Wide-width homogeneous high-toughness TC4ELI titanium alloy forge piece and high-precision preparation method thereof

Abstract

The invention belongs to the technical field of titanium and titanium alloy processing, and relates to a high-precision preparation method of a wide-width homogeneous high-toughness TC4ELI titanium alloy forge piece. The method comprises the following steps: selecting a finished product cast ingot prepared by at least three times of VAR smelting, forging the finished product cast ingot for 8-10 heating numbers to prepare a forging stock D, then carrying out double heat treatment on the forging stock D to obtain a TC4ELI titanium alloy finished product forging, and finally, carrying out performance and flaw detection to obtain the TC4ELI titanium alloy finished product forging meeting the standard. According to the method, a uniform and compact three-dimensional streamline is formed through reversing upsetting, equiaxalization is sufficient, anisotropy is small, advanced free forging technologies such as FM forging and blocking tongue forging are applied, on one hand, initiation of surface cracks can be actively restrained, on the other hand, metal can be more sufficiently deformed in the length direction of a forged piece, the fiber flow direction is optimized, and meanwhile the mechanical performance of the forged piece is improved. And a traditional plate tongue cutting procedure is omitted, so that the material utilization rate is greatly improved, the production period is shortened, and the comprehensive cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of titanium and titanium alloy processing technology, and relates to a high-precision preparation method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings. Background Technology

[0002] TC4ELI titanium alloy, as a typical low-interstitial (specifically referring to the content of interstitial elements such as O, N, and H being controlled at a low level) α+β two-phase titanium alloy, has become an ideal material for key load-bearing structures in aerospace, pressure shells for deep-sea equipment, bogies for high-speed rail transit, and high-end medical implants due to its excellent specific strength, fracture toughness, corrosion resistance, and good biocompatibility.

[0003] With the development of high-end equipment towards larger size, lighter weight, and higher reliability, higher requirements are placed on the specifications and performance of TC4ELI titanium alloy forgings, necessitating the development of wide-width forgings with large projected area and great thickness. However, the preparation of such forgings faces severe technical challenges: extremely difficult forming, wide-width forgings are prone to macroscopic defects such as incomplete filling, contour collapse, and surface tearing during free forging; complex microstructure and property control, traditional free forging processes struggle to simultaneously obtain uniform, fine equiaxed or bimodal microstructures throughout the entire wide cross-section, especially in the core region, and there is a risk of coarse grains and fine bright bands in the core; narrow process window, the alloy is extremely sensitive to forging temperature, and the narrow (α+β) phase region forging window makes temperature fluctuations prone to microstructure loss, leading to significant dispersion in plasticity, toughness, and fatigue properties; increased cracking tendency, the complex internal stress state of wide-width forgings during deformation places extremely high demands on the quality of the original billet and the setting of forging process parameters, otherwise internal or surface cracking is likely to occur.

[0004] Currently, conventional free forging or rolling techniques struggle to overcome the limitations of wide-width dimensions while ensuring high uniformity, high toughness, and stable medium strength in forgings. Therefore, there is an urgent need to develop a novel high-precision method for preparing wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings. This method should systematically address the aforementioned challenges and ultimately achieve the stable preparation of high-toughness, uniformly structured wide-width TC4ELI titanium alloy forgings. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-precision preparation method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings.

[0006] To achieve the above objectives, the present invention provides the following technical solution: On the one hand, the present invention provides a high-precision preparation method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings. The method involves selecting a finished ingot with a specification of Φ760~Φ975mm obtained by at least three VAR melting processes, then forging the finished ingot 8~10 times to obtain a forging blank D, and then subjecting the forging blank D to double heat treatment to obtain a TC4ELI titanium alloy finished forging. Finally, after performance and flaw detection, a TC4ELI titanium alloy finished forging conforming to the standard is obtained.

[0007] Specifically, the high-precision preparation method includes the following steps: Step 1: Select finished ingots with a specification of Φ760~Φ975mm obtained by at least three VAR melting processes; Step 2: The finished ingot is forged 8 to 10 times to obtain the forging billet D; Step 3: Perform double heat treatment on the forging billet D: the first high-temperature annealing temperature is T. β - (30~50)℃, hold for 1~3h; the second low-temperature annealing temperature is 700~800℃, hold for 1~3h, to obtain TC4ELI titanium alloy finished forgings; Step 4: Perform performance and flaw detection tests on the TC4ELI titanium alloy finished forgings to complete the high-precision preparation of the target wide-width, homogeneous, and high-toughness TC4ELI titanium alloy forgings.

[0008] Further, in step 1, an alloy mixture is obtained by using 0A-grade sponge titanium, aluminum briquettes, aluminum-vanadium 65 alloy, titanium-iron alloy, and titanium dioxide according to the component ratio design; the alloy mixture is pressed into electrodes and smelted three times to obtain a finished ingot. The alloy mixture comprises the following elements by weight percentage: aluminum (Al): 6.1%~6.45%, vanadium (V): 4.0%~4.3%, iron (Fe): 0.16%~0.20%, carbon (C) ≤0.08%, nitrogen (N) ≤0.03%, oxygen (O): 0.09%~0.12%, hydrogen (H) ≤0.0125%, and titanium (Ti) as the balance.

[0009] Furthermore, in step 2, the 8-10 forging cycles include, One-time forging: The finished ingot is heated to T β Forging is carried out at +(100~200)℃, and the total deformation is 84%~86%; the forging includes two upsetting and two drawing operations, wherein the ratio of the height to the diameter of the finished ingot during upsetting is 1.5~2.5; the initial forging temperature is ≥900℃, the final forging temperature is >850℃, the forging is air-cooled, and the surface defects are polished to obtain forging billet A; Intermediate forging: includes one high-temperature forging and five to seven low-temperature forgings; The high-temperature forging at Tβ The forging process is carried out in a temperature range of +(50~100)℃, and the total deformation is 80%~90%, resulting in forging billet B. The low-temperature forging at T β The low-temperature forging is carried out in a temperature range of -(30~50)℃, and the holding time is 360~480min. The low-temperature forging includes sequential reversing upsetting forging, FM forging method, and tongue-blocking forging technology forging, and the forging billet C is obtained after forging. First-pass forging of finished product: The forging billet C obtained after intermediate forging is then subjected to T... β The forging process involves drawing and stretching at 30-50℃, with a total deformation of 30%-32%, followed by straightening to obtain the forging billet D.

[0010] More specifically, the forging process specifically includes: The finished ingot is first preheated in a temperature range of 750~850℃ for 90~150 min, and then heated to T for 90~210 min. β +(100~200)℃, heat preservation time is 180~300min; then two upsetting and two drawing forging are carried out to obtain forging billet A.

[0011] More specifically, the high-temperature forging of the intermediate forging process specifically refers to: The forged billet A obtained from the initial forging is preheated in the temperature range of 750~850℃ for 90~150min, and then heated to T in the range of 90~210min. β +(50~100)℃, heat preservation time is 180~300min; then two upsetting and two drawing are carried out, the initial forging temperature is ≥900℃, and the final forging temperature is >850℃; after forging, air cooling and surface grinding are performed to obtain forging billet B.

[0012] More specifically, the low-temperature forging of the intermediate forging process specifically refers to: The forging billet B is preheated in the temperature range of 750℃ to 850℃ for 90 to 120 minutes, and then heated to T in 90 to 210 minutes. β -(30~50)℃, heat preservation time is 360~480min; The fourth and fifth forging processes employ reverse upsetting to achieve the superposition of multi-directional plastic deformation. Through the cycle of "upsetting and compaction → drawing and refining → reversing and repeating," the inherent defects of the casting structure are broken, allowing the metal to form a uniform, dense, and fine recrystallized structure and a reasonable flow line distribution. The final drawing in low-temperature forging yields a square forging billet C, with an initial forging temperature ≥800℃ and a final forging temperature >750℃. The surface is then polished after forging. When reheating in the furnace, the heating temperature is the same as the original temperature, and the holding time is 30~90 minutes.

[0013] More specifically, the finished product forging process involves heating the square forging billet C obtained from the intermediate forging to a temperature T. β -(30~50)℃, holding time is 210~300min, followed by elongation process, initial forging temperature ≥800℃, final forging temperature >750℃, straightening after forging to obtain forging billet D.

[0014] Furthermore, in step 3, the forging blank D is subjected to double annealing, and then straightened to control the plate difference ≤ 5mm and the curvature ≤ 3mm / m, thus obtaining the TC4ELI titanium alloy finished forging.

[0015] Further, in step 4, the TC4ELI titanium alloy finished forgings are subjected to performance and flaw detection tests. Specifically, the performance tests are performed according to the AMS4931C standard, and ultrasonic testing is conducted according to the AA grade in GB / T 5193.

[0016] On the other hand, the present invention also provides a wide-width homogeneous high-toughness TC4ELI titanium alloy forging prepared by some or all of the preparation methods described above, with a thickness of 130~210mm, a width of 1700~2200mm, and a length of 1600~3000mm. The tongue of the TC4ELI titanium alloy forging was reduced from 65mm to 18mm, the forging yield was increased from 90.3% to 94.2%, the intangible loss was reduced from 9.8% to 6.7%, and the forging edges were free from collapse and missing material. The relevant mechanical properties are as follows: longitudinal overall yield strength R p0.2 >810MPa, tensile strength R m >875MPa, elongation after fracture A 4D >13%, reduction of area Z >30%; Transverse overall yield strength R p0.2 >800MPa, tensile strength R m >875MPa, elongation after fracture A 4D >13%, reduction of area Z >30%, fracture toughness K IC >77MPa·m 1 / 2 .

[0017] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: 1) This invention innovatively uses 0A-grade ultra-high purity sponge titanium as the main raw material to improve the purity of the matrix. Pure grain boundaries can effectively inhibit the propagation of cracks along the grain boundaries, which is the key to improving toughness. The TC4ELI alloy ingot prepared by this process has a fundamentally improved elemental purity and microstructure uniformity, laying the foundation for obtaining stable and excellent comprehensive mechanical properties in subsequent forging.

[0018] 2) This invention innovatively proposes a free forging integrated process involving 8-10 heat passes. Compared with processes such as rolling, it has irreplaceable advantages in solving the unique challenges of wide-width forgings, specifically as follows: Through the carefully designed reversing upsetting process in intermediate forging, a uniform and dense three-dimensional streamline network is formed inside the billet, which not only completely breaks the original as-cast structure, but also greatly weakens the anisotropy. This enables the final forging to exhibit highly consistent and excellent mechanical properties in both the longitudinal and transverse directions, especially ensuring the uniformity of the core and surface structure of the thick cross section, effectively overcoming the problem of "size effect". The innovative application of advanced free forging technologies such as "FM forging" and "tongue-blocking forging" can, on the one hand, actively suppress the initiation of surface cracks; on the other hand, it enables the alloy to undergo more complete deformation in the length direction of the forging. While optimizing the fiber flow direction, it eliminates the traditional tongue-cutting process, thereby significantly improving material utilization, shortening the production cycle, and reducing overall costs.

[0019] 3) This invention employs dual heat treatment to achieve precise customization and stabilization of the properties of wide-width TC4ELI alloy forgings: The first high-temperature annealing aims to adjust and stabilize the macrostructure, release processing stress, and promote the full decomposition of the β-transformation structure, creating microstructural conditions for improving plasticity and toughness. The second relatively low-temperature annealing precipitates dispersed and fine secondary α-phase in the metastable β-phase, achieving a significant precipitation strengthening effect. Thus, without losing almost all the good plasticity and toughness brought by the primary α-phase, the yield strength and tensile strength of the material are greatly improved, achieving the best balance between strength and plasticity and toughness. Attached Figure Description

[0020] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1A flowchart of a high-precision preparation method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings provided by this invention; Figure 2(a) is a microstructure of the left side of the 175×2145×1650mm TC4ELI alloy wide forging prepared in Example 1 of the present invention in the width direction; Figure 2(b) is a microstructure of the 175×2145×1650mm TC4ELI alloy wide forging prepared in Example 1 of the present invention, with the microstructure at the center of the width direction. Figure 2(c) is a microstructure of the right side of the 175×2145×1650mm TC4ELI alloy wide forging prepared in Example 1 of the present invention in the width direction. Figure 3(a) is a microstructure of the left side of the 155×1785×2290mm TC4ELI alloy wide forging prepared in Example 2 of the present invention in the width direction; Figure 3(b) is a microstructure of the 155×1785×2290mm TC4ELI alloy wide forging prepared in Example 2 of the present invention, with the microstructure at the center of the width direction. Figure 3(c) is a microstructure of the right side of the 155×1785×2290mm TC4ELI alloy wide forging prepared in Example 2 of the present invention in the width direction; Figure 4(a) is a microstructure of the left side of the 195×1820×2830mm TC4ELI alloy wide forging prepared in Example 3 of the present invention in the width direction; Figure 4(b) is a microstructure of the 195×1820×2830mm TC4ELI alloy wide forging prepared in Example 3 of the present invention, with the microstructure at the center of the width direction. Figure 4(c) is a microstructure of the right side of the 195×1820×2830mm TC4ELI alloy wide forging prepared in Example 3 of the present invention in the width direction. Detailed Implementation

[0023] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0024] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] Example 1 This embodiment provides a high-precision manufacturing method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings. The forging has dimensions of 175×2145×1650mm (thickness × width × length), and the method includes the following steps: Step 1: Select a finished ingot with dimensions of Φ862×1740mm obtained through at least three VAR melting processes, specifically including: The required components of the TC4ELI alloy were mixed and pressed into electrodes according to the required mass ratio. The electrodes were then smelted three times in a VAR melting furnace to obtain a TC4ELI alloy ingot with dimensions of Φ862×1740mm. The TC4ELI alloy composition uses the following mass percentages: 6.41% Al, 4.17% V, 0.184% Fe, 0.098% O, and the balance Ti and other unavoidable impurity elements.

[0026] Step 2: Perform nine forging processes on the TC4ELI alloy ingot, which are divided into initial forging, intermediate forging, and final forging: First forging: The TC4ELI alloy ingot is preheated at 810℃ and held for 120 minutes. Then, the ingot is heated to 1080℃ within 150 minutes and held for 240 minutes. Then, two upsetting and two drawing forging are performed. The ratio of ingot height to diameter during upsetting is 1.92. The total deformation of this forging is 84%. The initial forging temperature is not lower than 900℃ and the final forging temperature is higher than 850℃. After forging, the ingot is air-cooled and surface defects are polished to obtain forging billet A1. Intermediate forging: including one-stage high-temperature forging and six-stage low-temperature forging; The second high-temperature forging process involves preheating billet A1 at 810℃ for 120 minutes, then heating it to 1040℃ within 150 minutes for 240 minutes. This is followed by two upsetting and two drawing forging processes, with a total deformation of 84%. The initial forging temperature is no lower than 900℃, and the final forging temperature is higher than 850℃. After forging, the billet is air-cooled and surface defects are removed to obtain billet B1.

[0027] The third to sixth low-temperature forging: the forging billet B1 is preheated at 810℃ and held for 120 minutes, then heated to 920℃ within 120 minutes and held for 420 minutes; the fourth and fifth forgings are reverse upsetting and drawing, with two upsettings and two drawings per forging, and the total deformation per forging is 80%~85%, with the initial forging temperature not lower than 800℃ and the final forging temperature higher than 750℃; After each upsetting and drawing operation, the forging billet is reheated in the furnace. Its core function is to eliminate work hardening, restore metal plasticity, compensate for heat loss, prevent deformation and cracking, ensure uniform deformation and dimensional accuracy of the forging, promote recrystallization to refine grains, improve microstructure and properties, and facilitate the implementation of large deformation processes. During reheating, the heating temperature is the same as the original temperature, and the holding time is 90 minutes. After forging, the billet is air-cooled, and surface defects are polished.

[0028] The seventh low-temperature forging: The alloy forging billet obtained from the sixth forging is preheated at 810℃ for 120 minutes, then heated to 920℃ within 120 minutes and held for 420 minutes. After heating, the billet undergoes two upsetting and two drawing processes: the second drawing process stretches the billet to 450×2200×L mm. The total deformation in this forging process is 82%, with an initial forging temperature not lower than 800℃ and a final forging temperature higher than 750℃. After one upsetting and one drawing, the billet is reheated in the furnace at the original temperature for 90 minutes. After forging, it is air-cooled and surface defects are polished.

[0029] The eighth low-temperature forging: The alloy forging billet obtained in the seventh forging is heated to 920℃ and held for 300 minutes. After heating, the billet is drawn in one pass to 250×2200×L mm. The total deformation in this forging pass is 42%. The initial forging temperature is not lower than 800℃, and the final forging temperature is higher than 750℃. When reheating in the furnace, the heating temperature is the same as the original temperature, and the holding time is 90 minutes. After forging, the billet is air-cooled and 100% polished to facilitate better forming in the next forging pass and reduce slab defects, resulting in forging billet C1.

[0030] Ninth forging pass: The forging billet C1 is heated to 920℃ and held for 240 minutes. After heating, it is drawn in one pass to a size of 175×2145×1650mm. The total deformation in this forging pass is 32%. The initial forging temperature is not lower than 800℃, and the final forging temperature is higher than 750℃. During reheating, the temperature is the same as the original temperature, and the holding time is 60 minutes. After forging, the residual heat is used for straightening to obtain the forging billet D1.

[0031] Step 3: Perform double heat treatment on the forging billet D1: The first high-temperature annealing heats the alloy forging billet to 910℃ and holds it for 2 hours; the second high-temperature annealing heats the alloy forging billet to 720℃ and holds it for 2 hours. After heat treatment, straighten the billet to obtain the TC4ELI titanium alloy finished forging 1.

[0032] Step 4: Perform performance and flaw detection tests on TC4ELI titanium alloy finished forging 1. The performance tests are performed according to AMS4931C standard, testing the tensile strength in the L and T directions of the forging. R m ), yield strength ( R p0.2 ), elongation ( A 4D ), reduction of area ( Z ), fracture toughness ( K IC Metallographic microstructure, the specific results are shown in Table 1, and the microstructure is shown in Figures 2(a) to 2(c).

[0033] Table 1 Mechanical properties of 175×2145×1650mm forgings As shown in Figures 2(a) to 2(c), the TC4ELI titanium alloy forging 1 prepared in Example 1 is composed of equiaxed primary α phase and β transformation microstructure. The light-colored equiaxed / short rod-shaped grains in the figures represent the primary α phase, which is uniformly distributed and small in size. The dark-colored areas represent the β transformation microstructure (composed of lamellar α phase formed during the cooling of the high-temperature β phase and a small amount of residual β phase), which is distributed discontinuously in a network or lamellar pattern at the grain boundaries and within the grains of the primary α phase. Furthermore, Figures 2(a) to 2(c) show good microstructure uniformity, with no obvious coarse grains, inclusions, or defects. The forging was ultrasonically tested according to the AA grade requirements of GB / T 5193, and the test results met the standard requirements.

[0034] Furthermore, based on the data in Table 1, it can be seen that the wide-width TC4ELI alloy forging 1 prepared in Example 1 achieved a longitudinal overall yield strength. R p0.2 >820MPa, tensile strength R m >880MPa, elongation after fracture A 4D >14%, reduction of area Z >30%; Transverse overall yield strength R p0.2 >815MPa, tensile strength R m >880MPa, elongation after fracture A 4D >15%, reduction of area Z >30%, fracture toughness K IC >93MPa·m 1 / 2 .

[0035] Example 2 This embodiment provides a high-precision manufacturing method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings. The forging has dimensions of 155×1785×2290mm (thickness × width × length). The method includes the following steps: Step 1: Select a finished ingot with dimensions of Φ770×1972mm obtained through at least three VAR melting processes, specifically including: The required components of the TC4ELI alloy were mixed according to the specified mass ratio and pressed into electrodes. These electrodes were then smelted three times in a VAR melting furnace to obtain a TC4ELI alloy ingot with dimensions of Φ770×1972mm. The TC4ELI alloy composition uses the following mass percentages: 6.37% Al, 4.12% V, 0.177% Fe, 0.106% O, and the balance Ti and other unavoidable impurity elements.

[0036] Step 2: Perform eight forging processes on the TC4ELI alloy ingot, which are divided into initial forging, intermediate forging, and final forging: First forging: The TC4ELI alloy finished ingot is preheated at 780℃ and held for 90 minutes. Then, the finished ingot is heated to 1100℃ within 120 minutes and held for 210 minutes. Then, two upsetting and two drawing forging are performed. The ratio of ingot height to diameter during upsetting is 1.8. The total deformation of this forging is 86%. The initial forging temperature is not lower than 900℃ and the final forging temperature is higher than 850℃. After forging, it is air-cooled and surface defects are polished to obtain forging billet A2. Intermediate forging: including one-stage high-temperature forging and five-stage low-temperature forging; The second high-temperature forging process involves preheating the billet A2 at 780°C for 90 minutes, then heating it to 1020°C within 120 minutes for 210 minutes. This is followed by two upsetting and two drawing forging processes. The total deformation in this forging process is 81%, with an initial forging temperature of not less than 900°C and a final forging temperature higher than 850°C. After forging, the billet is air-cooled and surface defects are removed to obtain forging B2.

[0037] The third to fifth low-temperature forging: the forging billet B2 is preheated at 780℃ and held for 90 minutes, then heated to 930℃ within 90 minutes and held for 390 minutes; the fourth and fifth forgings are reversed upsetting and drawing, with two upsettings and two drawings per forging, and the total deformation per forging is 80%, with the initial forging temperature not lower than 800℃ and the final forging temperature higher than 750℃; After each upsetting and drawing operation during intermediate forging, the forged billet is reheated in the furnace. Its core function is to eliminate work hardening, restore metal plasticity, compensate for heat loss, prevent deformation and cracking, ensure uniform deformation and dimensional accuracy of the forging, promote recrystallization to refine grains, improve microstructure and properties, and facilitate the implementation of large deformation processes. During reheating, the heating temperature is the original temperature, and the holding time is 90 minutes. After forging, the billet is air-cooled, and surface defects are polished.

[0038] The sixth low-temperature forging: The alloy forging billet obtained from the fifth forging is preheated at 780℃ for 90 minutes, then heated to 930℃ for 390 minutes. After heating, the billet undergoes two upsetting and two drawing processes: the second drawing process pulls the billet to 330×1900×L mm. The total deformation in this forging process is 80%, with an initial forging temperature not lower than 800℃ and a final forging temperature higher than 750℃. After one upsetting and one drawing, the billet is reheated at the original temperature for 90 minutes. After forging, it is air-cooled and surface defects are polished.

[0039] The seventh low-temperature forging: The alloy forging billet obtained from the sixth forging is heated to 930℃ and held for 240 minutes. After heating, the billet is drawn in one pass to 330×1900×L mm. The total deformation of this forging pass is 40%. The initial forging temperature is not lower than 800℃, and the final forging temperature is higher than 750℃. When reheating in the furnace, the heating temperature is the original temperature, and the holding time is 90 minutes. After forging, the billet is air-cooled and 100% polished to obtain forging billet C2.

[0040] The eighth forging pass: The C2 alloy forging billet is heated to 930℃ and held for 210 minutes. After heating, the billet is drawn in one pass to a size of 155×1785×2290mm. The total deformation in this forging pass is 30%. The initial forging temperature is not lower than 800℃, and the final forging temperature is higher than 750℃. During reheating, the temperature is the same as the original temperature, and the holding time is 60 minutes. After forging, the residual heat is used for straightening to obtain the D2 forging billet.

[0041] Step 3: Perform double heat treatment on the forging billet D2: The first high-temperature annealing heats the alloy forging billet to 920℃ and holds it for 1.5h; the second high-temperature annealing heats the alloy forging billet to 740℃ and holds it for 2.5h. After heat treatment, straighten the billet to obtain the TC4ELI titanium alloy finished forging 2.

[0042] Step 4: Perform performance and flaw detection tests on the TC4ELI titanium alloy finished forging 2. The performance tests are performed according to AMS4931C standard, testing the tensile strength in the L and T directions of the wide forging. R m ), yield strength ( R p0.2 ), elongation ( A 4D ), reduction of area ( Z ), fracture toughness ( K IC Metallographic microstructure, the specific results are shown in Table 2, and the microstructure is shown in Figures 3(a) to 3(c). Table 2 Mechanical properties of 155×1785×2290mm forgings As shown in Figures 3(a) to 3(c), the TC4ELI titanium alloy forging 2 prepared in Example 2 is composed of equiaxed primary α phase and β transformation structure. The light-colored equiaxed / short rod-shaped grains in the figures represent the primary α phase, which is uniformly distributed and small in size. The dark-colored areas represent the β transformation structure (composed of lamellar α phase formed during the cooling of the high-temperature β phase and a small amount of residual β phase), which is distributed discontinuously in a network or lamellar pattern at the grain boundaries and within the grains of the primary α phase. Furthermore, Figures 3(a) to 3(c) show good structural uniformity with no obvious coarse grains, inclusions, or defects. The forging was ultrasonically tested according to the AA grade requirements of GB / T 5193, and the test results met the standard requirements.

[0043] Furthermore, based on the data in Table 2, it can be seen that the TC4ELI alloy forging 2 prepared in Example 2 achieved a longitudinal overall yield strength. R p0.2 >810MPa, tensile strength R m >875MPa, elongation after fracture A 4D >13%, reduction of area Z >30%; Transverse overall yield strength R p0.2 >800MPa, tensile strength R m >875MPa, elongation after fracture A 4D >13%, reduction of area Z >30%, fracture toughness K IC >93MPa·m 1 / 2 .

[0044] Example 3 This embodiment provides a high-precision manufacturing method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings. The forging has dimensions of 195×1820×2830mm (thickness × width × length). The method includes the following steps: Step 1: Select a finished ingot with dimensions of Φ975×1920mm obtained through at least three VAR melting processes, specifically including: The required components of the TC4ELI alloy were mixed according to the specified mass ratio and pressed into electrodes. These electrodes were then smelted three times in a VAR melting furnace to obtain a TC4ELI alloy ingot with dimensions of Φ975×1920mm. The TC4ELI alloy composition uses the following mass percentages: 6.37% Al, 4.29% V, 0.180% Fe, 0.119% O, and the balance Ti and other unavoidable impurity elements.

[0045] Step 2: Perform ten forging cycles on the TC4ELI alloy ingot, which includes initial forging, intermediate forging, and final forging. First forging: The finished ingot is preheated at 850℃ for 150 minutes, then heated to 1150℃ within 210 minutes and held for 270 minutes; then it undergoes two upsetting and two drawing forging, with the ratio of ingot height to diameter being 2.23 during the upsetting; the total deformation of this forging is 85%, the initial forging temperature is not lower than 900℃, the final forging temperature is higher than 850℃, and it is air-cooled after forging, and surface defects are polished to obtain forging billet A3; Intermediate forging: including one-stage high-temperature forging and five-stage low-temperature forging; The second high-temperature forging process involves preheating billet A3 at 850°C for 150 minutes, then heating it to 1080°C within 210 minutes for 270 minutes. This is followed by two upsetting and two drawing forging processes. The total deformation in this forging process is 87%, with an initial forging temperature of no less than 900°C and a final forging temperature above 850°C. After forging, the billet is air-cooled and surface defects are removed to obtain billet B3.

[0046] The third to seventh low-temperature forging: the forging billet B3 is preheated at 850℃ and held for 150 minutes, then heated to 950℃ within 150 minutes and held for 450 minutes; the fourth and fifth forgings are reversed upsetting and drawing, with two upsettings and two drawings per forging, and the total deformation per forging is 83%, with the initial forging temperature not lower than 800℃ and the final forging temperature higher than 750℃; After each upsetting and drawing operation, the forging billet is reheated in the furnace. Its core function is to eliminate work hardening, restore metal plasticity, compensate for heat loss, prevent deformation and cracking, ensure uniform deformation and dimensional accuracy of the forging, promote recrystallization to refine grains, improve microstructure and properties, and facilitate the implementation of large deformation processes. During reheating, the heating temperature is the same as the original temperature, and the holding time is 90 minutes. After forging, the billet is air-cooled, and surface defects are polished.

[0047] The eighth low-temperature forging: The alloy forging billet obtained from the seventh forging is preheated at 850℃ for 150 minutes, then heated to 950℃ within 210 minutes and held for 450 minutes. After heating, the billet undergoes two upsetting and two drawing processes: the second drawing process stretches the billet to 450×1900×L mm. The total deformation in this forging process is 84%, with an initial forging temperature not lower than 800℃ and a final forging temperature higher than 750℃. After one upsetting and one drawing, the billet is reheated in the furnace at the original temperature for 90 minutes. After forging, it is air-cooled and surface defects are polished.

[0048] Ninth low-temperature forging: The alloy forging billet obtained from the eighth forging is heated to 950℃ and held for 360 minutes; after the forging billet is heated, it is drawn in one forging to 280×1900×Lmm. The total deformation of this forging is 42%, the initial forging temperature is not lower than 800℃, and the final forging temperature is higher than 750℃; after forging, it is air-cooled and the surface is 100% polished to obtain forging billet C3.

[0049] The tenth forging pass: The forging billet C3 is heated to 950℃ and held for 270 minutes. After heating, it is drawn in one pass to a size of 195×1820×2830mm. The total deformation in this forging pass is 31%. The initial forging temperature is not lower than 800℃, and the final forging temperature is higher than 750℃. During reheating, the temperature is the same as the original temperature, and the holding time is 60 minutes. After forging, the residual heat is used for straightening to obtain the forging billet D3.

[0050] Step 3: Perform double heat treatment on the forging billet D3: The first high-temperature annealing heats the alloy forging billet to 940℃ and holds it for 2 hours; the second high-temperature annealing heats the alloy forging billet to 770℃ and holds it for 1 hour. After heat treatment, straighten the billet to obtain the TC4ELI titanium alloy finished forging 3.

[0051] Step 4: Perform performance and flaw detection tests on the TC4ELI titanium alloy finished forging 3. The performance tests are performed according to AMS4931C standard, testing the tensile strength in the L and T directions of the wide forging. R m ), yield strength ( R p0.2 ), elongation ( A 4D ), reduction of area ( Z ), fracture toughness ( K IC The results and metallographic microstructure are shown in Table 3 and Figures 4(a) to 4(c).

[0052] Table 3 Mechanical properties of 195×1820×2830mm forgings As shown in Figures 4(a) to 4(c), the TC4ELI titanium alloy forging 3 of Example 3 is composed of equiaxed primary α phase and β transformation microstructure. The light-colored equiaxed / short rod-shaped grains in the figures represent the primary α phase, which is uniformly distributed and small in size. The dark-colored areas represent the β transformation microstructure (composed of lamellar α phase formed during the cooling of the high-temperature β phase and a small amount of residual β phase), which is distributed discontinuously in a network or lamellar pattern at the grain boundaries and within the grains of the primary α phase. Furthermore, Figures 4(a) to 4(c) show good microstructure uniformity with no obvious coarse grains, inclusions, or defects. The forging was ultrasonically tested according to the AA grade requirements of GB / T 5193, and the test results met the standard requirements.

[0053] As shown in Table 3, the TC4ELI alloy forging 3 prepared in Example 3 achieved a longitudinal overall yield strength. R p0.2 >800MPa, tensile strength R m >879MPa, elongation after fracture A 4D >18%, reduction of area Z >36%; Transverse overall yield strength R p0.2 >804MPa, tensile strength R m >880MPa, elongation after fracture A 4D >16%, reduction of area Z >33%, fracture toughness K IC >95MPa·m 1 / 2 .

[0054] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0055] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A high-precision manufacturing method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings, characterized in that, A finished ingot with a specification of Φ760~Φ975mm, obtained by at least three VAR melting processes, is selected. The finished ingot is then forged 8~10 times to obtain a forging blank D. The forging blank D is then subjected to double heat treatment to obtain a TC4ELI titanium alloy finished forging. Finally, the TC4ELI titanium alloy finished forging is subjected to performance and flaw detection tests to obtain a TC4ELI titanium alloy finished forging that meets the standards.

2. The high-precision preparation method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings according to claim 1, characterized in that, Specifically, the following steps are included: Step 1: Select finished ingots with a specification of Φ760~Φ975mm obtained by at least three VAR melting processes; Step 2: The finished ingot is forged 8 to 10 times to obtain the forging billet D; Step 3: Perform double heat treatment on the forging billet D: the first high-temperature annealing temperature is T. β - (30~50)℃, hold for 1~3h; the second low-temperature annealing temperature is 700~800℃, hold for 1~3h, to obtain TC4ELI titanium alloy finished forgings; Step 4: Perform performance and flaw detection tests on the TC4ELI titanium alloy finished forgings to complete the high-precision preparation of the target wide-width, homogeneous, and high-toughness TC4ELI titanium alloy forgings.

3. The high-precision manufacturing method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings according to claim 2, characterized in that, In step 1, an alloy mixture is obtained by using 0A grade sponge titanium, aluminum briquettes, aluminum vanadium 65 alloy, titanium iron alloy, and titanium dioxide according to the component ratio design; the alloy mixture is pressed into electrodes and smelted three times to obtain the finished ingot.

4. The high-precision manufacturing method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings according to claim 2, characterized in that, Step 2, the 8-10 forging cycles includes, One-time forging: The finished ingot is heated to T β Forging is carried out at +(100~200)℃ to obtain forging billet A. The forging includes two upsetting and two drawing operations, wherein the ratio of the height to the diameter of the finished ingot during upsetting is 1.5~2.

5. Intermediate forging: includes one high-temperature forging and five to seven low-temperature forgings; The high-temperature forging at T β The process is carried out in a temperature range of +(50~100)℃, and the holding time is 180~300min; The low-temperature forging at T β The low-temperature forging is carried out in a temperature range of -(30~50)℃, and the holding time is 360~480min. The low-temperature forging includes sequential reversing upsetting forging, FM forging method, and tongue-stopping forging technology forging. First-pass forging of finished product: The billet obtained after intermediate forging is subjected to T-type forging. β The forging billet D is obtained by stretching at -(30~50)℃ and holding for 210~300min.

5. The high-precision manufacturing method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings according to claim 4, characterized in that, The specific process of billet forging is as follows: The finished ingot is first preheated in a temperature range of 750~850℃ for 90~150 min, and then heated to T for 90~210 min. β +(100~200)℃, heat preservation time is 180~300min; then perform two upsetting and two drawing forging to obtain forging billet A.

6. The high-precision manufacturing method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings according to claim 4, characterized in that, The high-temperature forging of the intermediate forging specifically refers to: The forged billet A obtained from the initial forging is preheated in the temperature range of 750~850℃ for 90~150min, and then heated to T in the range of 90~210min. β +(50~100)℃, heat preservation time is 180~300min; then perform two upsetting and two drawing, initial forging temperature ≥900℃, final forging temperature >850℃, grind the surface after forging to obtain forging billet B.

7. The high-precision manufacturing method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings according to claim 6, characterized in that, The low-temperature forging of the intermediate forging specifically refers to: The forging billet B is preheated in the temperature range of 750℃ to 850℃ for 90 to 150 minutes, and then heated to T in 90 to 210 minutes. β -(30~50)℃, heat preservation time is 360~480min; then two upsetting and two drawing are carried out, the initial forging temperature is ≥800℃, the final forging temperature is >750℃, and the surface is polished after forging to obtain forging billet C.

8. The high-precision manufacturing method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings according to claim 7, characterized in that, The forging of the finished product specifically involves: Heat the forged billet C obtained from intermediate forging to T. β -(30~50)℃, heat preservation time is 210~300min, followed by elongation process, initial forging temperature ≥800℃, final forging temperature >750℃, after forging, the forging billet C is straightened to obtain forging billet D.

9. The high-precision manufacturing method for wide-width, homogeneous, high-toughness TC4ELI titanium alloy forgings according to claim 2, characterized in that, In step 3, after double annealing, the forging blank D is straightened to control the plate difference ≤ 5mm and the curvature ≤ 3mm / m, thus obtaining the TC4ELI titanium alloy forging.

10. A wide-width, homogeneous, high-toughness TC4ELI titanium alloy forging prepared by the method described in any one of claims 1 to 9, characterized in that, Longitudinal overall yield strength R p0.2 >810MPa, tensile strength R m >875MPa, elongation after fracture A 4D >13%, reduction of area Z >30%; Transverse overall yield strength R p0.2 >800MPa, tensile strength R m >875MPa, elongation after fracture A 4D >13%, reduction of area Z >30%, fracture toughness K IC >77MPa·m 1 / 2 .

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