, billet temperature, and forging speed are considered not to meet the requirements, and the mold temperature, billet temperature, and forging speed are adjusted to obtain new mold temperature, billet temperature, and forging speed.

[0025] Repeat step 3, and use the new mold temperature, billet temperature and forging speed to perform a new finite element numerical simulation of the TC17 titanium alloy integral bladed disk, to obtain a new equivalent strain distribution diagram of the integral bladed disk and historical data of equivalent strain and temperature change of each part.

[0026] Repeat step 4 to calculate the new strain distribution values ​​of each part above and below the phase transformation point, and compare the obtained new strain distribution values ​​of each part above and below the phase transformation point with the optimization target, and determine whether the mold temperature, billet temperature and forging speed meet the requirements based on the comparison results.

[0027] If the comparison results prove that the mold temperature, billet temperature, and forging speed meet the requirements, proceed to the next step; otherwise, continue to adjust the mold temperature, billet temperature, and forging speed, and repeat steps 3 and 4 until the mold temperature, billet temperature, and forging speed meet the requirements.

[0028] When all the equivalent strains are within the range of the optimization target, the current mold temperature value, billet temperature value, and forging speed value are the optimized forging parameters.

[0029] When adjusting the die temperature, billet temperature, and forging speed

[0030] The mold temperature is 10–80°C below the phase transformation point of TC17 titanium alloy, with an adjustment step of 5°C each time; the billet temperature is 10–60°C above the phase transformation point of TC17 titanium alloy, with an adjustment step of 5°C each time; the forging speed is ≤5mm / s, and is adjusted in steps of 0.5mm / s.

[0031] Adjustments can be made using a single variable, or two or three variables. The adjustment principle is as follows: when the strain above the phase transformation point is greater than the optimization target range, or the strain below the phase transformation point is less than the optimization target range, then decrease the die temperature, increase the billet temperature, or decrease the forging speed. When the strain above the phase transformation point is less than the optimization target range, or the strain below the phase transformation point is greater than the optimization target range, then increase the die temperature, decrease the billet temperature, or increase the forging speed.

[0032] To verify the effectiveness of the present invention, the process parameters were used to forge the TC17 titanium alloy integral bladed disk, and the microstructure of the integral bladed disk was observed and the mechanical properties of the integral bladed disk were tested.

[0033] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0034] This invention is convenient and easy to operate, enabling real-time monitoring of metal flow, strain changes, and temperature variations during the forging process. It allows for the identification of problems and targeted process adjustments, shortening the process development cycle, reducing development costs, and improving the overall quality of the impeller. This invention uses finite element numerical simulation to obtain the strain and temperature distribution of the TC17 titanium alloy integral impeller after forming. The equivalent strain of each part of the integral impeller is between 0.6 and 1.7, allowing the original β grains to elongate along the radius of the integral impeller to an aspect ratio of 2:1 to 5:1. Using the strain and temperature change history of each part of the integral impeller obtained from finite element simulation, and taking the phase transformation point of the TC17 titanium alloy as the boundary, the strain of each part of the integral impeller above and below the phase transformation point is calculated. The equivalent strain range above the phase transformation point is 0.4–1.2, which ensures that before the α phase precipitates, the β grains and grain boundaries deform, the β grains are elongated, and the grain boundaries become bent. The strain within the 0.4–1.2 range is insufficient to cause significant recrystallization of the β grains, resulting in few or no recrystallized β grains. Below the phase transformation point, the equivalent strain range is 0.2–0.5, allowing the β grains to continue to deform and elongate. The preferentially precipitated α phase at the grain boundaries is distributed in a bent and discontinuous manner at the bent grain boundaries, while the subsequently precipitated intragranular α phase undergoes almost no deformation, maintaining the basketweave structure. This invention clearly defines the distribution range of equivalent strain above and below the phase transformation point for various parts of the TC17 titanium alloy integral bladed disk during forging, and proposes a method for controlling the distribution of equivalent strain above and below the phase transformation point for various parts of the TC17 titanium alloy integral bladed disk using finite element numerical simulation. The microstructure of the TC17 titanium alloy integral bladed disk prepared by this invention is characterized by the original β grains being elongated radially to a ratio of 2:1 or more, with little or no β recrystallized grains, discontinuous α phase at grain boundaries, and intragranular α phase exhibiting a basket-like structure. It exhibits excellent mechanical properties and meets the required specifications.

[0035] This invention is simple to operate and highly operable, which can shorten the process development cycle, reduce the process development cost, improve the overall quality of the impeller, and meet the requirements of structure and performance. Attached Figure Description

[0036] Figure 1This diagram shows the equivalent strain distribution and sampling point locations for various parts of a TC17 fan integral bladed disk forging. A is the contour line with an equivalent strain of 0, B is the contour line with an equivalent strain of 0.167, C is the contour line with an equivalent strain of 0.333, D is the contour line with an equivalent strain of 0.5, E is the contour line with an equivalent strain of 0.667, F is the contour line with an equivalent strain of 0.833, G is the contour line with an equivalent strain of 1.0, and H is the contour line with an equivalent strain of 1.17. Lines I, J, K, L, M, N, O, and P are defined as follows: I is the contour line with an equivalent change of 1.33; J is the contour line with an equivalent change of 1.5; K is the contour line with an equivalent change of 1.67; L is the contour line with an equivalent change of 1.83; M is the contour line with an equivalent change of 2.0; N is the contour line with an equivalent change of 2.17; O is the contour line with an equivalent change of 2.33; and P is the contour line with an equivalent change of 2.5. Points P1 to P13 are the sampling points for subsequent analysis of equivalent strain and temperature change history.

[0037] Figure 2 The equivalent strain history of points P1 to P13 of a certain TC17 fan integral bladed disk forging is shown.

[0038] Figure 3 The temperature change history of points P1 to P13 of a certain TC17 fan integral bladed disk forging.

[0039] Figure 4 Microstructure of a certain TC17 fan integral bladed disk forging; among which Figure 4 a represents the microstructure at point P1. Figure 4 b represents the microstructure of point P2. Figure 4 c represents the microstructure of point P4. Figure 4 d represents the microstructure of point P5. Figure 4 e represents the microstructure of point P12. Figure 4 f represents the microstructure of point P13.

[0040] Figure 5 This diagram shows the equivalent strain distribution and sampling point locations for various parts of an integral bladed disk forging of a TC17 compressor. Contour lines are: A (equivalent strain 0), B (equivalent strain 0.25), C (equivalent strain 0.5), D (equivalent strain 0.75), E (equivalent strain 1.0), F (equivalent strain 1.25), G (equivalent strain 1.5), H (equivalent strain 1.75), I (equivalent strain 2.0), J (equivalent strain 2.25), and K (equivalent strain 2.5). Points P1 to P12 are the sampling points for subsequent analysis of equivalent strain and temperature change history.

[0041] Figure 6The equivalent strain history of points P1 to P12 of an integral bladed disk forging of a TC17 compressor.

[0042] Figure 7 The temperature change history of points P1 to P12 of an integral bladed disk forging of a TC17 compressor.

[0043] Figure 8 Microstructure of a certain TC17 compressor integral bladed disk forging; among which Figure 8 a represents the microstructure at point P1. Figure 8 b represents the microstructure of point P2. Figure 8 c represents the microstructure of point P3. Figure 8 d represents the microstructure of point P5. Figure 8 e represents the microstructure of point P9. Figure 8 f represents the microstructure of point P11.

[0044] Figure 9 This is a flowchart of the present invention. Detailed Implementation

[0045] This invention relates to a method for determining the cross-β forging process parameters of a TC17 titanium alloy integral bladed disk. The integral bladed disk includes integral fan bladed disks and integral compressor bladed disks.

[0046] Example 1

[0047] This embodiment describes a method for determining process parameters for the forging of an integral bladed disk of a TC17 titanium alloy fan across the β layer, based on finite element numerical simulation. The specific process is as follows:

[0048] Step 1: Develop optimization targets for the β-forging of the integral bladed disk of the TC17 titanium alloy fan.

[0049] The TC17 titanium alloy fan integral bladed disk was selected. Based on the microstructure requirements for a TC17 titanium alloy integral bladed disk with good comprehensive mechanical properties: the original β grains are elongated radially along the disk, resulting in an aspect ratio of 2:1 to 5:1; the microstructure of this integral bladed disk contains little or no β recrystallized grains, and the α phase at the grain boundaries is discontinuous, exhibiting a discontinuous and bent distribution, while the intragranular α phase has a well-woven basket structure. Finite element numerical simulation optimization objectives were formulated for the TC17 titanium alloy fan integral bladed disk.

[0050] The optimization objective of the finite element numerical simulation is that the equivalent strain of each part of the axial section of the integral bladed disk forging is in the range of 0.6 to 1.7, the equivalent strain above the phase transformation point is in the range of 0.4 to 1.2, and the equivalent strain below the phase transformation point is in the range of 0.2 to 0.5.

[0051] The axial section of the integral bladed disk forging is a section passing through the center of the circle along the height direction of the integral bladed disk. Since the integral bladed disk is an axisymmetric structure, the equivalent strain distribution on any axial section can represent the equivalent strain distribution of the integral bladed disk.

[0052] Step 2: Draw the mold and blank drawing for the integral bladed disk of the TC17 titanium alloy fan.

[0053] Based on the actual working conditions of the TC17 titanium alloy fan integral bladed disk cross-beam forging, and considering the axially symmetrical structural characteristics of the TC17 titanium alloy fan integral bladed disk mold and blank, two-dimensional drawings of the mold and blank were drawn using AutoCAD drawing software and exported as .dxf files.

[0054] The mold has an axisymmetric structure. During the simulation, the equivalent strain and temperature change of any axis section can represent the entire mold. Therefore, a two-dimensional diagram of the mold is drawn. The billet has an axisymmetric structure. During the simulation, the equivalent strain and temperature change of any axis section can represent the entire bladed disk of the TC17 titanium alloy fan. Therefore, a two-dimensional diagram of the billet is drawn.

[0055] Step 3: Finite element numerical simulation of the integral bladed disk of the TC17 titanium alloy fan.

[0056] Finite element numerical simulation was performed on the integral bladed disk of the TC17 titanium alloy fan, and the equivalent strain distribution diagram of the integral bladed disk and the historical data of equivalent strain and temperature change of each part were exported and obtained. The parts are points P1 to P13 on the equivalent strain distribution diagram.

[0057] Import the simulation files of the mold and the billet into the Deform finite element numerical simulation software in sequence; set the initial simulation parameters, including mold temperature, billet temperature, and forging speed; the mold temperature range is 10 to 80°C below the phase transformation point of the TC17 titanium alloy; the billet temperature range is 10 to 60°C above the phase transformation point of the TC17 titanium alloy; and the forging speed is within the range of less than or equal to 5 mm / s.

[0058] The mold temperature was set to 40°C below the phase transformation point of the TC17 titanium alloy, the billet temperature was set to 20°C above the phase transformation point of the TC17 titanium alloy, and the forging speed was set to 1.5 mm / s. Following conventional methods, a shear friction model was used with a friction coefficient of 0.3 and a heat transfer coefficient of 5 N / sec / mm / °C. Finite element numerical simulation of the integral bladed disk of the TC17 titanium alloy fan was performed. After the simulation, the equivalent strain distribution diagram of the integral bladed disk and the historical data of equivalent strain and temperature change at points P1 to P13 were obtained and exported.

[0059] The equivalent strain distribution diagram of the integral bladed disk is a two-dimensional diagram of the equivalent strain on the axial section of the integral bladed disk obtained by finite element numerical simulation; points P1 to P13 are the location points of the integral bladed disk disk and blade body, and the location points are selected evenly on the integral bladed disk according to conventional methods; the equivalent strain and temperature change history data are the equivalent strain and temperature change data throughout the entire process from the start to the end of forging.

[0060] Step 4: Calculate the strain distribution values ​​of each part above and below the phase transition point.

[0061] The aforementioned locations are points P1 to P12 on the equivalent strain distribution diagram.

[0062] Based on the derived equivalent strain and temperature change history data of points P1 to P13, the historical data of equivalent strain change is divided into two parts: strain above the phase transformation point and strain below the phase transformation point, with the phase transformation point of the TC17 titanium alloy as the boundary.

[0063] The strain above the phase transformation point and the strain below the phase transformation point represent the degree of deformation of the TC17 titanium alloy above the phase transformation point and the degree of deformation below the phase transformation point, respectively.

[0064] Step 5: Optimize forging parameters.

[0065] The parameters include mold temperature, billet temperature, and forging speed.

[0066] The equivalent strain of the integral bladed disk of the TC17 titanium alloy fan and the strain of points P1 to P13 above and below the phase transition point obtained by simulation are compared with the optimization target of finite element numerical simulation.

[0067] If all the equivalent strains are within the range of the optimization target, then the mold temperature, billet temperature and forging speed meet the requirements; if any of the equivalent strains are outside the range of the optimization target, then the mold temperature, billet temperature and forging speed are considered not to meet the requirements, and the mold temperature, billet temperature and forging speed are adjusted to obtain new mold temperature, billet temperature and forging speed.

[0068] The new mold temperature, billet temperature, and forging speed are set.

[0069] Repeat step 3, and use the new mold temperature, billet temperature and forging speed to perform a new finite element numerical simulation of the integral bladed disk of the TC17 titanium alloy fan, and obtain the new equivalent strain distribution diagram of the integral bladed disk and the historical data of equivalent strain and temperature change at points P1 to P13.

[0070] Repeat step 4 to calculate the new strain distribution values ​​of points P1 to P13 above and below the phase transformation point. Compare the obtained new strain distribution values ​​of points P1 to P13 above and below the phase transformation point with the optimization target, and determine whether the mold temperature, billet temperature and forging speed meet the requirements based on the comparison results.

[0071] If the comparison results prove that the mold temperature, billet temperature, and forging speed meet the requirements, proceed to the next step; otherwise, continue to adjust the mold temperature, billet temperature, and forging speed, and repeat steps 3 and 4 until the mold temperature, billet temperature, and forging speed meet the requirements.

[0072] The mold temperature range is 10–80°C below the phase transformation point of the TC17 titanium alloy, with an adjustment step of 5°C each time; the billet temperature range is 10–60°C above the phase transformation point of the TC17 titanium alloy, with an adjustment step of 5°C each time; the forging speed is adjusted in steps of 0.5 mm / s within a range of less than or equal to 5 mm / s.

[0073] Adjustments can be made using a single variable, or two or three variables. The adjustment principle is as follows: when the strain above the phase transformation point is greater than the optimization target range, or the strain below the phase transformation point is less than the optimization target range, then decrease the die temperature, increase the billet temperature, or decrease the forging speed. When the strain above the phase transformation point is less than the optimization target range, or the strain below the phase transformation point is greater than the optimization target range, then increase the die temperature, decrease the billet temperature, or increase the forging speed.

[0074] In this embodiment, the optimized forging process parameters for the TC17 titanium alloy fan integral bladed disk are: die temperature 30°C below the phase transformation point, billet temperature 30°C above the phase transformation point, and forging speed 1 mm / s. The equivalent strain distribution diagram on the axial section of the TC17 titanium alloy fan integral bladed disk forged using the optimized process obtained from simulation is shown below. Figure 1 As shown, the historical data of equivalent strain and temperature change at points P1 to P13 are as follows: Figure 2 and Figure 3 As shown in Table 1, the strains at points P1 to P13 above and below the phase transition point are as follows.

[0075] Table 1 shows the strain distribution of points P1 to P13 on a TC17 fan integral bladed disk forging above and below the phase transformation point.

[0076] Location strain above the phase transition point strain below the phase transition point Total strain P1 0.85 0.37 1.22 P2 1.11 0.48 1.59 P3 1.14 0.5 1.64 P4 0.78 0.34 1.12 P5 0.66 0.29 0.95 P6 0.69 0.3 0.99 P7 1.05 0.46 1.51 P8 0.72 0.32 1.04 P9 0.49 0.20 0.69 P10 0.65 0.28 0.93 P11 0.51 0.22 0.73 P12 1.07 0.46 1.53 P13 0.70 0.31 1.01

[0077] To verify the rationality of the process, the process parameters were used to forge a TC17 titanium alloy fan integral bladed disk, and microstructure observation and performance testing were performed. The microstructure of the integral bladed disk is as follows: Figure 4As shown in Table 2, the mechanical properties of the overall bladed disk are as follows.

[0078] Table 2 shows the test results of the mechanical properties of a certain TC17 fan integral bladed disk forging:

[0079]

[0080]

[0081] Example 2

[0082] This embodiment describes a method for determining process parameters for the forging of an integral bladed disk of a TC17 titanium alloy compressor across the β layer, based on finite element numerical simulation. The specific process is as follows:

[0083] Step 1: Develop optimization objectives for the β-forging of the integral bladed disk of the TC17 titanium alloy compressor.

[0084] The TC17 titanium alloy compressor integral bladed disk was selected. Based on the microstructure requirements for a TC17 titanium alloy integral bladed disk with good comprehensive mechanical properties: the original β grains are elongated radially along the disk, resulting in an aspect ratio of 2:1 to 5:1; the integral bladed disk has little or no β recrystallized grains, and the α phase at the grain boundaries is discontinuous, exhibiting a discontinuous and bent distribution, while the intragranular α phase has a well-woven basket structure. Finite element numerical simulation optimization objectives were formulated for the TC17 titanium alloy fan integral bladed disk.

[0085] The optimization objective of the finite element numerical simulation is that the equivalent strain of each part of the axial section of the integral bladed disk forging is in the range of 0.6 to 1.7, the equivalent strain above the phase transformation point is in the range of 0.4 to 1.2, and the equivalent strain below the phase transformation point is in the range of 0.2 to 0.5.

[0086] The axial section of the integral bladed disk forging is a section passing through the center of the circle along the height direction of the integral bladed disk. Since the integral bladed disk is an axisymmetric structure, the equivalent strain distribution on any axial section can represent the equivalent strain distribution of the integral bladed disk.

[0087] Step 2: Draw the mold and blank drawing for the integral bladed disk of the TC17 titanium alloy compressor.

[0088] Based on the actual working conditions of the TC17 titanium alloy compressor integral bladed disk spanning β forging, and considering the axisymmetric structural characteristics of both the TC17 titanium alloy compressor integral bladed disk mold and billet, two-dimensional drawings of the mold and billet were drawn using AutoCAD drawing software and exported as .dxf files.

[0089] The mold has an axisymmetric structure. During the simulation, the equivalent strain and temperature change of any axis section can represent the entire mold. Therefore, a two-dimensional diagram of the mold is drawn. The billet has an axisymmetric structure. During the simulation, the equivalent strain and temperature change of any axis section can represent the integral bladed disk of the TC17 titanium alloy compressor. Therefore, a two-dimensional diagram of the billet is drawn.

[0090] Step 3: Finite element numerical simulation of the integral bladed disk of the TC17 titanium alloy compressor.

[0091] Finite element numerical simulation was performed on the integral bladed disk of the TC17 titanium alloy fan, and the equivalent strain distribution diagram of the integral bladed disk and the historical data of equivalent strain and temperature change of each part were exported and obtained. The parts are points P1 to P12 on the equivalent strain distribution diagram.

[0092] Import the simulation files of the mold and the billet into the Deform finite element numerical simulation software in sequence; set the initial simulation parameters, including mold temperature, billet temperature, and forging speed; the mold temperature range is 10 to 80°C below the phase transformation point of the TC17 titanium alloy; the billet temperature range is 10 to 60°C above the phase transformation point of the TC17 titanium alloy; and the forging speed is within the range of less than or equal to 5 mm / s.

[0093] The mold temperature was set 50°C below the phase transformation point of the TC17 titanium alloy, the billet temperature was set 30°C above the phase transformation point, and the forging speed was set to 1.5 mm / s. Following conventional methods, a shear friction model was used with a friction coefficient of 0.3 and a heat transfer coefficient of 5 N / sec / mm / °C. Finite element numerical simulation of the integral bladed disk of the TC17 titanium alloy compressor was performed. After the simulation, the equivalent strain distribution diagram of the integral bladed disk and the historical data of equivalent strain and temperature change at points P1 to P12 were obtained and exported.

[0094] The equivalent strain distribution diagram of the integral bladed disk is a two-dimensional diagram of the equivalent strain on the axial section of the integral bladed disk obtained by finite element numerical simulation; the points P1 to P12 are the location points of the integral bladed disk disk and blade body, and the location points are selected evenly on the integral bladed disk according to conventional methods; the equivalent strain and temperature change history data are the equivalent strain and temperature change data from the beginning to the end of the forging process.

[0095] Step 4: Calculate the strain distribution values ​​of each part above and below the phase transition point.

[0096] The aforementioned locations are points P1 to P12 on the equivalent strain distribution diagram.

[0097] Based on the derived equivalent strain and temperature change history data of points P1 to P12, the historical data of equivalent strain change is divided into two parts: strain above the phase transformation point and strain below the phase transformation point, with the phase transformation point of the TC17 titanium alloy as the boundary.

[0098] The strain above the phase transformation point and the strain below the phase transformation point represent the degree of deformation of the TC17 titanium alloy above the phase transformation point and the degree of deformation below the phase transformation point, respectively.

[0099] Step 5: Optimize forging parameters.

[0100] The parameters include mold temperature, billet temperature, and forging speed.

[0101] The equivalent strain of the integral bladed disk of the TC17 titanium alloy compressor obtained by simulation and the strain of points P1 to P12 above and below the phase transition point are compared with the optimization target of finite element numerical simulation.

[0102] If all the equivalent strains are within the range of the optimization target, then the mold temperature, billet temperature and forging speed meet the requirements; if any of the equivalent strains are outside the range of the optimization target, then the mold temperature, billet temperature and forging speed are considered not to meet the requirements, and the mold temperature, billet temperature and forging speed are adjusted to obtain new mold temperature, billet temperature and forging speed.

[0103] The new mold temperature, billet temperature, and forging speed are set.

[0104] Repeat step 3, and use the new mold temperature, billet temperature and forging speed to perform a new finite element numerical simulation of the integral bladed disk of the TC17 titanium alloy fan, and obtain the new equivalent strain distribution diagram of the integral bladed disk and the historical data of equivalent strain and temperature change at points P1 to P13.

[0105] Repeat step 4 to calculate the new strain distribution values ​​of points P1 to P12 above and below the phase transformation point. Compare the obtained new strain distribution values ​​of points P1 to P12 above and below the phase transformation point with the optimization target, and determine whether the mold temperature, billet temperature and forging speed meet the requirements based on the comparison results.

[0106] If the comparison results prove that the mold temperature, billet temperature, and forging speed meet the requirements, proceed to the next step; otherwise, continue to adjust the mold temperature, billet temperature, and forging speed, and repeat steps 3 and 4 until the mold temperature, billet temperature, and forging speed meet the requirements.

[0107] The mold temperature range is 10–80°C below the phase transformation point of the TC17 titanium alloy, with an adjustment step of 5°C each time; the billet temperature range is 10–60°C above the phase transformation point of the TC17 titanium alloy, with an adjustment step of 5°C each time; the forging speed is adjusted in steps of 0.5 mm / s within a range of less than or equal to 5 mm / s.

[0108] Adjustments can be made using a single variable, or two or three variables. The adjustment principle is as follows: when the strain above the phase transformation point is greater than the optimization target range, or the strain below the phase transformation point is less than the optimization target range, then decrease the die temperature, increase the billet temperature, or decrease the forging speed. When the strain above the phase transformation point is less than the optimization target range, or the strain below the phase transformation point is greater than the optimization target range, then increase the die temperature, decrease the billet temperature, or increase the forging speed.

[0109] In this embodiment, the optimized forging process parameters for the TC17 titanium alloy compressor integral bladed disk are: die temperature 40°C below the phase transformation point, billet temperature 30°C above the phase transformation point, and forging speed 0.5 mm / s. The equivalent strain distribution diagram on the axial section of the TC17 titanium alloy compressor integral bladed disk forged using the optimized process obtained from simulation is shown below. Figure 5 As shown, the historical data of equivalent strain and temperature change at points P1 to P12 are as follows: Figure 6 and Figure 7 As shown in Table 3, the strains at points P1 to P12 above and below the phase transition point are as follows.

[0110] Table 3 shows the strain distribution of points P1 to P12 on a TC17 compressor integral bladed disk forging above and below the phase transformation point:

[0111]

[0112]

[0113] To verify the rationality of the process, the process parameters were used to forge the integral bladed disk of the TC17 titanium alloy compressor, and microstructure observation and performance testing were performed. The microstructure of the integral bladed disk is as follows: Figure 8 As shown in Table 4, the mechanical properties of the overall bladed disk are as follows.

[0114] Table 4 shows the test results of the mechanical properties of a certain TC17 compressor integral bladed disk forging:

[0115]

Claims

1. A method for determining the process parameters for forging a TC17 titanium alloy integral bladed disk across β, characterized in that, The specific process is as follows: Step 1: Develop optimization objectives for the β-forging of the TC17 titanium alloy integral bladed disk: The optimization objective of the finite element numerical simulation is that the equivalent strain of each part of the axial section of the integral bladed disk forging is in the range of 0.6 to 1.7, the equivalent strain above the phase transformation point is in the range of 0.4 to 1.2, and the equivalent strain below the phase transformation point is in the range of 0.2 to 0.

5. Step 2: Draw the mold and blank drawings for the TC17 titanium alloy integral bladed disk: The mold has an axisymmetric structure, and during the simulation, the equivalent strain and temperature change of any axial section can represent the entire mold; the billet has an axisymmetric structure, and during the simulation, the equivalent strain and temperature change of any axial section can represent the entire bladed disk of the TC17 titanium alloy fan; two-dimensional diagrams of the mold and the billet are drawn respectively. Step 3: Perform finite element numerical simulation of the TC17 titanium alloy integral bladed disk: Finite element numerical simulation of TC17 titanium alloy integral bladed disk was performed, and the equivalent strain distribution diagram of the integral bladed disk and the historical data of equivalent strain and temperature change of each part were exported. Import the simulation files of the mold and the blank into the finite element numerical simulation software in sequence. Set the initial simulation parameters, including mold temperature, billet temperature, and forging speed; Following conventional methods, a shear friction model was adopted with a friction coefficient of 0.3 and a heat transfer coefficient of 5 N / sec / mm / ℃. Finite element numerical simulation of the integral bladed disk of the TC17 titanium alloy fan was performed to obtain and export the equivalent strain distribution diagram of the integral bladed disk and the historical data of equivalent strain and temperature change at points P1 to P13. Step 4: Calculate the strain distribution values ​​of each part above and below the phase transition point: Based on the derived equivalent strain and temperature change history data of each part, the equivalent strain change history data is divided into two parts: strain above the phase transformation point and strain below the phase transformation point, with the phase transformation point of the TC17 titanium alloy as the boundary. Step 5, optimize forging parameters: The forging parameters include die temperature, billet temperature, and forging speed; The equivalent strain of the TC17 titanium alloy integral bladed disk obtained by simulation and the strain of each part above and below the phase transformation point are compared with the optimization target of finite element numerical simulation. If all the equivalent strains are within the range of the optimization target, then the mold temperature, billet temperature and forging speed meet the requirements; if any of the equivalent strains are outside the range of the optimization target, then the mold temperature, billet temperature and forging speed do not meet the requirements, and the mold temperature, billet temperature and forging speed are adjusted to obtain new mold temperature, billet temperature and forging speed. Repeat step 3, and use the new mold temperature, billet temperature and forging speed to perform a new finite element numerical simulation of the TC17 titanium alloy integral bladed disk to obtain the new equivalent strain distribution diagram of the integral bladed disk and the historical data of equivalent strain and temperature change of each part. Repeat step 4 to calculate the new strain distribution values ​​of each part above and below the phase transformation point, and compare the obtained new strain distribution values ​​of each part above and below the phase transformation point with the optimization target respectively, and determine whether the mold temperature, billet temperature and forging speed meet the requirements based on the comparison results. If the comparison results prove that the mold temperature, billet temperature, and forging speed meet the requirements, proceed to the next step; otherwise, continue to adjust the mold temperature, billet temperature, and forging speed, and repeat steps 3 and 4 until the mold temperature, billet temperature, and forging speed meet the requirements. When all the equivalent strains are within the range of the optimization target, the current mold temperature value, billet temperature value and forging speed value are the optimized forging parameters. When adjusting the die temperature, billet temperature, and forging speed The mold temperature is 10–80°C below the phase transformation point of TC17 titanium alloy, with an adjustment step of 5°C each time; the billet temperature is 10–60°C above the phase transformation point of TC17 titanium alloy, with an adjustment step of 5°C each time; the forging speed is ≤5mm / s, and is adjusted in steps of 0.5mm / s.

2. The method for determining the process parameters for forging a TC17 titanium alloy integral bladed disk across β as described in claim 1, characterized in that, The axial section of the integral bladed disk forging is a section passing through the center along the height direction of the integral bladed disk. Since the integral bladed disk is an axisymmetric structure, the equivalent strain distribution on any axial section can represent the equivalent strain distribution of the integral bladed disk.

3. The method for determining the process parameters for forging a TC17 titanium alloy integral bladed disk across β as described in claim 1, characterized in that, The mold temperature is 10–80°C below the phase transformation point of the TC17 titanium alloy; the billet temperature is 10–60°C above the phase transformation point of the TC17 titanium alloy; and the forging speed is less than or equal to 5 mm / s.

4. The method for determining the process parameters for forging a TC17 titanium alloy integral bladed disk across β as described in claim 1, characterized in that, The equivalent strain distribution diagram of the integral bladed disk is a two-dimensional diagram of the equivalent strain on the axial section of the integral bladed disk obtained by finite element numerical simulation; the various parts of the integral bladed disk are the position points of the integral bladed disk disk and blade body, and the position points are selected evenly on the integral bladed disk using conventional methods; the historical data of equivalent strain and temperature change are the data of equivalent strain and temperature change throughout the entire process from the start to the end of forging.

5. The method for determining the process parameters for forging a TC17 titanium alloy integral bladed disk across β as described in claim 1, characterized in that, The strain above the phase transformation point and the strain below the phase transformation point represent the degree of deformation of the TC17 titanium alloy above the phase transformation point and the degree of deformation below the phase transformation point, respectively.

6. The method for determining the process parameters for forging a TC17 titanium alloy integral bladed disk across β as described in claim 1, characterized in that, In optimizing forging parameters, the die temperature, billet temperature, and forging speed can be adjusted using a single variable, or a two- or three-variable adjustment. The adjustment principle is as follows: when the strain above the phase transformation point is greater than the optimization target range, or the strain below the phase transformation point is less than the optimization target range, then the die temperature should be reduced, the billet temperature increased, or the forging speed reduced; when the strain above the phase transformation point is less than the optimization target range, or the strain below the phase transformation point is greater than the optimization target range, then the die temperature should be increased, the billet temperature decreased, or the forging speed increased.

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