Microstructure and performance control method of high-toughness titanium alloy pipe

Abstract

The application discloses a microstructure and performance control method of high-toughness titanium alloy pipe, and relates to the field of titanium alloy pipe production.The method comprises the following steps: firstly, multiple-time multi-directional forging deformation is conducted on a high-toughness titanium alloy ingot to obtain a rod blank with uniform microstructure; secondly, a cross-rolling piercing process is adopted to perform piercing forming and hot rolling on the rod blank at 50-80 DEG C above the beta phase transition point to obtain a rough pipe; thirdly, tension reducing is conducted on the rough pipe after heat preservation at 30-60 DEG C below the beta phase transition point to obtain a pipe blank; and finally, solid solution and aging heat treatment are conducted on the pipe blank to obtain the high-toughness titanium alloy pipe.The synergistic effect of the forging deformation-hot rolling forming-tension reducing can effectively regulate and optimize the size and morphology of the alpha phase in the microstructure, and can refine and homogenize the microstructure, so that the high-toughness titanium alloy pipe with excellent mechanical properties is obtained, and the high-toughness titanium alloy pipe is suitable for fields such as marine engineering.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy technology, specifically relating to a method for controlling the microstructure and properties of high-strength and high-toughness titanium alloy pipes. Background Technology

[0002] Titanium alloys, due to their high specific strength, excellent corrosion resistance, and stability in extreme environments, have become key materials in marine engineering, shipbuilding, and oil exploration. Especially in deep-sea pressure hulls, ship cooling pipes, and offshore oil and gas pipelines, seamless titanium alloy tubes withstand harsh conditions involving high-pressure, highly corrosive media transport and long-term dynamic loads. Their microstructure uniformity and mechanical property stability directly determine the service life and safety of the equipment. However, traditional seamless titanium alloy tubes are prone to problems such as uneven microstructure, residual texture, and performance fluctuations during hot extrusion, skew rolling, and piercing processes, severely restricting their high-end applications in the marine and energy sectors.

[0003] Currently, there are many publicly disclosed high-strength and high-toughness titanium alloy tubes: Patent CN109706344A discloses a cold-rolled titanium alloy tube with a yield strength ≥931MPa, tensile strength ≥1000MPa, elongation ≥13%, and full-size Charpy V-type impact energy ≥41J; Patent CN111593230A discloses an extruded titanium alloy drill rod with a yield strength ≥933MPa, tensile strength ≥1051MPa, elongation ≥10%, and impact energy ≥60J; Patent CN119114672A discloses an extruded titanium alloy tube with a yield strength ≥900MPa, elongation ≥10%, and impact energy ≥50J at -20℃. In actual production, regardless of the tube manufacturing method, there is a problem of poor strength-toughness matching due to unreasonable coordination of temperature and deformation processes. For the microstructure and performance control in the fully automated hot-rolled titanium alloy tube manufacturing process, there is currently no mature control technology due to the greater difficulty in process coordination.

[0004] Patent CN107541615A discloses a high-strength and high-toughness titanium alloy for marine engineering. This alloy possesses excellent strength, toughness, and corrosion resistance, and is a novel titanium alloy for high-strength and high-toughness pipes used in my country's marine engineering and oil exploration fields in recent years. Regarding this alloy, methods for cold rolling and extrusion to prepare titanium alloy pipes have been disclosed in patents CN112605123A and CN119114672A. The process, microstructure, and properties of hot rolling to prepare pipes from this alloy have not yet been disclosed. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for controlling the microstructure and properties of high-strength and high-toughness titanium alloy tubes. This method involves hot rolling and tension reduction processing of billets prepared by multi-stage multi-directional forging to effectively adjust and optimize the size and morphology of the α-phase in the microstructure, and to refine and homogenize the microstructure, thereby obtaining high-strength and high-toughness titanium alloy tubes with excellent mechanical properties. This solves the problem of difficulty in controlling the microstructure and properties during the hot continuous rolling process of high-strength titanium alloys in the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for controlling the microstructure and properties of high-strength and high-toughness titanium alloy pipes, characterized in that the method includes the following steps: Step 1: Perform multi-fire, multi-directional forging deformation on the high-strength and high-toughness titanium alloy ingot, using an upsetting and drawing process with a single deformation amount of 30%~50%, to obtain a high-strength and high-toughness titanium alloy billet with a uniform α+β two-phase structure and an average grain size of no more than 300μm. Step 2: Using the skew rolling piercing process, the high-strength and high-toughness titanium alloy billet obtained in Step 1 is pierced and hot rolled at 50℃~80℃ above the β phase transformation point to obtain a high-strength and high-toughness titanium alloy tube. Step 3: Hold the high-strength and tough titanium alloy tube obtained in Step 2 at 30℃~60℃ below the β phase transformation point for 1h~2h, and then perform tension reduction processing, with a cumulative reduction of 50%~55%, to optimize the microstructure and obtain a high-strength and tough titanium alloy tube blank. Step 4: The high-strength and high-toughness titanium alloy tube blank obtained in Step 3 is subjected to solution treatment and aging heat treatment to obtain a high-strength and high-toughness titanium alloy tube with the target microstructure and excellent mechanical properties.

[0007] The aforementioned method for controlling the microstructure and properties of a high-strength and high-toughness titanium alloy pipe is characterized in that the high-strength and high-toughness titanium alloy mentioned in step one is the high-strength and high-toughness titanium alloy described in patent application number 201710798608.7. The patent application number 201710798608.7 is entitled "A High-Strength and High-Toughness Titanium Alloy for Marine Engineering".

[0008] The aforementioned method for controlling the microstructure and properties of high-strength and high-toughness titanium alloy tubing is characterized by the following step: The high-strength and high-toughness titanium alloy ingot is heated to 40°C~150°C above the β-phase transformation point for a three-stage, three-directional upsetting and drawing forging process, with a single deformation amount of 40%~50%. The resulting forging is then heated to 10°C~20°C below the β-phase transformation point for a two-stage, three-directional upsetting and drawing forging process, with a single deformation amount of 30%~40%. After forging, the forging is water-cooled. The water-cooled forging is then heated to 10°C~20°C below the β-phase transformation point for a single-stage drawing and elongation forging, with a single deformation amount of 30%. After forging, the forging is air-cooled. By controlling the specific process and parameters of the multi-stage, multi-directional forging and deformation, a high-strength and high-toughness titanium alloy billet with an average grain size not exceeding 300μm is obtained, providing a genetic basis for obtaining the target microstructure.

[0009] The aforementioned method for controlling the microstructure and properties of high-strength and high-toughness titanium alloy tubing is characterized in that the deformation amount in step two, namely 60%~70%, during piercing and hot rolling, is 60%~70%. By controlling the degree of deformation during piercing and hot rolling at corresponding temperatures, the grain size and α-phase morphology ratio are directly controlled, thus having a crucial impact on the microstructure and properties of the titanium alloy tubing.

[0010] The aforementioned method for controlling the microstructure and properties of a high-strength and high-toughness titanium alloy tube is characterized in that the optimized microstructure described in step three is as follows: grain size not exceeding 40 μm, with staggered strip-shaped α clusters, the width of the strip-shaped α clusters being 1 μm to 3 μm, and the length not exceeding 20 μm. This optimized microstructure provides the optimal microstructure basis for subsequent heat treatment.

[0011] The aforementioned method for controlling the microstructure and properties of a high-strength and high-toughness titanium alloy pipe is characterized by the following steps: the solution heat treatment in step four is performed by holding at 40℃~60℃ below the β phase transformation point for 1h~2h, followed by air cooling; the aging heat treatment is performed by holding at 500℃~600℃ for 4h, followed by air cooling. By controlling the temperature and holding time of the solution and aging heat treatments, the synergistic optimization of the strength and toughness of the titanium alloy pipe is ensured.

[0012] The aforementioned method for controlling the microstructure and properties of a high-strength and high-toughness titanium alloy tube is characterized by the following: the target microstructure in step four is characterized by equiaxed α-phase grain size controlled at 2μm~8μm, short and thick strip-shaped α-phase width controlled at 1μm~4μm, and uniform distribution of strip-shaped α-phase clusters and equiaxed α-phase clusters. This type of microstructure can effectively coordinate the material's deformation capacity. The short and thick strip-shaped α-phase effectively improves the insufficient impact performance caused by the long and thin strip-shaped α-phase and, to a certain extent, compensates for the insufficient strength of the equiaxed α-phase.

[0013] The microstructure and performance control method of the above-mentioned high-strength and high-toughness titanium alloy pipe is characterized in that the excellent mechanical properties mentioned in step four are: the high-strength and high-toughness titanium alloy pipe has a yield strength of more than 910 MPa, an elongation of more than 16% and an impact energy of more than 50 J.

[0014] Compared with the prior art, the present invention has the following advantages: 1. This invention first uses multi-fire, multi-directional forging deformation to ensure that the prepared billet has sufficient microstructure uniformity and grain refinement effect. Then, it combines skew rolling piercing process, including piercing forming and hot continuous rolling, to adjust the size and morphology of α phase in the microstructure. Then, it optimizes the morphology of grain boundary α phase by using tension reduction process and controlling its cumulative reduction amount, so that the microstructure is refined and uniform. This effectively regulates and controls the microstructure in high-strength and high-toughness titanium alloy tubes, resulting in high-strength and high-toughness titanium alloy tubes with excellent mechanical properties.

[0015] 2. This invention effectively controls the dimensional gradient and morphology of the rolled microstructure by precisely controlling the temperature of piercing forming, hot continuous rolling, and tension reduction processing, providing a controllable deformation thermodynamic basis for obtaining the optimal microstructure after subsequent heat treatment.

[0016] 3. By precisely controlling the deformation amount in piercing forming, hot continuous rolling, and tension reduction processing, this invention achieves optimal deformation distribution in each process, ensuring the forming quality of high-strength and high-toughness titanium alloy tubes while obtaining the maximum grain refinement effect and improving the forming efficiency of high-strength and high-toughness titanium alloy tubes.

[0017] 4. This invention achieves a microstructure with controlled equiaxed α-phase grain size of 2μm~8μm, controlled short and thick strip-shaped α width of 1μm~4μm, and uniform distribution of strip-shaped α clusters and equiaxed α clusters through the synergistic effect of forging deformation, hot rolling forming, and tension reduction. The resulting high-strength and high-toughness titanium alloy tube has a yield strength of over 910MPa, an elongation of over 16%, and an impact energy of over 50J. This achieves a triple improvement in microstructure uniformity, performance stability, and process economy, providing technical support for the industrial application of high-end titanium alloy tubes.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 The image shows the metallographic structure of the high-strength and high-toughness titanium alloy tube prepared in Example 1 of this invention. Detailed Implementation

[0020] Example 1 This embodiment includes the following steps: Step 1: The high-strength and high-toughness titanium alloy ingot is subjected to multi-fire, multi-directional forging deformation using an upsetting and drawing process with a single deformation amount of 40%, to obtain a high-strength and high-toughness titanium alloy billet with a uniform α+β two-phase structure and an average grain size of 280μm. The high-strength and high-toughness titanium alloy ingot is composed of the following components by mass percentage: Al 5.72%, Sn 1.03%, Zr 3.64%, Mo 1.08%, V 1.05%, Nb 3.12%, with the balance being Ti and unavoidable impurities. The multi-fire, multi-directional forging deformation process is as follows: the high-strength and high-toughness titanium alloy ingot is heated to 150°C, 90°C, and 40°C above the β phase transformation point and subjected to three-fire, three-directional upsetting and drawing forging, with a single deformation amount of 40%. Then, the obtained forging is heated to 10°C below the β phase transformation point and subjected to two-fire, three-directional upsetting and drawing forging, with a single deformation amount of 40%. After forging, it is water-cooled. Then, the water-cooled forging is heated to 10°C below the β phase transformation point and subjected to one-fire drawing and lengthening forging, with a single deformation amount of 30%. After forging, it is air-cooled. Step 2: Using a skew rolling piercing process, the high-strength and high-toughness titanium alloy billet obtained in Step 1 is pierced and hot rolled at 50°C above the β phase transformation point to obtain a high-strength and high-toughness titanium alloy tube; the deformation amount of the piercing forming is 60%, and the deformation amount of the hot rolling is 70%. Step 3: The high-strength and tough titanium alloy tube obtained in Step 2 is kept at 60°C below the β phase transformation point for 1 hour, and then subjected to tension reduction processing with a cumulative reduction of 50% to optimize the microstructure and obtain a high-strength and tough titanium alloy tube blank. The optimized microstructure is as follows: grain size 40μm, strip-shaped α clusters are interspersed, strip-shaped α width is 1μm~3μm, and maximum length is 17μm. Step 4: The high-strength and high-toughness titanium alloy tube blank obtained in Step 3 is subjected to solution treatment and aging heat treatment to obtain a high-strength and high-toughness titanium alloy tube with the target microstructure and excellent mechanical properties. The solution heat treatment process is as follows: holding at 60℃ below the β phase transformation point for 1 hour, followed by air cooling; the aging heat treatment process is as follows: holding at 500℃ for 4 hours, followed by air cooling. The target microstructure is as follows: the equiaxed α phase grain size is controlled at 2μm~8μm, the width of the short and coarse strip-shaped α phase is controlled at 1μm~4μm, and the strip-shaped α clusters and equiaxed α clusters are evenly distributed, such as... Figure 1 As shown.

[0021] According to the test results, the high-strength and high-toughness titanium alloy pipe prepared in this embodiment has a yield strength of 915 MPa, an elongation of 17%, and an impact energy of 54.2 J.

[0022] Example 2 This embodiment includes the following steps: Step 1: The high-strength and high-toughness titanium alloy ingot is subjected to multi-fire, multi-directional forging deformation using an upsetting and drawing process with a single deformation amount of 50%, to obtain a high-strength and high-toughness titanium alloy billet with a uniform α+β two-phase microstructure and an average grain size of 250μm; the high-strength and high-toughness titanium alloy ingot is composed of the following composition by mass percentage: Al 5.72%, Sn 1.03%, Zr 3.64%, Mo 1.08%, V 1.05%, Nb 3.12%, with the balance being Ti and unavoidable impurities; The process of multi-fire multi-directional forging deformation is as follows: the high-strength and high-toughness titanium alloy ingot is heated to 150°C, 90°C and 40°C above the β phase transformation point and subjected to three-fire three-directional upsetting and drawing forging, with a single deformation amount of 50%. Then the obtained forging is heated to 10°C below the β phase transformation point and subjected to two-fire three-directional upsetting and drawing forging, with a single deformation amount of 40%. After forging, it is water-cooled. Then the water-cooled forging is heated to 10°C below the β phase transformation point and subjected to one-fire drawing and lengthening forging, with a single deformation amount of 30%. After forging, it is air-cooled. Step 2: Using a skew rolling piercing process, the high-strength and high-toughness titanium alloy billet obtained in Step 1 is pierced and hot rolled at 70°C above the β phase transformation point to obtain a high-strength and high-toughness titanium alloy tube; the deformation amount of the piercing forming is 67%, and the deformation amount of the hot rolling is 64%. Step 3: The high-strength and tough titanium alloy tube obtained in Step 2 is kept at 60°C below the β phase transformation point for 1 hour, and then subjected to tension reduction processing, with a cumulative reduction of 54%, to optimize the microstructure and obtain a high-strength and tough titanium alloy tube blank; the optimized microstructure is: grain size 35μm, strip-shaped α clusters are interspersed, the width of the strip-shaped α is 1μm~3μm, and the maximum length is 15μm; Step 4: The high-strength and high-toughness titanium alloy tube blank obtained in Step 3 is subjected to solution treatment and aging heat treatment to obtain a high-strength and high-toughness titanium alloy tube with the target microstructure and excellent mechanical properties. The solution heat treatment process is as follows: holding at 60℃ below the β phase transformation point for 1 hour, followed by air cooling. The aging heat treatment process is as follows: holding at 550℃ for 4 hours, followed by air cooling. The target microstructure is as follows: the equiaxed α phase grain size is controlled at 2μm~8μm, the width of the short and coarse strip-shaped α phase is controlled at 1μm~4μm, and the strip-shaped α clusters and equiaxed α clusters are uniformly distributed.

[0023] According to the test results, the high-strength and high-toughness titanium alloy pipe prepared in this embodiment has a yield strength of 925 MPa, an elongation of 18%, and an impact energy of 58 J.

[0024] Example 3 This embodiment includes the following steps: Step 1: The high-strength and high-toughness titanium alloy ingot is subjected to multi-fire, multi-directional forging deformation using an upsetting and drawing process with a single deformation amount of 40%, to obtain a high-strength and high-toughness titanium alloy billet with a uniform α+β two-phase structure and an average grain size of 270μm; the high-strength and high-toughness titanium alloy ingot is composed of the following composition by mass percentage: Al 5.72%, Sn 1.04%, Zr 3.45%, Mo 1.11%, V 0.99%, Nb 3.19%, with the balance being Ti and unavoidable impurities; The process of multi-fire multi-directional forging deformation is as follows: the high-strength and high-toughness titanium alloy ingot is heated to 150°C, 90°C and 40°C above the β phase transformation point and subjected to three-fire three-directional upsetting and drawing forging, with a single deformation amount of 45%. Then the obtained forging is heated to 20°C below the β phase transformation point and subjected to two-fire three-directional upsetting and drawing forging, with a single deformation amount of 35%. After forging, it is water-cooled. Then the water-cooled forging is heated to 20°C below the β phase transformation point and subjected to one-fire drawing and lengthening forging, with a single deformation amount of 30%. After forging, it is air-cooled. Step 2: Using a skew rolling piercing process, the high-strength and high-toughness titanium alloy billet obtained in Step 1 is pierced and hot rolled at 70°C above the β phase transformation point to obtain a high-strength and high-toughness titanium alloy tube; the deformation amount of the piercing forming is 69%, and the deformation amount of the hot rolling is 62%; Step 3: The high-strength and tough titanium alloy tube obtained in Step 2 is kept at 60°C below the β phase transformation point for 1 hour, and then subjected to tension reduction processing, with a cumulative reduction of 53%, to optimize the microstructure and obtain a high-strength and tough titanium alloy tube blank; the optimized microstructure is: grain size 38μm, strip-shaped α clusters are interspersed, the width of the strip-shaped α is 1μm~3μm, and the maximum length is 19μm; Step 4: The high-strength and high-toughness titanium alloy tube blank obtained in Step 3 is subjected to solution treatment and aging heat treatment to obtain a high-strength and high-toughness titanium alloy tube with the target microstructure and excellent mechanical properties. The solution heat treatment process is as follows: holding at 40℃ below the β phase transformation point for 1 hour, followed by air cooling. The aging heat treatment process is as follows: holding at 600℃ for 4 hours, followed by air cooling. The target microstructure is as follows: the equiaxed α phase grain size is controlled at 2μm~8μm, the width of the short and coarse strip-shaped α phase is controlled at 1μm~4μm, and the strip-shaped α clusters and equiaxed α clusters are uniformly distributed.

[0025] According to the test results, the high-strength and high-toughness titanium alloy pipe prepared in this embodiment has a yield strength of 926 MPa, an elongation of 16.5%, and an impact energy of 51.2 J.

[0026] Example 4 This embodiment includes the following steps: Step 1: The high-strength and high-toughness titanium alloy ingot is subjected to multi-fire, multi-directional forging deformation using an upsetting and drawing process with a single deformation amount of 50%, to obtain a high-strength and high-toughness titanium alloy billet with a uniform α+β two-phase structure and an average grain size of 300μm; the titanium alloy ingot is composed of the following composition by mass percentage: Al 5.72%, Sn 1.04%, Zr 3.45%, Mo 1.11%, V 0.99%, Nb 3.19%, with the balance being Ti and unavoidable impurities; The process of multi-fire multi-directional forging deformation is as follows: the high-strength and high-toughness titanium alloy ingot is heated to 150°C, 90°C and 40°C above the β phase transformation point and subjected to three-fire three-directional upsetting and drawing forging, with a single deformation amount of 50%. Then the obtained forging is heated to 20°C below the β phase transformation point and subjected to two-fire three-directional upsetting and drawing forging, with a single deformation amount of 30%. After forging, it is water-cooled. Then the water-cooled forging is heated to 20°C below the β phase transformation point and subjected to one-fire drawing and lengthening forging, with a single deformation amount of 30%. After forging, it is air-cooled. Step 2: Using a skew rolling piercing process, the high-strength and high-toughness titanium alloy billet obtained in Step 1 is pierced and hot rolled at 80°C above the β phase transformation point to obtain a high-strength and high-toughness titanium alloy tube; the deformation amount of the piercing forming is 70%, and the deformation amount of the hot rolling is 60%. Step 3: The high-strength and tough titanium alloy tube obtained in Step 2 is kept at 60°C below the β phase transformation point for 1 hour, and then subjected to tension reduction processing with a cumulative reduction of 55% to optimize the microstructure and obtain a high-strength and tough titanium alloy tube blank. The optimized microstructure is as follows: grain size 40μm, strip-shaped α clusters are interspersed, strip-shaped α width is 1μm~3μm, and maximum length is 20μm. Step 4: The high-strength and high-toughness titanium alloy tube blank obtained in Step 3 is subjected to solution treatment and aging heat treatment to obtain a high-strength and high-toughness titanium alloy tube with the target microstructure and excellent mechanical properties. The solution heat treatment process is as follows: holding at 30℃ below the β phase transformation point for 2 hours and then air cooling. The aging heat treatment process is as follows: holding at 550℃ for 4 hours and then air cooling. The target microstructure is as follows: the equiaxed α phase grain size is controlled at 2μm~8μm, the width of the short and coarse strip-shaped α phase is controlled at 1μm~4μm, and the strip-shaped α clusters and equiaxed α clusters are uniformly distributed.

[0027] According to the test results, the high-strength and high-toughness titanium alloy pipe prepared in this embodiment has a yield strength of 930 MPa, an elongation of 16.5%, and an impact energy of 50.6 J.

[0028] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for controlling the microstructure and properties of high-strength and high-toughness titanium alloy tubing, characterized in that, The method includes the following steps: Step 1: Perform multi-fire, multi-directional forging deformation on the high-strength and high-toughness titanium alloy ingot, using an upsetting and drawing process with a single deformation amount of 30%~50%, to obtain a high-strength and high-toughness titanium alloy billet with a uniform α+β two-phase structure and an average grain size of no more than 300μm. Step 2: Using the skew rolling piercing process, the high-strength and high-toughness titanium alloy billet obtained in Step 1 is pierced and hot rolled at 50℃~80℃ above the β phase transformation point to obtain a high-strength and high-toughness titanium alloy tube. Step 3: Hold the high-strength and tough titanium alloy tube obtained in Step 2 at 30℃~60℃ below the β phase transformation point for 1h~2h, and then perform tension reduction processing, with a cumulative reduction of 50%~55%, to optimize the microstructure and obtain a high-strength and tough titanium alloy tube blank. Step 4: The high-strength and high-toughness titanium alloy tube blank obtained in Step 3 is subjected to solution treatment and aging heat treatment to obtain a high-strength and high-toughness titanium alloy tube with the target microstructure and excellent mechanical properties.

2. The method for controlling the microstructure and properties of a high-strength and high-toughness titanium alloy pipe according to claim 1, characterized in that, The multi-fire, multi-directional forging deformation process described in step one is as follows: the high-strength and high-toughness titanium alloy ingot is heated to 40°C~150°C above the β phase transformation point for three-fire, three-directional upsetting and drawing forging, with a single deformation amount of 40%~50%. Then, the obtained forging is heated to 10°C~20°C below the β phase transformation point for two-fire, three-directional upsetting and drawing forging, with a single deformation amount of 30%~40%. After forging, it is water-cooled. Then, the water-cooled forging is heated to 10°C~20°C below the β phase transformation point for one-fire drawing and elongation forging, with a single deformation amount of 30%. After forging, it is air-cooled.

3. The method for controlling the microstructure and properties of a high-strength and high-toughness titanium alloy pipe according to claim 1, characterized in that, The deformation amount of the piercing forming in step two is 60%~70%, and the deformation amount of the hot rolling is 60%~70%.

4. The method for controlling the microstructure and properties of a high-strength and high-toughness titanium alloy pipe according to claim 1, characterized in that, The optimized microstructure described in step three is as follows: grain size not greater than 40 μm, strip-shaped α clusters interspersed, strip-shaped α width 1 μm~3 μm, and length not exceeding 20 μm.

5. The method for controlling the microstructure and properties of a high-strength and high-toughness titanium alloy pipe according to claim 1, characterized in that, The solution heat treatment procedure in step four is as follows: hold at 40℃~60℃ below the β phase transformation point for 1h~2h, then air cool; the aging heat treatment procedure is as follows: hold at 500℃~600℃ for 4h, then air cool.

6. The method for controlling the microstructure and properties of a high-strength and high-toughness titanium alloy pipe according to claim 1, characterized in that, The target microstructure described in step four is as follows: the size of equiaxed α phase grains is controlled at 2μm~8μm, the width of coarse and short strip-shaped α is controlled at 1μm~4μm, and the strip-shaped α clusters and equiaxed α clusters are evenly distributed.

7. The method for controlling the microstructure and properties of a high-strength and high-toughness titanium alloy tube according to claim 1, characterized in that, The superior mechanical properties mentioned in step four are: the high-strength and high-toughness titanium alloy pipe has a yield strength of over 910 MPa, an elongation of over 16%, and an impact energy of over 50 J.

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