Preparation method of high-toughness Ti80 titanium alloy forge piece for low-temperature ocean engineering

Abstract

The invention discloses a preparation method of a high-toughness Ti80 titanium alloy forge piece for low-temperature ocean engineering, and relates to a preparation method of a titanium alloy forge piece. The invention aims to solve the problem that the obdurability of the existing titanium alloy is not matched. According to the method, through high-temperature large-deformation forging machining and reduction of the forging heating number, the two-phase region annealing treatment process is combined, structure uniformity and high-strength-high-toughness matching at the low temperature are achieved, the titanium alloy forge piece obtains good obdurability matching at the low temperature, and the titanium alloy forge piece has excellent strength and good toughness at the same time; a new manufacturing method is provided for development of titanium alloy forgings with matched strength and toughness for ocean engineering, and the usability of Ti80 titanium alloy materials is greatly expanded. And the forging period and cost are remarkably reduced, the process controllability is enhanced, and the requirements of the high-toughness titanium alloy forge piece for ocean engineering are met.

Description

Technical Field

[0001] This invention relates to a method for preparing titanium alloy forgings. Background Technology

[0002] The deep sea is a strategic resource treasure trove for human development, encompassing fields such as marine engineering, marine resources, and the marine environment. Deep-sea submersibles place higher demands on the strength and toughness of materials. In the deep-sea environment, metallic materials generally face a series of problems, including a sharp decrease in toughness, an increase in the brittle transition temperature, and a shift in fracture mode from ductility to brittleness. This often leads to sudden and unpredictable catastrophic failures of structural components during service. Therefore, developing and selecting materials with excellent low-temperature toughness and stable mechanical response is a fundamental prerequisite and core technological requirement for key areas such as deep-sea engineering, polar exploration, cryogenic propulsion systems, and aerospace cryogenic energy storage equipment. In cryogenic environments, metallic materials are often prone to brittleness, leading to catastrophic accidents. Therefore, to prevent material failure at low temperatures, selecting materials with excellent low-temperature toughness has become an important prerequisite for cryogenic load-bearing applications. Large-size near-α titanium alloy forgings are widely used in deep-sea pressure-resistant structures, aerospace load-bearing components, and high-reliability equipment. Their service performance directly affects the safety and structural integrity of equipment in extreme environments.

[0003] During the strengthening process of titanium alloys, a mismatch between strength and toughness often exists, where one increases at the expense of the other. As strength increases, internal slippage in titanium alloys becomes restricted, and defect sensitivity increases, easily leading to localized stress concentration and microcrack propagation, resulting in a significant decrease in toughness. Conversely, pursuing high toughness requires weakening the strengthening mechanism and improving deformation coordination, often sacrificing strength—a "strength-toughness mismatch." This contradiction is particularly pronounced at low temperatures for structural materials like titanium alloys, where a single strengthening method cannot simultaneously achieve high strength and high toughness, limiting their service reliability under extreme conditions. Therefore, how to control the microstructure through forging processes, break the inverse relationship between strength and toughness, and achieve a synergistic improvement in strength and toughness is a key research direction in current material modification and engineering applications. Summary of the Invention

[0004] This invention addresses the problem of mismatch between strength and toughness in existing titanium alloys by proposing a method for preparing high-strength and high-toughness Ti80 titanium alloy forgings for low-temperature marine engineering.

[0005] The preparation method of the high-strength and high-toughness Ti80 titanium alloy forging for cryogenic marine engineering of the present invention is carried out according to the following steps:

[0006] 1. Homogenize the forged raw materials of Ti80 titanium alloy by heat treatment;

[0007] The homogenization heat treatment temperature is 1100-1200℃, and the holding time is 40min-12h.

[0008] 2. Remove the oxide layer from the surface of the raw material after the homogenization heat treatment in step 1, and then upset drawing and forging to obtain the billet;

[0009] The upsetting and drawing forging process is as follows: the raw material is heated to the forging temperature and held for 40 minutes, and then upsetting and drawing forging is performed. The height reduction during upsetting and drawing forging is 60%; the forging temperature is 900-980℃.

[0010] Third, the billet obtained in step two is subjected to tempering treatment;

[0011] The tempering treatment is performed at a temperature of 900-980℃ for 20 minutes.

[0012] IV. The forging billet obtained in step three is formed and forged to obtain a titanium alloy forging;

[0013] The forming forging process is as follows: forming forging is performed below the phase transformation point, the forging temperature is 900-980℃, the holding time is t=0.4H (in minutes), where H is the height of the forging billet, and t is in mm; the deformation amount during forging is 30%.

[0014] 5. The titanium alloy forgings obtained in step 4 are subjected to α+β two-phase annealing heat treatment.

[0015] The annealing heat treatment process for the α+β two-phase region is as follows: the heat treatment temperature is 30-50℃ below the phase transformation point, and the holding time is 1-2 hours.

[0016] The mechanical properties of near-alpha titanium alloys are generally closely related to the grain size, morphology, and distribution of the alpha phase. In the forging process of traditional titanium alloys, to simultaneously ensure the matching of comprehensive mechanical properties such as strength and toughness at low temperatures, a "high-temperature-low-temperature" or "high-temperature-low-temperature-high-temperature" process route is typically adopted. This involves first subjecting the titanium alloy ingot to multiple upsetting and drawing forging processes above the phase transformation point to break down and refine the as-cast grains. Regardless of whether "high-temperature-low-temperature" or "high-temperature-low-temperature-high-temperature" is used, the billet is heated to the two-phase region for multiple upsetting and drawing forging processes before finishing to break down and refine the alpha phase, thereby improving the alloy's plasticity.

[0017] Unlike the traditional forging processes for titanium alloys mentioned above, this application, specifically targeting the characteristics of Ti80 titanium alloy, studies the hot deformation behavior and microstructure evolution of Ti80 titanium alloy through preliminary hot compression experiments. The hot compression experiments used φ8×12mm compression specimens prepared from forged and annealed Ti80 alloy plates. Single-pass isothermal compression tests were conducted on a Gleeble-3500 thermal simulator. The specific process for the single-pass isothermal compression test was as follows: heating to 800-1000°C at a rate of 10°C / s and holding for 300s, then decreasing the temperature by 0.001–1 s... -1 The strain rate was compressed to 60% of the deformation, and water quenching was performed to preserve the high-temperature microstructure, in order to analyze the rheological curves and microstructure characteristics under different process parameters. Hot compression experiments were conducted to explore the correlation between the mechanical properties of Ti80 titanium alloy and the size and morphology of the α-grain. It was found that the optimal processing range for Ti80 titanium alloy is the high-temperature, low-strain region. Subsequent hot working at a temperature range of 900-980℃ (α+β phase region) still ensured that the material maintained good strength-plasticity-toughness matching at low temperatures. Further research revealed that during tempering of the deformed Ti80 titanium alloy, grain growth did not occur when the tempering holding time was t=0.4H. Based on the above research conclusions, this invention explores a complete process for preparing the α+β phase region of high-strength and high-toughness Ti80 titanium alloy forgings for low-temperature marine engineering: First, the Ti80 titanium alloy forging is heat-treated at 1100℃-1200℃ for 40min-12h to homogenize the initial microstructure and improve the hot working plasticity of the alloy; then, the oxide layer on the metal surface of the homogenized heat-treated forging billet is removed, and it is heated to a forging temperature of 900-980℃ for 40min. A one-upsetting and one-drawing deformation process is used, with strict control of the deformation amount in each pass to 60%, to achieve rapid initial refinement and homogenization of the microstructure; subsequently, the deformed billet is tempered, and the forging billet after multiple heat treatments of the Ti80 alloy is further forged below the phase transformation point, with the forging temperature controlled at 900-980℃ to ensure a deformation amount of 30%. The resulting titanium alloy forging is then obtained. Finally, the obtained Ti80 modified titanium alloy was subjected to (α+β) two-phase annealing heat treatment at a temperature 30-50°C below the phase transformation point, with a holding time of 1-2 hours, followed by air cooling. The initial microstructure of the forged raw material of Ti80 titanium alloy consisted of equiaxed α phase and thick lamellar α phase precipitated in a β phase matrix, with α phase accounting for 90-97% and β phase accounting for 3-10%, and the average grain size of α phase being 20-30 μm. After treatment according to this invention, the average grain size of α phase in the Ti80 titanium alloy was 0.1-10 μm, and the proportion of β phase increased; a two-phase microstructure consisting of equiaxed α phase and fine lamellar α phase was obtained, with α phase accounting for 40-50% and β phase accounting for 50-60%; or a Widmanstätten microstructure consisting of fine lamellar α phase was obtained, with α phase accounting for 20-30% and β phase accounting for 70-80%.

[0018] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0019] 1. This invention uses α+β forging to obtain Ti80 titanium alloy materials. It eliminates the need for high-temperature large deformation above the β phase transformation point to initially break up the cast crystals. At the same time, it strictly controls the heating temperature and deformation amount in the two-phase region. The cold material only needs one tempering to complete the finished forging billet. Compared with the traditional process of forging billets into finished products in the two-phase region, it has the advantages of fewer forging times and shorter forging cycle, which greatly reduces the forging cost of Ti80 titanium alloy materials.

[0020] 2. This invention utilizes high-temperature, large-deformation forging and reduces the number of forging passes, combined with a two-phase annealing process. The deformation process of Ti80 titanium alloy occurs entirely within the α+β phase region. Each heating and forging process is accompanied by recrystallization, dynamic recovery, and softening behaviors such as phase transformation. The deformed microstructure largely disappears during repeated recrystallization, achieving uniform microstructure and a high strength-high toughness balance at low temperatures. This results in titanium alloy forgings with excellent strength and toughness at low temperatures, providing a new manufacturing method for developing high-strength, high-toughness titanium alloy forgings for marine engineering, greatly expanding the applicability of Ti80 titanium alloy materials. Furthermore, the forging cycle and cost are significantly reduced, and process controllability is enhanced, meeting the demand for high-strength, high-toughness titanium alloy forgings for marine engineering. Attached Figure Description

[0021] Figure 1 Metallographic image of the annealed Ti80 titanium alloy prepared in Example 1;

[0022] Figure 2 SEM image of the annealed microstructure of Ti80 titanium alloy prepared in Example 1;

[0023] Figure 3 Metallographic image of the annealed Ti80 titanium alloy prepared in Example 2;

[0024] Figure 4 SEM image of the annealed microstructure of Ti80 titanium alloy prepared in Example 2. Detailed Implementation

[0025] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any reasonable combination of the specific embodiments.

[0026] Specific Implementation Method 1: The preparation method of the high-strength and high-toughness Ti80 titanium alloy forgings for low-temperature marine engineering in this implementation method is carried out according to the following steps:

[0027] 1. Homogenize the forged raw materials of Ti80 titanium alloy by heat treatment;

[0028] The homogenization heat treatment temperature is 1100-1200℃, and the holding time is 40min-12h.

[0029] 2. Remove the oxide layer from the surface of the raw material after the homogenization heat treatment in step 1, and then upset drawing and forging to obtain the billet;

[0030] The upsetting and drawing forging process is as follows: the raw material is heated to the forging temperature and held for 40 minutes, and then upsetting and drawing forging is performed. The height reduction during upsetting and drawing forging is 60%; the forging temperature is 900-980℃.

[0031] Third, the billet obtained in step two is subjected to tempering treatment;

[0032] The tempering treatment is performed at a temperature of 900-980℃ for 20 minutes.

[0033] IV. The forging billet obtained in step three is formed and forged to obtain a titanium alloy forging;

[0034] The forming forging process is as follows: forming forging is performed below the phase transformation point, the forging temperature is 900-980℃, the holding time is t=0.4H (in minutes), where H is the height of the forging billet, and t is in mm; the deformation amount during forging is 30%.

[0035] 5. The titanium alloy forgings obtained in step 4 are subjected to α+β two-phase annealing heat treatment.

[0036] The annealing heat treatment process for the α+β two-phase region is as follows: the heat treatment temperature is 30-50℃ below the phase transformation point, and the holding time is 1-2 hours.

[0037] This embodiment has the following beneficial effects:

[0038] 1. This embodiment uses α+β forging to obtain Ti80 titanium alloy materials. It does not require high-temperature large deformation above the β phase transformation point to initially break up the cast crystals. At the same time, it strictly controls the heating temperature and deformation amount in the two-phase region. The cold material only needs one tempering to complete the finished forging billet. Compared with the traditional process of forging billets into finished products in the two-phase region, it has the advantages of fewer forging times and shorter forging cycle, which greatly reduces the forging cost of Ti80 titanium alloy materials.

[0039] 2. This embodiment utilizes high-temperature, large-deformation forging and reduces the number of forging passes, combined with a two-phase annealing process. The deformation process of the Ti80 titanium alloy occurs entirely within the α+β phase region. Each heating and forging process is accompanied by recrystallization, dynamic recovery, and softening behaviors such as phase transformation. The deformed microstructure largely disappears during repeated recrystallization, achieving uniform microstructure and a high strength-high toughness balance at low temperatures. This results in titanium alloy forgings with excellent strength and toughness at low temperatures, providing a new manufacturing method for developing high-strength, high-toughness titanium alloy forgings for marine engineering, greatly expanding the applicability of Ti80 titanium alloy materials. Furthermore, the forging cycle and cost are significantly reduced, and process controllability is enhanced, meeting the demand for high-strength, high-toughness titanium alloy forgings for marine engineering.

[0040] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the Ti80 titanium alloy described in step one contains 5.42-5.6 wt.% Al, 2.69-3.83 wt.% Nb, 1.91-2.04 wt.% Zr, and 1.35-1.48 wt.% Mo, with Ti as the balance. The yield strength, tensile strength, and elongation of this titanium alloy at low temperatures are all improved compared to those at room temperature.

[0041] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method Two in that: the Ti80 titanium alloy described in step one contains 5.40 wt.% Al, 2.71 wt.% Nb, 1.91 wt.% Zr, and 1.34 wt.% Mo, with Ti as the balance; the phase transformation temperature T... β =1030℃.

[0042] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method Two in that: the Ti80 titanium alloy described in step one contains 5.60 wt.% Al, 2.83 wt.% Nb, 2.04 wt.% Zr, and 1.41 wt.% Mo, with Ti as the balance; the phase transformation temperature T... β =1032℃.

[0043] Specific Implementation Method 5: This implementation method differs from one of the specific implementation methods one to four in that the homogenization heat treatment in step one is performed at a temperature of 1100°C for 40 minutes.

[0044] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the upsetting and drawing forging process described in step two is as follows: the raw material is heated to 980°C and held for 40 minutes, and then upsetting and drawing forging is performed, with the height reduction of upsetting and drawing forging being 60%.

[0045] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the tempering temperature in step three is 980°C and the time is 20 minutes.

[0046] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: the forming and forging process described in step four is as follows: the forging temperature is 980℃, the holding time is t=0.4H, where H is the height of the forging billet, H is 80mm, and the unit of t is min; the deformation amount of forging is 30%.

[0047] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the cooling method for the α+β two-phase region annealing heat treatment described in step five is air cooling.

[0048] Specific Implementation Method 10: This implementation method differs from Specific Implementation Methods 1 to 9 in that the α+β two-phase region annealing heat treatment process described in step 5 is as follows: the heat treatment temperature is 980℃ and the holding time is 1.5 hours.

[0049] Example 1:

[0050] The preparation method of the high-strength and high-toughness Ti80 titanium alloy forging for cryogenic marine engineering in this embodiment is carried out according to the following steps:

[0051] 1. Homogenize the forged raw materials of Ti80 titanium alloy by heat treatment;

[0052] The homogenization heat treatment temperature is 1100℃, and the holding time is 40min;

[0053] The Ti80 titanium alloy contains 5.40 wt.% Al, 2.71 wt.% Nb, 1.91 wt.% Zr, and 1.34 wt.% Mo, with Ti as the balance; the phase transformation temperature T... β =1030℃;

[0054] 2. Remove the oxide layer from the surface of the raw material after the homogenization heat treatment in step 1, and then upset drawing and forging to obtain the billet;

[0055] The upsetting and drawing forging process is as follows: the raw material is heated to 980°C and held for 40 minutes, and then upsetting and drawing forging is performed. The height reduction during upsetting and drawing forging is 60%.

[0056] Third, the billet obtained in step two is subjected to tempering treatment;

[0057] The tempering treatment was performed at a temperature of 980°C for 20 minutes.

[0058] IV. The forging billet obtained in step three is formed and forged to obtain a titanium alloy forging;

[0059] The forming forging process is as follows: forming forging is performed below the phase transformation point, the forging temperature is 980℃, the holding time is t=0.4H, where H is the height of the forging billet, H is 80mm, and t is in min; the deformation amount of forging is 30%;

[0060] 5. The titanium alloy forgings obtained in step 4 are subjected to α+β two-phase annealing heat treatment.

[0061] The annealing heat treatment process for the α+β two-phase region is as follows: the heat treatment temperature is 980℃, the holding time is 1.5 hours, and the cooling method is air cooling.

[0062] The initial microstructure of the forged Ti80 titanium alloy raw material was composed of equiaxed α phase and thick lamellar α phase precipitated in a β phase matrix, with α phase accounting for 96.6% and β phase accounting for 3.3%. After treatment in this embodiment, the microstructure is a bimodal microstructure composed of equiaxed α phase and fine lamellar α phase, with α phase accounting for 45.44% and β phase accounting for 54.56%; the average grain size of the α phase is 7.75 μm (statistical analysis using Image Pro Plus software). Figure 1 The image shows the metallographic structure of the Ti80 titanium alloy prepared in the annealed state in Example 1. It can be seen that the microstructure of the material consists of uniform grains with no obvious flow lines or metallurgical defects. Figure 2 The corresponding SEM images show that the microstructure is very uniform. Table 1 shows the mechanical properties of the material obtained in Example 1, which demonstrates that the Ti80 titanium alloy prepared in Example 1 exhibits excellent comprehensive performance at both low temperature (-100℃) and room temperature (25℃).

[0063] Table 1

[0064]

[0065] Example 2:

[0066] The preparation method of the high-strength and high-toughness Ti80 titanium alloy forging for cryogenic marine engineering in this embodiment is carried out according to the following steps:

[0067] 1. Homogenize the forged raw materials of Ti80 titanium alloy by heat treatment;

[0068] The homogenization heat treatment temperature is 1100℃, and the holding time is 40min;

[0069] The Ti80 titanium alloy contains 5.60 wt.% Al, 2.83 wt.% Nb, 2.04 wt.% Zr, and 1.41 wt.% Mo, with Ti as the balance; the phase transformation temperature T... β =1032℃;

[0070] 2. Remove the oxide layer from the surface of the raw material after the homogenization heat treatment in step 1, and then upset drawing and forging to obtain the billet;

[0071] The upsetting and drawing forging process is as follows: the raw material is heated to 980°C and held for 40 minutes, and then upsetting and drawing forging is performed. The height reduction during upsetting and drawing forging is 60%.

[0072] Third, the billet obtained in step two is subjected to tempering treatment;

[0073] The tempering treatment was performed at a temperature of 980°C for 20 minutes.

[0074] IV. The forging billet obtained in step three is formed and forged to obtain a titanium alloy forging;

[0075] The forming forging process is as follows: forming forging is performed below the phase transformation point, the forging temperature is 980℃, the holding time is t=0.4H, where H is the height of the forging billet, H is 80mm, and t is in min; the deformation amount of forging is 30%;

[0076] 5. The titanium alloy forgings obtained in step 4 are subjected to α+β two-phase annealing heat treatment; the process of α+β two-phase annealing heat treatment is as follows: the heat treatment temperature is 990℃, the holding time is 1 hour, and the cooling method is air cooling.

[0077] The initial microstructure of the forged raw material of Ti80 titanium alloy is composed of equiaxed α phase and thick lamellar α phase precipitated in a β phase matrix, with α phase accounting for 96.6% and β phase accounting for 3.3%. After treatment in this embodiment, the microstructure is Widmanstätten structure composed of fine lamellar α phase, with α phase accounting for 27.36% and β phase accounting for 72.64%, and the average grain size of α phase is 0.59 μm.

[0078] Figure 3 Metallographic image of the annealed Ti80 titanium alloy prepared in Example 2; Figure 4 SEM image of the annealed microstructure of Ti80 titanium alloy prepared in Example 2. Figure 3 It can be seen that the material structure consists of uniform grains with no obvious flow lines or metallurgical defects; Figure 4 It can be seen that the structure is very uniform. Table 2 shows the mechanical properties of the material obtained in Example 2. It can be seen that the Ti80 titanium alloy prepared in Example 1 has excellent comprehensive performance at low temperature (-100℃) and room temperature (25℃).

[0079] Table 2

[0080]

[0081] The above test results show that the Ti80 titanium alloy material prepared by the method of the present invention has excellent low-temperature performance. Compared with the room temperature performance, the yield strength (YS) and tensile strength (UTS) are improved, and the elongation (ε) is also improved.

Claims

1. A method for preparing high-strength and high-toughness Ti80 titanium alloy forgings for low-temperature marine engineering, characterized in that: The preparation method of high-strength and high-toughness Ti80 titanium alloy forgings for cryogenic marine engineering is carried out according to the following steps:

1. Homogenize the forged raw materials of Ti80 titanium alloy by heat treatment; The homogenization heat treatment temperature is 1100-1200℃, and the holding time is 40min-12h.

2. Remove the oxide layer from the surface of the raw material after the homogenization heat treatment in step 1, and then upset drawing and forging to obtain the billet; The upsetting and drawing forging process is as follows: the raw material is heated to the forging temperature and held for 40 minutes, and then upsetting and drawing forging is performed. The height reduction during upsetting and drawing forging is 60%; the forging temperature is 900-980℃. Third, the billet obtained in step two is subjected to tempering treatment; The tempering treatment is performed at a temperature of 900-980℃ for 20 minutes. IV. The forging billet obtained in step three is formed and forged to obtain a titanium alloy forging; The forming and forging process is as follows: the forging temperature is 900-980℃, the holding time is t=0.4H (in minutes), where H is the height of the forging billet, and t is in mm; the forging deformation is 30%.

5. The titanium alloy forgings obtained in step 4 are subjected to α+β two-phase annealing heat treatment. The annealing heat treatment process for the α+β two-phase region is as follows: the heat treatment temperature is 30-50℃ below the phase transformation point, and the holding time is 1-2 hours.

2. The method for preparing high-strength and high-toughness Ti80 titanium alloy forgings for low-temperature marine engineering according to claim 1, characterized in that: The Ti80 titanium alloy described in step one contains 5.42-5.6 wt.% Al, 2.69-3.83 wt.% Nb, 1.91-2.04 wt.% Zr, and 1.35-1.48 wt.% Mo, with Ti as the balance.

3. The method for preparing high-strength and high-toughness Ti80 titanium alloy forgings for low-temperature marine engineering according to claim 2, characterized in that: The Ti80 titanium alloy described in step one contains 5.40 wt.% Al, 2.71 wt.% Nb, 1.91 wt.% Zr, and 1.34 wt.% Mo, with Ti as the balance; the phase transformation temperature T... β =1030℃.

4. The method for preparing high-strength and high-toughness Ti80 titanium alloy forgings for low-temperature marine engineering according to claim 2, characterized in that: The Ti80 titanium alloy described in step one contains 5.60 wt.% Al, 2.83 wt.% Nb, 2.04 wt.% Zr, and 1.41 wt.% Mo, with Ti as the balance; the phase transformation temperature T... β =1032℃.

5. The method for preparing high-strength and high-toughness Ti80 titanium alloy forgings for low-temperature marine engineering according to claim 1, characterized in that: The homogenization heat treatment in step one is performed at a temperature of 1100℃ for a holding time of 40 minutes.

6. The method for preparing high-strength and high-toughness Ti80 titanium alloy forgings for low-temperature marine engineering according to claim 1, characterized in that: The upsetting and drawing forging process described in step two is as follows: the raw material is heated to 980°C and held for 40 minutes, and then upsetting and drawing forging is performed. The height reduction during upsetting and drawing forging is 60%.

7. The method for preparing high-strength and high-toughness Ti80 titanium alloy forgings for low-temperature marine engineering according to claim 1, characterized in that: The tempering process described in step three is performed at a temperature of 980℃ for 20 minutes.

8. The method for preparing high-strength and high-toughness Ti80 titanium alloy forgings for low-temperature marine engineering according to claim 1, characterized in that: The forming and forging process described in step four is as follows: the forging temperature is 980℃, the holding time is t=0.4H, where H is the height of the forging billet, H is 80mm, and t is in min; the deformation amount of forging is 30%.

9. The method for preparing high-strength and high-toughness Ti80 titanium alloy forgings for low-temperature marine engineering according to claim 1, characterized in that: The cooling method for the α+β two-phase annealing heat treatment described in step five is air cooling.

10. The method for preparing high-strength and high-toughness Ti80 titanium alloy forgings for low-temperature marine engineering according to claim 1, characterized in that: The annealing heat treatment process for the α+β two-phase region described in step five is as follows: the heat treatment temperature is 980℃ and the holding time is 1.5 hours.

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