Titanium alloy and preparation method thereof maintaining medium-high strength and high toughness in sheet layer, net basket, dual-state and equiaxed structure states

Abstract

The present application belongs to the field of metal material processing, and relates to a titanium alloy with high strength and high toughness in sheet layer, net basket, duplex and equiaxed structure states and a preparation method thereof. The alloy composition is as follows: aluminum 8.06% to 9.41%, molybdenum 1.27% to 1.67%, chromium 2.36% to 3.08%, zirconium 0.31% to 0.72%, silicon 0.18% to 0.32%, oxygen 0.12% to 0.35%, and the balance is a titanium matrix and other inevitable impurity atoms. After vacuum consumable melting, cogging forging and homogenizing forging, the alloy has excellent structure state adaptability, especially in the sheet layer, net basket, duplex and equiaxed structure states of medium and large thickness forgings, the medium-high strength, especially the matching fracture toughness and impact toughness are maintained. The ultimate tensile strength-fracture toughness-impact toughness performance of the sheet layer type forging reaches >=920MPa- >=100MPa·m 1 / 2 - >=60J / cm 2 . The structure state adaptability and strength-toughness matching of the alloy system are more excellent than those of common titanium alloys such as TC4, TA15 and TC21.

Description

Technical Field

[0001] This invention belongs to the field of metal material processing and relates to a titanium alloy that maintains medium-high strength and high toughness under different microstructures and its preparation method. Specifically, it relates to a titanium alloy that maintains medium-high strength and high toughness under lamellar, basket, biaxial and equiaxed microstructures and its preparation method. Background Technology

[0002] Titanium alloys, due to their high specific strength, good corrosion resistance, and fatigue resistance, have become key structural materials in aerospace, marine engineering, and high-end equipment manufacturing. The mechanical properties of titanium alloys are closely related to their chemical composition, hot working process, and microstructure. In engineering applications, different types of microstructures can be obtained by adjusting the chemical composition and hot working process, among which basketweave, lamellar, equiaxed, and bimodal microstructures are the four most representative. For most titanium alloys, the differences in microstructure lead to significant differences in the matching of comprehensive mechanical properties. For example, basketweave typically has high fracture toughness and good creep resistance, but its tensile plasticity and high-cycle fatigue performance are not high. Lamellar microstructures also have excellent fracture toughness, but their plasticity and impact toughness are usually low. Equiaxed microstructures have good tensile plasticity, high strength, and excellent fatigue performance, but their fracture toughness is often the worst. Bimodal microstructures generally combine the advantages of equiaxed and lamellar microstructures, with a good strength-plasticity match and relatively excellent impact toughness, but their fracture toughness is generally not high.

[0003] In fact, the aforementioned diverse microstructures endow titanium alloys with designability, but also present a long-standing technical challenge: the mechanical properties of titanium alloys, especially fracture toughness and impact toughness, which are crucial for safety and reliability, exhibit significant differences under different microstructures and are difficult to balance simultaneously. This directly leads to the development and application of most titanium alloys using a single microstructure type in pursuit of optimal mechanical property matching, restricting the expanded application and design freedom of titanium alloys and hindering their development into a new generation of general-purpose titanium alloys. Even the most widely used Ti-6Al-4V (TC4) alloy, with its lamellar, equiaxed, and bimodal microstructures, has been developed and widely applied in engineering fields, but still suffers from the following prominent problems: the strength and impact toughness of this alloy are generally not high under all four microstructures; the fracture toughness under equiaxed and bimodal microstructures is significantly lower than that under lamellar microstructures; and the overall strength-toughness matching capability of the alloy is low.

[0004] Therefore, there is an urgent need in this field to develop a novel titanium alloy whose core feature is excellent adaptability to different microstructures. That is, under the same chemical composition system, this alloy can exhibit high strength and, in particular, well-matched fracture toughness and impact toughness in basket-like, lamellar, equiaxed, and biaxial microstructures. Such an alloy possesses excellent comprehensive performance and strong versatility, which will greatly broaden the application fields of titanium alloys, improve structural safety and reliability, reduce the difficulty of manufacturing process control, and has significant engineering application value. Summary of the Invention

[0005] The technical problem this invention aims to solve is to address the insufficient overall performance matching ability of existing alloys under different microstructures. This invention provides a titanium alloy and its preparation method that maintains medium-to-high strength and high toughness in lamellar, basket-like, biaxial, and equiaxed microstructures. This achieves excellent microstructure adaptability under the same chemical composition system, particularly exhibiting high strength and well-matched fracture toughness and impact toughness in basket-like, lamellar, equiaxed, and biaxial microstructures.

[0006] The technical solution of this invention is:

[0007] From a materials science perspective, the scientific design of the chemical composition of titanium alloys directly determines their economy, advanced nature, and versatility. In the field of titanium alloys, commonly used alloying elements mainly include: α-stabilizing elements such as aluminum, β-stabilizing elements such as molybdenum, chromium, vanadium, niobium, and iron, and neutral elements such as zirconium and tin. Aluminum, an α-stabilizing element, can both strengthen and stabilize the α phase, manifested as an increase in the alloy's phase transformation point. Aluminum atoms are generally dissolved in the titanium matrix through substitutional solid solution. It is currently accepted that the atomic percentage of aluminum atoms in the titanium matrix should generally not exceed 15%, otherwise brittle intermetallic compounds are easily precipitated. Our research shows that when the atomic percentage of aluminum atoms is 6%–10%, it is possible to simultaneously strengthen the α phase and optimize the distribution behavior of β-stabilizing elements between the α and β phases. Furthermore, within this range, the addition of aluminum atoms did not significantly inhibit dislocation movement and twin formation in the α phase, thus ensuring the alloy's plasticity and toughness. In engineering practice, aluminum equivalent is often used to evaluate the content of α-stabilizing elements in titanium alloys. The primary function of β-stabilizing elements is to stabilize the β phase, thus providing a foundation for subsequent microstructural control, particularly improving the strength-ductility / toughness balance and hardenability of the alloy. Molybdenum and vanadium are both isomorphous β-stabilizing elements; relatively speaking, molybdenum is cheaper and therefore more commonly used in engineering. Molybdenum atoms strengthen the titanium matrix through solid solution, and can also refine the β grains and α phase lamellar thickness, significantly improving the alloy's resistance to deformation. Among eutectoid β-stabilizing elements, chromium and iron are more commonly used. Although iron is inexpensive and has strong β-stability, its tendency to segregate increases the difficulty of smelting, while chromium has a much lower tendency to segregate. Chromium atoms also significantly improve alloy strength through solid solution strengthening and promoting age-induced precipitation strengthening, while also contributing to excellent hardenability, hot workability, and cold formability. In practice, molybdenum equivalent is often used to assess the β-stabilizing element content in titanium alloys. To balance the effects of α and β stabilizing elements, a certain amount of zirconium or tin is usually added. The introduction of these two atoms can refine the β grains and the thickness of the α phase lamellar layer, thereby improving the strength of the alloy. In addition, interstitial oxygen atoms (α stabilizing element) and impurity silicon atoms also have a significant impact on the strength-ductility / toughness balance of titanium alloys. Their content should not be too high, otherwise it will easily reduce ductility and toughness. A certain amount of silicon atoms has a positive effect on improving the high-temperature strength and creep performance of the alloy. Although other studies have recently demonstrated that a high oxygen content (about 1% atomic percentage) is beneficial to improving the strength-ductility / toughness balance, this has not yet been further verified in engineering.

[0008] Accordingly, this invention provides a method for controlling the chemical composition and microstructure of titanium-molybdenum-chromium-zirconium-aluminum-silicon-oxygen alloys, enabling them to possess excellent microstructure adaptability and exhibit high strength, particularly well-matched fracture toughness and impact toughness. Fracture mechanics studies on titanium alloys with different microstructures show that the reason why basketweave and lamellar structures have significantly higher fracture toughness than equiaxed and biaxial structures is that the coarse β grains and α lamellae in the single-phase region significantly hinder crack propagation, thus requiring more energy. However, the coarse β grains significantly reduce the alloy's plasticity and impact toughness; therefore, it is necessary to add elements such as molybdenum, chromium, and zirconium to refine the β grain size and control the β grain and lamellar α phase size to an appropriate level. Furthermore, by utilizing the distribution rules of alloying elements in the α and β phases, retaining a certain amount of more β phase with mobile slip systems in basketweave and lamellar structures can improve the alloy's plasticity and toughness. The reduced fracture toughness of equiaxed and bimodal microstructures is largely due to the excessively small size of the original β grains. Furthermore, the pinning effect of the primary α phase in the microstructure makes it difficult to coarsen the original β grains in practice, and coarsening itself is detrimental to the plasticity and toughness of this type of microstructure. Therefore, precise control of the content of the two key α-stabilizing elements, aluminum (substitutional) and oxygen (interstitial), becomes crucial for balancing the strength and toughness of this type of microstructure.

[0009] On the one hand, a titanium alloy is provided that maintains medium-high strength and high toughness in lamellar, basket, biaxial, and equiaxed microstructures. The alloy's chemical composition contains 8.06%~9.41% aluminum atoms, 1.27%~1.67% molybdenum atoms, 2.36%~3.08% chromium atoms, 0.31%~0.72% zirconium atoms, 0.18%~0.32% silicon atoms, and 0.12%~0.35% oxygen atoms, with the balance being the titanium matrix and other unavoidable impurity atoms (hydrogen, nitrogen, iron, and carbon, etc.).

[0010] The present invention provides an alloy with an aluminum atomic percentage of 8.06% to 9.41%, for example, 8.26%, 8.46%, 8.66%, 8.86%, 9.06%, or 9.26%; a molybdenum atomic percentage of 1.27% to 1.67%, for example, 1.30%, 1.33%, 1.36%, 1.39%, 1.42%, 1.45%, 1.48%, 1.51%, 1.54%, 1.57%, 1.60%, 1.63%, or 1.66%; a chromium atomic percentage of 2.36% to 3.08%, for example, 2.46%, 2.56%, 2.66%, 2.76%, 2.86%, 2.96%, or 3.06%; and a zirconium atomic percentage of 0.31% to 0.72%. For example, the percentage of zirconium atoms can be 0.36%, 0.41%, 0.46%, 0.51%, 0.56%, 0.61%, 0.66%, or 0.71%; the percentage of silicon atoms is 0.18% to 0.32%, for example, the percentage of silicon atoms can be 0.20%, 0.22%, 0.24%, 0.26%, 0.28%, or 0.30%; the percentage of oxygen atoms is 0.12% to 0.35%, for example, the percentage of oxygen atoms can be 0.14%, 0.16%, 0.18%, 0.20%, 0.22%, 0.24%, 0.26%, 0.28%, 0.30%, 0.32%, or 0.34%. It should be understood that the above values ​​in the above alloy chemical composition provided by the present invention include, but are not limited to, the listed values, and any other value points within the range are equally applicable.

[0011] On the other hand, the present invention also provides a method for preparing a titanium alloy that maintains medium-high strength and high toughness in lamellar, basket, biaxial, and equiaxed microstructures. The preparation method includes the following steps: Step 1: Mix the raw materials according to the component ratio, and use a titanium electrode hydraulic mechanism to form block electrodes or integral electrodes. The block electrodes need to be further welded into integral electrodes by methods such as vacuum argon plasma welding box or tungsten inert gas welding. The integral electrodes are then subjected to three vacuum self-consumable melting processes to form alloy ingots. Step 2: Use a forging hydraulic press to forge the alloy ingot into a primary billet, and then use a forging hydraulic press to homogenize the primary billet into an alloy bar or forging billet. Step 3: Further cut the alloy bars or forging billets, and use a forging hydraulic press to forge the bars or forging billets into forgings by free forging or precision die forging. Finally, heat treat the forgings to produce finished forgings.

[0012] Preferably, the alloy composition in step one requires raw materials including industrial-grade sponge titanium (grade 0, 0A, or A), pure aluminum granules (aluminum purity greater than 99.9%, particle size 5 mm to 13 mm), pure zirconium granules (zirconium purity greater than 99.9%, particle size 1 mm to 12 mm), aluminum-molybdenum master alloy particles (molybdenum atomic percentage 20% to 65%, particle size not greater than 0.8 mm), aluminum-chromium master alloy particles (chromium atomic percentage 20% to 70%, particle size 0.2 mm to 5.5 mm), aluminum-silicon master alloy particles (silicon atomic percentage 5% to 25%, particle size 0.8 mm to 30 mm), and titanium dioxide powder (oxygen atomic percentage 30% to 80%, particle size not greater than 0.09 mm).

[0013] When the alloy ingot is forged into a primary billet, the forging temperature is 985℃~1165℃, the forging is 2 to 4 times, and the upsetting deformation per forging is 38%~46%.

[0014] Preferably, when forging the alloy ingot into a primary billet, the forging temperature is 985℃~1165℃, for example, it can be 995℃, 1005℃, 1015℃, 1025℃, 1035℃, 1045℃, 1055℃, 1065℃, 1075℃, 1085℃, 1095℃, 1105℃, 1115℃, 1125℃, 1135℃, 1145℃, or 1155℃. It should be understood that the above values ​​include, but are not limited to, the listed values, and any other value points within the range are also applicable. The number of forging passes is 2 to 4, for example, 2, 3, or 4 passes. The upsetting deformation per pass is 38% to 46%, for example, 39%, 40%, 41%, 42%, 43%, 44%, or 45%. It should be understood that the above values ​​include, but are not limited to, the listed values, and any other value points within the range are also applicable.

[0015] When the primary billet is homogenized and forged into bars or forging blanks, the forging temperature is 825℃~955℃, the forging number of forging passes is 4 to 10, and the upsetting deformation amount per pass is 20%~42%.

[0016] Preferably, when the primary billet is homogenized and forged into bars or forging blanks, the forging temperature is 825℃~955℃, for example, it can be 835℃, 845℃, 855℃, 865℃, 875℃, 885℃, 895℃, 905℃, 915℃, 925℃, 935℃, or 945℃. It should be understood that the above values ​​include, but are not limited to, the listed values, and any other value points within the range are also applicable. The number of forging passes is 4 to 10, for example, it can be 4, 5, 6, 7, 8, 9, or 10 passes. The upsetting deformation per pass is 20%~42%, for example, it can be 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, or 40%. It should be understood that the above values ​​include, but are not limited to, the listed values, and any other value points within the range are also applicable.

[0017] When bar stock or forging billet is made into lamellar structure forgings, the forging temperature is 825℃~895℃, and the heat treatment adopts a quasi-β heat treatment process.

[0018] Preferably, when the bar stock or forging billet is made into a lamellar structure forging, the forging temperature is 825℃~895℃, for example, it can be 830℃, 835℃, 840℃, 845℃, 850℃, 855℃, 860℃, 865℃, 870℃, 875℃, 880℃, 885℃, or 890℃. It should be understood that the above values ​​include, but are not limited to, the listed values, and any other value points within the range are also applicable.

[0019] When forging bars or billets into basket-like structures, the forging temperature is 900℃~945℃, and the heat treatment adopts a double annealing process.

[0020] Preferably, when the bar stock or forging billet is made into a basket-like structure forging, the forging temperature is 900℃~945℃, for example, 905℃, 910℃, 915℃, 920℃, 925℃, 930℃, 935℃, 940℃. It should be understood that the above values ​​include, but are not limited to, the listed values, and any other value points within the range are also applicable.

[0021] When bar stock or billet is made into a bimorphic forging, the forging temperature is 856℃~895℃, and the heat treatment adopts a double annealing process.

[0022] Preferably, when the bar stock or forging billet is made into a forging with a dual-state microstructure, the forging temperature is 856℃~895℃, for example, it can be 861℃, 866℃, 971℃, 976℃, 881℃, 886℃, or 891℃. It should be understood that the above values ​​include, but are not limited to, the listed values, and any other value points within the range are also applicable.

[0023] When bar stock or forging billets are made into equiaxed forgings, the forging temperature is 825℃~855℃, and the heat treatment adopts a double annealing process.

[0024] Preferably, when the bar stock or forging billet is made into an equiaxed structure forging, the forging temperature is 825℃~855℃, for example, it can be 830℃, 835℃, 840℃, 845℃, or 850℃. It should be understood that the above values ​​include, but are not limited to, the listed values, and any other value points within the range are also applicable.

[0025] The numerical ranges described in this invention include not only the specific values ​​listed above, but also any values ​​within the ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not list the specific values ​​included in each range.

[0026] The beneficial effects of this invention are: In this alloy system, the addition of aluminum atoms at a percentage of 8.06% to 9.41% is preferred. This effectively strengthens the α phase through solid solution and avoids the precipitation of brittle α2 phase, thus achieving the goal of toughening the α phase. Furthermore, the oxygen atom percentage is further preferably 0.12% to 0.35%. Within this range, oxygen atoms can strengthen the α phase through interstitial solid solution while maintaining its plasticity. Through the combined effect of aluminum and oxygen atoms, the α phase in different morphologies (e.g., strip-shaped α phase in basketweave and lamellar structures, primary α phase and coarse strip-shaped α phase in equiaxed and bimorphic structures) exhibits a good balance of strength and toughness. In particular, these two elements are effective in plasticizing and toughening. During high-temperature hot deformation, they can induce a large number of slip dislocations and nanotwin deformation within the α phase to improve hot deformation processing capabilities. At room temperature, they can induce a large number of plane slip and cross-slip dislocations within the α phase, effectively dispersing stress concentration and improving toughness and plasticity.

[0027] Furthermore, the preferred atomic percentages of molybdenum, chromium, and zirconium in this alloy system are 1.27%~1.67%, 2.36%~3.08%, and 0.31%~0.72%, respectively. Their main functions are as follows: First, these elements within this range effectively refine the original β grain size. Even with extended heating and holding times during quasi-β heat treatment or quasi-β forging, excessive growth of the original β grains (original β grain size not exceeding 300 micrometers) can be prevented, thereby improving the alloy's toughness and plasticity, especially ensuring its plasticity. Second, these β-stabilizing elements effectively stabilize the β phase. Under the influence of elemental distribution, a portion of the residual β phase is retained at room temperature. These soft phases are dispersed throughout the microstructure, effectively dispersing stress concentration and improving the microstructure's ability to coordinate deformation, thus enhancing the alloy's toughness and plasticity. Finally, these residual β phases can promote the precipitation of dispersed fine strip-shaped α phases during low-temperature annealing (such as the second annealing process in a double annealing process), further improving the strength of the alloy. They can also form a multi-scale α phase with the coarse strip-shaped α phase, which can especially improve the strength and toughness matching ability of the alloy.

[0028] In this alloy system, the percentage of silicon atoms is further optimized to be 0.18%~0.32%, which can promote the precipitation of nanoscale silicides Ti6Si3 and Ti5Si3 in the microstructure, thereby improving the high-temperature strength and creep strength of the alloy.

[0029] Compared to existing technologies, the alloy of this invention exhibits excellent adaptability to microstructure, especially in medium and thick forgings with lamellar, basket-net, biaxial, and equiaxed microstructures, maintaining medium to high strength and particularly good fracture toughness and impact toughness. Specifically, the ultimate tensile strength-fracture toughness-impact toughness of lamellar forgings can reach ≥920MPa-≥100MPa·m. 1 / 2 -≥60J / cm 2 Horizontal. The ultimate tensile strength, fracture toughness, and impact toughness of forgings of different mesh types can reach ≥960MPa-≥90MPa·m. 1 / 2 -≥65J / cm 2 Horizontal. The ultimate tensile strength, fracture toughness, and impact toughness of forgings with equiaxed and bimodal structures can reach ≥960MPa-≥80MPa·m. 1 / 2 -≥70J / cm 2 Horizontal (see example for details).

[0030] The microstructure adaptability and toughness matching of this alloy system are superior to those of commonly used titanium alloys such as TC4, TA15, and TC21. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The features of various aspects of the embodiments of the present invention will now be described in detail. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can also be practiced without these specific details. The following description of the embodiments is merely intended to provide a better understanding of the invention by illustrating examples. The invention is not limited to any specific setups and methods provided below, but covers all improvements, substitutions, etc., to product structures and methods without departing from the spirit of the invention. In the following description, well-known structures and techniques are not shown to avoid unnecessarily obscuring the invention.

[0033] The method flow of the present invention will be described in detail below with reference to embodiments: Example 1: Alloy composition A: Aluminum: 8.10%, Molybdenum: 1.30%, Chromium: 2.40%, Zirconium: 0.32%, Silicon: 0.20%, Oxygen: 0.13%, with the balance being titanium matrix and unavoidable impurity atoms.

[0034] Alloy composition B: Aluminum: 9.40%, Molybdenum: 1.65%, Chromium: 3.05%, Zirconium: 0.70%, Silicon: 0.30%, Oxygen: 0.34%, balance being titanium matrix and unavoidable impurity atoms.

[0035] Alloy composition C: Aluminum: 8.74%, Molybdenum: 1.46%, Chromium: 2.75%, Zirconium: 0.51%, Silicon: 0.25%, Oxygen: 0.24%, balance being titanium matrix and unavoidable impurity atoms.

[0036] Alloy composition D: Aluminum: 8.85%, Molybdenum: 1.52%, Chromium: 2.65%, Zirconium: 0.45%, Silicon: 0.13%, Oxygen: 0.18%, with the balance being titanium matrix and unavoidable impurity atoms. All alloy raw materials were mixed, pressed into electrodes, welded, and subjected to three vacuum arc remelting processes to form ingots. These ingots were then forged in three stages at 1155℃ (45.5% deformation), 1055℃ (42.5% deformation), and 990℃ (42.5% deformation), followed by further forging at 865℃ (35.5% deformation), 935℃ (37.5% deformation), 865℃ (35.5% deformation), 935℃ (37.5% deformation), and 865℃ (35.5% deformation). After being homogenized by forging at 865℃ (35.5% deformation) and 865℃ (30.0% deformation) seven times, the forgings were drawn into bars with a diameter of 300 mm. These bars were then forged at 842℃ (35.5% deformation) to produce free forgings with a thickness of 110 mm. Double annealing and quasi-β heat treatment were then applied to obtain forgings with equiaxed microstructure (primarily examining the changes in fracture toughness within this composition range) and lamellar microstructure (primarily examining the changes in impact toughness within this composition range). Their mechanical properties are shown in Table 1, exhibiting good microstructure adaptability and a good balance of strength and toughness.

[0037] Table 1 Mechanical Properties

[0038] Example 2: Alloy composition E: Aluminum: 8.65%, Molybdenum: 1.50%, Chromium: 2.70%, Zirconium: 0.48%, Silicon: 0.18%, Oxygen: 0.28%, balance being titanium matrix and unavoidable impurity atoms. Alloy raw materials were mixed, pressed into electrodes, welded, and subjected to three vacuum arc remelting processes to form ingots. These ingots were then forged in three passes at 1150℃ (42.5% deformation), 1050℃ (43.0% deformation), and 995℃ (44.0% deformation). Following this, they underwent six homogenization forging passes at 872℃ (33.5% deformation), 940℃ (35.5% deformation), 872℃ (36.0% deformation), 940℃ (35.5% deformation), 872℃ (35.5% deformation), and 872℃ (30.0% deformation), before being drawn into a 200mm thick forging blank. This blank was then forged at 872℃ (38.0% deformation) to form a frame forging with an effective thickness of 150mm. A quasi-β heat treatment was then applied to obtain a lamellar structure frame forging. Its mechanical properties are shown in Table 2, exhibiting good microstructure adaptability and a good balance of strength and toughness.

[0039] Table 2 Mechanical Properties

[0040] Example 3: Alloy composition F: Aluminum: 8.70%, Molybdenum: 1.55%, Chromium: 2.68%, Zirconium: 0.55%, Silicon: 0.23%, Oxygen: 0.16%, balance being titanium matrix and unavoidable impurity atoms. Alloy raw materials are mixed, pressed into electrodes, welded, and subjected to three vacuum consumable melting processes to form ingots. The ingots are then forged in three stages at 1130℃ (45.0% deformation), 1030℃ (44.0% deformation), and 986℃ (43.0% deformation). After homogenization forging in seven stages at 880℃ (35.5% deformation), 950℃ (37.0% deformation), 880℃ (35.5% deformation), 950℃ (37.0% deformation), 880℃ (35.5% deformation), 880℃ (30.0% deformation), and 880℃ (25.0% deformation), they are drawn into bars with a diameter of 400mm. After forging at 925℃ (34.0% deformation), beam forgings with an effective thickness of 90mm are formed. Double annealing heat treatment is then used to obtain beam forgings with a mesh basket structure. Its mechanical properties are shown in Table 3, demonstrating good adaptability to tissue state and a good balance of strength and toughness.

[0041] Table 3 Mechanical Properties

[0042] Example 4: Alloy composition G: Aluminum: 8.68%, Molybdenum: 1.43%, Chromium: 2.78%, Zirconium: 0.49%, Silicon: 0.26%, Oxygen: 0.22%, with the balance being titanium matrix and unavoidable impurity atoms. The alloy raw materials are mixed, pressed into electrodes, welded, and subjected to three vacuum arc remelting processes to form ingots. These ingots are then forged in three stages at 1150℃ (43.0% deformation), 1050℃ (43.0% deformation), and 990℃ (42.0% deformation), followed by further forging at 860℃ (36.5% deformation), 950℃ (35.0% deformation), 860℃ (36.5% deformation), 950℃ (35.0% deformation), and 860℃ (36.5% deformation). After being homogenized by forging at 860℃ (30.0% deformation), 860℃ (25.0% deformation), 860℃ (20.0% deformation), 860℃ (20.0% deformation), and 860℃ (20.0% deformation) for 10 heats, the forged bar was drawn to a diameter of 200mm. This bar was then forged again at 860℃ (35.0% deformation) to produce a long beam forging with an effective thickness of 125mm. A double annealing heat treatment was then applied to obtain a long beam forging with a dual-phase microstructure. Its mechanical properties are shown in Table 4, exhibiting good microstructure adaptability and a good balance of strength and toughness.

[0043] Table 4 Mechanical Properties

[0044] Example 5: The alloy composition is as follows: Aluminum: 8.80%, Molybdenum: 1.38%, Chromium: 2.58%, Zirconium: 0.55%, Silicon: 0.28%, Oxygen: 0.30%, with the balance being titanium matrix and unavoidable impurity atoms. The alloy raw materials are mixed, pressed into electrodes, welded, and subjected to three vacuum arc remelting processes to form ingots. These ingots are then forged in three stages at 1130℃ (45.0% deformation), 1030℃ (42.0% deformation), and 988℃ (42.0% deformation), followed by further forging at 878℃ ​​(38.5% deformation), 955℃ (32.0% deformation), 878℃ ​​(38.5% deformation), and 955℃ (33.0% deformation). After being homogenized by forging at 800℃ (0% deformation), 878℃ ​​(38.5% deformation), 878℃ ​​(38.0% deformation), 878℃ ​​(22.0% deformation), and 878℃ ​​(20.0% deformation) eight times, the forgings were drawn into bars with a diameter of 300mm. These bars were then forged at 880℃ (36.0% deformation) to produce joint forgings with an effective thickness of 125mm. Quasi-β heat treatment was then applied to obtain lamellar structure joint forgings. Their mechanical properties are shown in Table 5, exhibiting good microstructure adaptability and a good balance of strength and toughness.

[0045] Table 5 Mechanical Properties

[0046] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A titanium alloy that maintains medium-high strength and high toughness in lamellar, basket-like, biaxial, and equiaxed microstructures, characterized in that, The titanium alloy contains 8.06% to 9.41% aluminum atoms, 1.27% to 1.67% molybdenum atoms, 2.36% to 3.08% chromium atoms, 0.31% to 0.72% zirconium atoms, 0.18% to 0.32% silicon atoms, and 0.12% to 0.35% oxygen atoms, with the balance being the titanium matrix and other unavoidable impurity atoms.

2. A method for preparing the titanium alloy as described in claim 1, characterized in that, The method includes the following steps: Step 1: Mix the raw materials according to the component ratio and make them into segmented electrodes or integral electrodes. The segmented electrodes are further welded to form integral electrodes. The integral electrodes are then subjected to three vacuum self-consumption melting processes to form alloy ingots. Step 2: The alloy ingot is forged into a primary billet, and then the primary billet is further homogenized by forging to produce alloy bars or forging blanks. Step 3: Further cut the alloy bar or forging billet into blanks, and then perform free forging or precision die forging to produce forgings. Finally, perform heat treatment on the forgings to produce finished forgings.

3. The method as described in claim 2, characterized in that, Step 1: Raw materials include: Industrial-grade titanium sponge, pure aluminum granules, pure zirconium granules. Aluminum-molybdenum master alloy particles: molybdenum atomic percentage is 20%~65%. Aluminum-chromium master alloy particles: chromium atomic percentage is 20%~70%. Aluminum-silicon master alloy particles: silicon atomic percentage is 5%~25%. and Titanium dioxide powder: oxygen atom percentage is 30%~80%.

4. The method as described in claim 2, characterized in that, In step two, when the alloy ingot is forged into a primary billet, the forging temperature is 985℃~1165℃, the forging is 2 to 4 times, and the upsetting deformation per forging is 38%~46%.

5. The method as described in claim 2, characterized in that, Step 2 involves homogenizing the primary billet and forging it into bars or forging blanks. The forging temperature is 825℃~955℃, and the forging process is 4 to 10 times. The upsetting deformation per forging is 20%~42%.

6. The method as described in claim 2, characterized in that, Step 3: When forming lamellar structure forgings from bars or billets, the forging temperature is 825℃~895℃, and the heat treatment adopts a quasi-β heat treatment process.

7. The method as described in claim 2, characterized in that, Step 3: When forming the bar stock or forging billet into a basket-like structure forging, the forging temperature is 900℃~945℃, and the heat treatment adopts a double annealing process.

8. The method as described in claim 2, characterized in that, Step 3: When forming a bimetallic forging from bar stock or billet, the forging temperature is 856℃~895℃, and the heat treatment adopts a double annealing process.

9. The method as described in claim 2, characterized in that, Step 3: When forming equiaxed forgings from bars or billets, the forging temperature is 825℃~855℃, and the heat treatment adopts a double annealing process.

10. The method as described in claim 3, characterized in that, The aluminum particles have a purity greater than 99.9% and a particle size of 5 mm to 13 mm. Zirconium particles have a purity greater than 99.9% and a particle size of 1 mm to 12 mm. The particle size of the aluminum-molybdenum master alloy is no greater than 0.8 mm. The particle size of the aluminum-chromium master alloy is 0.2 mm to 5.5 mm. The particle size of the aluminum-silicon master alloy is 0.8 mm to 30 mm. Titanium dioxide powder with a particle size of no more than 0.09 mm.

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