Preparation method of high-toughness corrosion-resistant titanium alloy pipe

Abstract

The invention discloses a preparation method of a high-toughness corrosion-resistant titanium alloy pipe, which comprises the following steps of: 1, sequentially carrying out multi-heating forging deformation and one-time precision forging deformation on a titanium alloy cast ingot to obtain a titanium alloy bar blank; 2, machining the titanium alloy bar blank into an extrusion blank, and carrying out sheath extrusion to obtain an extrusion pipe blank; and thirdly, the extruded pipe blank is subjected to heat treatment, and the high-toughness corrosion-resistant titanium alloy pipe is obtained. According to the method, the titanium alloy cast ingot is prepared into the bar blank through the efficient fine grain forging and precision forging method, then the titanium alloy extrusion blank is machined, the pipe blank is prepared through extrusion, and finally the titanium alloy pipe is obtained through heat treatment, so that it is effectively guaranteed that the titanium alloy pipe has the excellent structure and performance, and the requirements for high toughness and corrosion resistance of the oil and gas exploration service environment are met; and the technological process is simple, and the cost is low.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloys, and in particular relates to a method for preparing a high-strength, toughness, and corrosion-resistant titanium alloy pipe. Background Art

[0002] Titanium and titanium alloys have received extensive attention in the fields of marine engineering, petrochemicals, etc. due to their excellent specific strength and corrosion resistance. The demand for high-strength, high-toughness, and high-corrosion-resistant titanium alloy pipes for marine engineering is increasing year by year. The current high-strength, high-toughness, and corrosion-resistant titanium alloys in China are still in the research and trial production stage, and the relevant pipe preparation technology is still immature and has not been able to obtain stable engineering applications.

[0003] At present, there are many preparation methods for high-strength and toughness titanium alloy pipes and excellent performance has been achieved, but there are still limitations, and no relevant data on the corrosion resistance of the pipes has been found. Patent No. CN109706344A discloses a titanium alloy pipe with a yield strength of 935MPa, a tensile strength of 1005MPa, a transverse elongation of 15%, and a full-size Charpy V-type impact energy of 49J; Patent No. CN111593230A discloses a titanium alloy pipe with a yield strength of R 0.2 ≥933MPa, tensile strength Rm ≥1051MPa, elongation δ ≥10%, impact energy AKV ≥60J. The pipes prepared by these process methods have good mechanical properties, but their service environment is mostly a high-strength and tough environment that requires bearing capacity. For titanium alloys for oil pipes under complex oil exploration and production service conditions, the material is not only required to have higher strength and excellent impact resistance, but also requires the pipe to have corrosion resistance in harsh environments.

[0004] The patent with publication number CN117802351A discloses a high-strength, corrosion-resistant titanium alloy pipe and its preparation method, but does not elaborate on the impact toughness of the material. As we all know, high-strength titanium alloy pipes are affected by temperature, stress, etc. during the forming process, and it is very difficult to accurately control their formability and organization. The addition of corrosion-resistant alloy elements will cause the formability of the pipe to be further reduced. The existing process is difficult to balance the control of the pipe shape and microstructure of difficult-to-deform titanium alloys. Coordinating the pipe preparation process parameters and microstructure is the difficulty for my country's titanium enterprises to prepare high-strength, toughness, and corrosion-resistant titanium alloy pipes. The current preparation of high-strength, toughness, and corrosion-resistant titanium alloy pipes in China is in the exploratory stage, and no generally applicable reliable technology has been formed.

[0005] The patent with publication number CN107541615A discloses a titanium alloy for marine engineering, which has good corrosion resistance and welding performance. The alloy has more beneficial strength and toughness than traditional marine titanium alloys, and has excellent corrosion resistance, and has great application prospects. However, due to the addition of corrosion-resistant elements such as Zr and Mo, the material has high deformation resistance in the two-phase region and is difficult to form. Therefore, exploring the preparation method of this new type of high-strength and tough corrosion-resistant titanium alloy pipe is of great significance for improving the preparation technology of high-performance titanium alloy pipes for marine engineering in my country and expanding the application of titanium alloy pipes. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing high-strength, toughness and corrosion-resistant titanium alloy pipes in view of the deficiencies of the above-mentioned prior art. The method prepares titanium alloy ingots into rod blanks by efficient fine-grain forging and precision forging methods, then processes titanium alloy extrusion blanks, prepares tube blanks by extrusion, and finally obtains titanium alloy pipes by heat treatment, which effectively ensures that the titanium alloy pipes have excellent structure and performance, meet the high strength, toughness and corrosion resistance requirements of the oil and gas exploration and production service environment, and solves the lack of reliable high-strength, toughness and corrosion-resistant titanium alloy pipe preparation process in the prior art.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a high-strength, tough and corrosion-resistant titanium alloy pipe, characterized in that the method comprises the following steps:

[0008] Step 1, subjecting a titanium alloy ingot to multiple forging deformations and one fine forging deformation in sequence to obtain a titanium alloy bar blank; the titanium alloy ingot is composed of the following components in mass percentage: Al 6.0% to 6.7%, Sn 0.5% to 2.0%, Zr 3.5% to 4.5%, Mo 1% to 1.15%, V 0.5% to 1.5%, Nb 2.0% to 3.1%, and the remainder is Ti and unavoidable impurities;

[0009] Step 2: machining the titanium alloy bar blank obtained in step 1 into an extrusion blank, and performing sheath extrusion to obtain an extruded tube blank;

[0010] Step 3: heat-treating the extruded tube obtained in step 2 to obtain a high-strength, toughness, and corrosion-resistant titanium alloy tube; the yield strength of the titanium alloy tube is not less than 900 MPa, the elongation is not less than 10%, and the impact energy at -20°C is not less than 50 J. According to the NACE TM0177-2016 test standard, a stress corresponding to 76% of the nominal yield strength is applied in test solution A for testing. After 720 hours, the high-strength and corrosion-resistant titanium alloy tube does not break.

[0011] The above-mentioned method for preparing a high-strength, toughness and corrosion-resistant titanium alloy pipe is characterized in that the process of multi-fire forging deformation described in step one is: heating the titanium alloy ingot to 50°C to 90°C above the β phase transformation point temperature for two-fire three-time reversing upsetting forging, with a single deformation amount of 30% to 40%; then heating the deformed forging to 10°C to 20°C above the β phase transformation point temperature for two-fire three-time reversing upsetting forging, with a single deformation amount of 30%, and water cooling after forging; then heating the deformed forging to 10°C to 20°C below the β phase transformation point temperature for one-fire conventional forging, with a single deformation amount of 30%, and water cooling after forging.

[0012] The above-mentioned method for preparing a high-strength, toughness and corrosion-resistant titanium alloy pipe is characterized in that the process of the single fine forging deformation in step one is: heating the titanium alloy forging obtained by multiple forging deformations to a temperature 10°C to 20°C below the β phase transformation point and then performing fine forging deformation, and the deformation amount of the fine forging deformation is not less than 40%.

[0013] The above-mentioned method for preparing a high-strength, toughness and corrosion-resistant titanium alloy pipe is characterized in that the process of mechanically processing the rod blank into an extruded blank in step 2 is: the rod blank machine is added to the extruded blank with an outer diameter of φ181mm and an inner diameter of φ79mm, and the outer diameter tolerance is -1mm~0mm, and one end of the extruded blank is chamfered R10~15.

[0014] The above-mentioned method for preparing a high-strength, tough and corrosion-resistant titanium alloy pipe is characterized in that the sheath extrusion process in step 2 is:

[0015] Step 201, coating the extruded blank with asbestos and copper to obtain a coated extruded blank;

[0016] Step 202, heating the jacketed extrusion blank obtained in step 201 in an induction heating furnace and keeping the temperature for 60 minutes; the heating temperature is 10°C below the β phase transition point temperature to 40°C above the β phase transition point temperature;

[0017] Step 203, placing the heated and heat-insulated extruded billet in step 202 on an extruder for extrusion, using an extrusion barrel with an inner diameter of φ185 mm, a preheating temperature of 200°C, and applying a high-temperature lubricant, an extrusion ratio of 7.3 to 10.1, and an extrusion speed of 35 mm / s to 40 mm / s.

[0018] The above-mentioned method for preparing a high-strength, toughness and corrosion-resistant titanium alloy pipe is characterized in that the heat treatment described in step three includes solution heat treatment and aging heat treatment, wherein the system of solution heat treatment is: keeping warm at 50°C to 80°C below the β phase transformation point for 1h to 2h, air cooling, and the system of aging heat treatment is: keeping warm at 550°C to 600°C for 4h, air cooling.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The present invention first provides the basic properties of titanium alloy materials by precisely controlling the composition of titanium alloy, and then prepares rod blanks through multiple forging deformations and one fine forging deformation, effectively refining the material structure grains, providing guarantee for subsequent extrusion deformation, and forming a gradient fine grain layer on the surface of the fully deformed forging by fine forging deformation, which is beneficial to improving the surface deformation quality of the extruded blank after subsequent extrusion deformation, and then through coating extrusion, reducing the contact temperature drop loss during the extrusion process, and finally obtaining the titanium alloy pipe through heat treatment. This preparation process effectively ensures that the titanium alloy pipe has excellent structure and performance, meets the high strength, toughness and corrosion resistance requirements of the oil and gas exploration and production service environment, and has a simple process flow and low cost.

[0021] 2. The present invention controls the deformation mode, deformation amount and deformation temperature of multi-fire forging deformation, effectively and evenly refines the grain size of the forging, and retains the fine-grained structure by means of water cooling after forging, providing a tissue basis for subsequent forging.

[0022] 3. The present invention controls the temperature and deformation amount of a single precision forging deformation, thereby ensuring the optimal organizational structure on the one hand and obtaining a surface fine-grained layer on the other hand, thereby improving the coordination of surface organizational deformation during the extrusion process, reducing surface cracking, and improving surface quality.

[0023] 4. The present invention adopts composite coating means and precise matching of extrusion dimensions, combined with control of extrusion temperature, extrusion barrel, extrusion process parameters and heat treatment parameters, to effectively reduce the extrusion temperature drop and ensure the acquisition of titanium alloy pipes with excellent performance.

[0024] The technical solution of the present invention is further described in detail below through embodiments. DETAILED DESCRIPTION

[0025] Example 1

[0026] This embodiment includes the following steps:

[0027] Step 1, subjecting a titanium alloy ingot to multiple forging deformations and one fine forging deformation in sequence to obtain a titanium alloy bar blank; the titanium alloy ingot is composed of the following components in mass percentage: Al 6.0%, Sn 1.02%, Zr 3.59%, Mo 1.09%, V 1.0%, Nb 2.88%, and the remainder is Ti and unavoidable impurities;

[0028] The multi-fire forging deformation process is as follows: heating the titanium alloy ingot to 90°C above the β phase transformation point temperature to perform one-fire three-way reversing upsetting forging, with a single deformation amount of 40%, then heating the deformed forging to 50°C above the β phase transformation point temperature to perform one-fire three-way reversing upsetting forging, with a single deformation amount of 30%; then heating the deformed forging to 20°C above the β phase transformation point temperature to perform two-fire three-way reversing upsetting forging, with a single deformation amount of 30%, and water cooling after forging; then heating the deformed forging to 10°C below the β phase transformation point temperature to perform one-fire conventional forging, with a single deformation amount of 30%, and water cooling after forging;

[0029] The process of the one-time fine forging deformation is: heating the titanium alloy forging obtained by multiple forging deformation to a temperature 10°C below the β phase transformation point and then performing fine forging deformation, wherein the deformation amount of the fine forging deformation is 47%;

[0030] Step 2: machining the titanium alloy bar blank obtained in step 1 into an extrusion blank, and performing sheath extrusion to obtain an extruded tube blank;

[0031] The process of machining the rod blank into the extrusion blank is as follows: the rod blank is machined into an extrusion blank with an outer diameter of φ180 mm and an inner diameter of φ79 mm, and the outer diameter tolerance is -0.5 mm, and one end of the extrusion blank is chamfered by R15;

[0032] The process of the sleeve extrusion is:

[0033] Step 201, coating the extruded blank with asbestos and copper to obtain a coated extruded blank;

[0034] Step 202, heating the jacketed extrusion blank obtained in step 201 to a temperature 10°C below the β phase transition point in an induction heating furnace and keeping the temperature for 60 minutes;

[0035] Step 203, placing the heated and heat-insulated jacketed extrusion blank in step 202 on an extruder for extrusion, using an extrusion barrel with an inner diameter of φ185 mm, a preheating temperature of 200° C., applying a high-temperature lubricant, an extrusion ratio of 7.3, and an extrusion speed of 35 mm / s;

[0036] Step three, heat treating the extruded tube obtained in step two to obtain a high-strength, toughness, and corrosion-resistant titanium alloy tube; the heat treatment includes solution heat treatment and aging heat treatment, wherein the solution heat treatment system is: keeping at 50°C below the β phase transformation point for 2 hours, air cooling, and the aging heat treatment system is: keeping at 550°C for 4 hours, air cooling.

[0037] After testing, the yield strength of the titanium alloy pipe prepared in this embodiment is 926 MPa, the elongation is 13.5%, and the impact energy at -20°C is 53.8 J. According to the NACE TM0177-2016 test standard, a stress corresponding to 76% of the nominal yield strength is applied in test solution A for testing. After 720 hours, the high-strength and corrosion-resistant titanium alloy pipe does not break.

[0038] Example 2

[0039] This embodiment includes the following steps:

[0040] Step 1, subjecting a titanium alloy ingot to multiple forging deformations and one fine forging deformation in sequence to obtain a titanium alloy bar blank; the titanium alloy ingot is composed of the following components in mass percentage: Al 6.03%, Sn 1.02%, Zr 3.65%, Mo1.08%, V 1.0%, Nb 2.87%, and the remainder is Ti and unavoidable impurities;

[0041] The multi-fire forging deformation process is as follows: heating the titanium alloy ingot to 90°C above the β phase transformation point temperature to perform one-fire three-way reversing upsetting forging, with a single deformation amount of 40%, then heating the deformed forging to 50°C above the β phase transformation point temperature to perform one-fire three-way reversing upsetting forging, with a single deformation amount of 30%; then heating the deformed forging to 20°C above the β phase transformation point temperature to perform two-fire three-way reversing upsetting forging, with a single deformation amount of 30%, and water cooling after forging; then heating the deformed forging to 20°C below the β phase transformation point temperature to perform one-fire conventional forging, with a single deformation amount of 30%, and water cooling after forging;

[0042] The process of the one-time fine forging deformation is: heating the titanium alloy forging obtained by multiple forging deformation to a temperature 20°C below the β phase transformation point and then performing fine forging deformation, wherein the deformation amount of the fine forging deformation is 42%;

[0043] Step 2: machining the titanium alloy bar blank obtained in step 1 into an extrusion blank, and performing sheath extrusion to obtain an extruded tube blank;

[0044] The process of machining the rod blank into the extrusion blank is as follows: the rod blank is machined into an extrusion blank with an outer diameter of φ181 mm and an inner diameter of φ79 mm, and the outer diameter tolerance is -1 mm, and one end of the extrusion blank is chamfered by R10;

[0045] The process of the sleeve extrusion is:

[0046] Step 201, coating the extruded blank with asbestos and copper to obtain a coated extruded blank;

[0047] Step 202, heating the jacketed extrusion blank obtained in step 201 to a temperature 40°C above the β phase transition point in an induction heating furnace and keeping the temperature for 60 minutes;

[0048] Step 203, placing the heated and heat-insulated jacketed extrusion blank in step 202 on an extruder for extrusion, using an extrusion barrel with an inner diameter of φ185 mm, a preheating temperature of 200° C., applying a high-temperature lubricant, an extrusion ratio of 10.1, and an extrusion speed of 40 mm / s;

[0049] Step three, heat treating the extruded tube obtained in step two to obtain a high-strength, toughness, and corrosion-resistant titanium alloy tube; the heat treatment includes solution heat treatment and aging heat treatment, wherein the solution heat treatment system is: keeping at 80°C below the β phase transformation point for 2 hours, air cooling, and the aging heat treatment system is: keeping at 600°C for 4 hours, air cooling.

[0050] After testing, the yield strength of the titanium alloy pipe prepared in this embodiment is 906MPa, the elongation is 11%, and the impact energy at -20°C is 58J. According to the NACE TM0177-2016 test standard, a stress corresponding to 76% of the nominal yield strength is applied in test solution A for testing. After 720 hours, the high-strength and corrosion-resistant titanium alloy pipe does not break.

[0051] Example 3

[0052] This embodiment includes the following steps:

[0053] Step 1, subjecting a titanium alloy ingot to multiple forging deformations and one fine forging deformation in sequence to obtain a titanium alloy bar blank; the titanium alloy ingot is composed of the following components in mass percentage: Al 6.7%, Sn 1.0%, Zr 4.5%, Mo 1.15%, V 1.5%, Nb 3.1%, and the remainder is Ti and unavoidable impurities;

[0054] The multi-fire forging deformation process is as follows: heating the titanium alloy ingot to 90°C above the β phase transformation point temperature to perform one-fire three-way reversing upsetting forging, with a single deformation amount of 40%, then heating the deformed forging to 60°C above the β phase transformation point temperature to perform one-fire three-way reversing upsetting forging, with a single deformation amount of 30%; then heating the deformed forging to 10°C above the β phase transformation point temperature to perform two-fire three-way reversing upsetting forging, with a single deformation amount of 30%, and water cooling after forging; then heating the deformed forging to 10°C below the β phase transformation point temperature to perform one-fire conventional forging, with a single deformation amount of 30%, and water cooling after forging;

[0055] The process of the one-time fine forging deformation is: heating the titanium alloy forging obtained by multiple forging deformation to a temperature 10°C below the β phase transformation point and then performing fine forging deformation, wherein the deformation amount of the fine forging deformation is 45%;

[0056] Step 2: machining the titanium alloy bar blank obtained in step 1 into an extrusion blank, and performing sheath extrusion to obtain an extruded tube blank;

[0057] The process of machining the rod blank into the extrusion blank is as follows: the rod blank is machined into an extrusion blank with an outer diameter of φ180 mm and an inner diameter of φ79 mm, and the outer diameter tolerance is -0.5 mm, and one end of the extrusion blank is chamfered by R15;

[0058] The process of the sleeve extrusion is:

[0059] Step 201, coating the extruded blank with asbestos and copper to obtain a coated extruded blank;

[0060] Step 202, heating the jacketed extrusion blank obtained in step 201 in an induction heating furnace to a temperature 20°C above the β phase transition point and keeping the temperature for 60 minutes;

[0061] Step 203, placing the heated and heat-insulated jacketed extrusion blank in step 202 on an extruder for extrusion, using an extrusion barrel with an inner diameter of φ185 mm, a preheating temperature of 200° C., applying a high-temperature lubricant, an extrusion ratio of 8.2, and an extrusion speed of 38 mm / s;

[0062] Step three, heat treating the extruded tube obtained in step two to obtain a high-strength, toughness, and corrosion-resistant titanium alloy tube; the heat treatment includes solution heat treatment and aging heat treatment, wherein the solution heat treatment system is: keeping at 60°C below the β phase transformation point for 1 hour, air cooling, and the aging heat treatment system is: keeping at 550°C for 4 hours, air cooling.

[0063] After testing, the yield strength of the titanium alloy pipe prepared in this embodiment is 921 MPa, the elongation is 12.5%, and the impact energy at -20°C is 52.6 J. According to the NACE TM0177-2016 test standard, a stress corresponding to 76% of the nominal yield strength is applied in test solution A for testing. After 720 hours, the high-strength and corrosion-resistant titanium alloy pipe does not break.

[0064] Example 4

[0065] This embodiment includes the following steps:

[0066] Step 1, subjecting a titanium alloy ingot to multiple forging deformations and one fine forging deformation in sequence to obtain a titanium alloy bar blank; the titanium alloy ingot is composed of the following components in mass percentage: Al 6.15%, Sn 2.0%, Zr 3.5%, Mo 1.0%, V 0.5%, Nb 2.0%, and the remainder is Ti and unavoidable impurities;

[0067] The multi-fire forging deformation process is as follows: heating the titanium alloy ingot to 90°C above the β phase transformation point temperature to perform one-fire three-way reversing upsetting forging, with a single deformation amount of 40%, then heating the deformed forging to 60°C above the β phase transformation point temperature to perform one-fire three-way reversing upsetting forging, with a single deformation amount of 30%; then heating the deformed forging to 10°C above the β phase transformation point temperature to perform two-fire three-way reversing upsetting forging, with a single deformation amount of 30%, and water cooling after forging; then heating the deformed forging to 15°C below the β phase transformation point temperature to perform one-fire conventional forging, with a single deformation amount of 30%, and water cooling after forging;

[0068] The process of the one-time fine forging deformation is: heating the titanium alloy forging obtained by multiple forging deformation to a temperature 10°C below the β phase transformation point and then performing fine forging deformation, wherein the deformation amount of the fine forging deformation is 46%;

[0069] Step 2: machining the titanium alloy bar blank obtained in step 1 into an extrusion blank, and performing sheath extrusion to obtain an extruded tube blank;

[0070] The process of machining the rod blank into the extrusion blank is as follows: the rod blank is machined into an extrusion blank with an outer diameter of φ180 mm and an inner diameter of φ79 mm, and the outer diameter tolerance is 0 mm, and one end of the extrusion blank is chamfered R12;

[0071] The process of the sleeve extrusion is:

[0072] Step 201, coating the extruded blank with asbestos and copper to obtain a coated extruded blank;

[0073] Step 202, heating the jacketed extrusion blank obtained in step 201 in an induction heating furnace to a temperature 10°C above the β phase transition point and keeping the temperature for 60 minutes;

[0074] Step 203, placing the heated and heat-insulated jacketed extrusion blank in step 202 on an extruder for extrusion, using an extrusion barrel with an inner diameter of φ185 mm, a preheating temperature of 200° C., and applying a high-temperature lubricant, an extrusion ratio of 9.3, and an extrusion speed of 36 mm / s;

[0075] Step three, heat treating the extruded tube obtained in step two to obtain a high-strength, toughness, and corrosion-resistant titanium alloy tube; the heat treatment includes solution heat treatment and aging heat treatment, wherein the solution heat treatment system is: keeping at 70°C below the β phase transformation point for 2 hours, air cooling, and the aging heat treatment system is: keeping at 580°C for 4 hours, air cooling.

[0076] After testing, the yield strength of the titanium alloy pipe prepared in this embodiment is 913 MPa, the elongation is 16.5%, and the impact energy at -20°C is 53.3 J. According to the NACE TM0177-2016 test standard, a stress corresponding to 76% of the nominal yield strength is applied in test solution A for testing. After 720 hours, the high-strength and corrosion-resistant titanium alloy pipe does not break.

[0077] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a high-strength, tough, and corrosion-resistant titanium alloy pipe, characterized in that: The method comprises the following steps: Step 1, subjecting a titanium alloy ingot to multiple forging deformations and one fine forging deformation in sequence to obtain a titanium alloy bar blank; the titanium alloy ingot is composed of the following components in mass percentage: Al 6.0% to 6.7%, Sn 0.5% to 2.0%, Zr 3.5% to 4.5%, Mo 1% to 1.15%, V 0.5% to 1.5%, Nb 2.0% to 3.1%, and the remainder is Ti and unavoidable impurities; Step 2: machining the titanium alloy bar blank obtained in step 1 into an extrusion blank, and performing sheath extrusion to obtain an extruded tube blank; Step 3: heat-treating the extruded tube obtained in step 2 to obtain a high-strength, toughness, and corrosion-resistant titanium alloy tube; the yield strength of the titanium alloy tube is not less than 900 MPa, the elongation is not less than 10%, and the impact energy at -20°C is not less than 50 J. According to the NACETM0177-2016 test standard, a stress corresponding to 76% of the nominal yield strength is applied in test solution A for testing. After 720 hours, the high-strength and corrosion-resistant titanium alloy tube does not break.

2. The method for preparing a high-strength, toughness and corrosion-resistant titanium alloy pipe according to claim 1, characterized in that: The process of multi-fire forging deformation in step 1 is: heating the titanium alloy ingot to 50°C to 90°C above the β phase transformation point temperature for two-fire three-time reversing upsetting forging, with a single deformation amount of 30% to 40%; then heating the deformed forging to 10°C to 20°C above the β phase transformation point temperature for two-fire three-time reversing upsetting forging, with a single deformation amount of 30%, and water cooling after forging; then heating the deformed forging to 10°C to 20°C below the β phase transformation point temperature for one-fire conventional forging, with a single deformation amount of 30%, and water cooling after forging.

3. The method for preparing a high-strength, toughness and corrosion-resistant titanium alloy pipe according to claim 1, characterized in that: The process of the one-time fine forging deformation in step 1 is: heating the titanium alloy forging obtained by multiple forging deformation to a temperature 10°C to 20°C below the β phase transformation point and then performing fine forging deformation, and the deformation amount of the fine forging deformation is not less than 40%.

4. The method for preparing a high-strength, toughness and corrosion-resistant titanium alloy pipe according to claim 1, characterized in that: The process of machining the rod blank into the extrusion blank in step 2 is: the rod blank is machined into an extrusion blank with an outer diameter of φ181mm and an inner diameter of φ79mm, and the outer diameter tolerance is -1mm to 0mm, and one end of the extrusion blank is chamfered R10 to 15.

5. The method for preparing a high-strength, toughness, corrosion-resistant titanium alloy pipe according to claim 1, characterized in that: The process of the package extrusion in step 2 is: Step 201, coating the extruded blank with asbestos and copper to obtain a coated extruded blank; Step 202, heating the jacketed extrusion blank obtained in step 201 in an induction heating furnace and keeping the temperature for 60 minutes; the heating temperature is 10°C below the β phase transition point temperature to 40°C above the β phase transition point temperature; Step 203, placing the heated and heat-insulated extruded billet in step 202 on an extruder for extrusion, using an extrusion barrel with an inner diameter of φ185 mm, a preheating temperature of 200°C, and applying a high-temperature lubricant, an extrusion ratio of 7.3 to 10.1, and an extrusion speed of 35 mm / s to 40 mm / s.

6. The method for preparing a high-strength, toughness, corrosion-resistant titanium alloy pipe according to claim 1, characterized in that: The heat treatment in step three includes solution heat treatment and aging heat treatment, wherein the system of solution heat treatment is: keeping at 50℃~80℃ below the β phase transformation point for 1h~2h, air cooling, and the system of aging heat treatment is: keeping at 550℃~600℃ for 4h, air cooling.