A method for manufacturing a powder metallurgy titanium alloy T-shaped tee pipe fitting

Abstract

The present application relates to the technical fields of plastic processing forming of metal materials, and particularly relates to a preparation method of a powder metallurgy titanium alloy T-shaped tee pipe fitting. The preparation method of the powder metallurgy titanium alloy T-shaped tee pipe fitting comprises the steps of powder metallurgy blank preparation, mold preparation, anti-oxidation coating brushing, radial extrusion forming, semi-finished product machining, tee shaping, finished product machining, vacuum heat treatment and surface treatment. The preparation method of the powder metallurgy titanium alloy T-shaped tee pipe fitting has the advantages that an elliptical hollow pipe blank is prepared by using the powder metallurgy method, the titanium alloy T-shaped tee is prepared by using the mold radial extrusion and mold shaping method after local heating of the pipe blank, the fluidity is improved, the elongation is improved, the multi-pass forming is not needed, the forming efficiency is improved, and the cracking at the branch pipe position caused by the factors such as local work hardening and stress concentration in the forming process is avoided.

Description

Technical Field

[0001] This invention relates to the field of plastic forming technology of metal materials, and in particular to a method for preparing a powder metallurgy titanium alloy T-shaped tee fitting. Background Technology

[0002] Titanium alloys possess excellent properties such as low density, high strength, strong corrosion resistance, and good weldability. Their corrosion resistance in seawater is particularly outstanding, earning them the title of "marine metal," making them an ideal metallic material for shipbuilding and marine engineering. The application of titanium alloys in marine seawater pipelines can reduce the corrosion design margin in pipeline wall thickness, thereby achieving overall weight reduction in the pipeline system, which is of great significance for lightweight design of ship systems. Tees, as one of the important accessories in seawater pipeline systems, mainly serve the functions of diverting and converging flow. Their relatively simple structure makes them an important connecting accessory in seawater pipeline systems.

[0003] In existing technologies, room temperature hydraulic bulging is the main method for forming titanium alloy tees. For example, Chinese utility model patent CN205716176U discloses a titanium alloy tee pipe for petrochemical pipelines, belonging to the field of mechanical design technology. This titanium alloy tee pipe includes a main pipe and a branch pipe, with the main pipe located in the middle of the branch pipe, and the two are interconnected as a single pipe. The angle between the central axis of the main pipe and the central axis of the branch pipe is 90°; the main pipe includes a main pipe head and a main pipe body; the outer diameter of the main pipe head is larger than the outer diameter of the main pipe body, and the inner diameter of the main pipe head is the same as the inner diameter of the main pipe body. The branch pipe includes a branch pipe head and a branch pipe body; the outer diameter of the branch pipe head is larger than the outer diameter of the branch pipe body; the inner diameter of the branch pipe head is the same as the inner diameter of the branch pipe body. The main pipe head, main pipe body, branch pipe head, and branch pipe body are all cylindrical, and the inner and outer diameters of the main pipe head and the branch pipe head are the same; the inner and outer diameters of the main pipe body and the branch pipe body are the same. It uses metal pipes as blanks and injects a liquid medium into the sealed pipe blank using specialized tee forming equipment to generate high pressure. Simultaneously, axial thrust is applied to both ends of the pipe blank for material replenishment. Under the action of these two external forces, the titanium alloy tee is cold-formed. However, due to the high strength, poor fluidity, and low elongation of titanium alloy at room temperature, multiple forming passes are usually required, with intermediate annealing between each pass, resulting in low forming efficiency. Furthermore, during the forming process, factors such as localized work hardening and stress concentration can easily lead to cracking at the branch pipe locations, resulting in a low yield. Summary of the Invention

[0004] In view of this, the present invention aims to provide a method for preparing powder metallurgy titanium alloy T-type tee fittings. The method involves preparing an elliptical hollow tube blank using powder metallurgy, followed by localized heating of the tube blank, and then using radial extrusion and die shaping to prepare the titanium alloy T-type tee. This method solves the problems of low forming efficiency caused by the high strength, poor fluidity, and low elongation of titanium alloy materials at room temperature, which typically require multiple forming passes with intermediate annealing between each pass. Furthermore, the method addresses the issue of cracking at the branch pipe location due to localized work hardening and stress concentration during the forming process.

[0005] To address the above problems, this invention provides a method for preparing a powder metallurgy titanium alloy T-type tee fitting, comprising:

[0006] S100. Prepare titanium alloy powder according to the design requirements and material requirements. Load the prepared titanium alloy powder into a tube blank mold prepared according to the design requirements and vacuum the tube blank mold. Obtain the tube blank by hot isostatic pressing.

[0007] S200. Prepare a mold, the mold including an upper mold and a lower mold, an upper cavity is provided in the upper mold, a lower cavity is provided in the lower mold, after the upper mold and the lower cavity are fastened together, the upper cavity and the lower cavity are connected to form a mold cavity, the lower cavity is an arc-shaped groove that runs through the length direction of the lower mold, the upper cavity is T-shaped, and the upper cavity includes an arc-shaped groove that runs through the length direction of the upper mold and a through hole that runs through the thickness direction of the upper cavity;

[0008] The mold includes an extrusion molding mold and a shaping mold having the same structure;

[0009] S300. Apply anti-oxidation coating evenly to the inner and outer surfaces of the tube blank and then let it dry.

[0010] S400. The extrusion molding die is assembled on the press, the tube blank is placed in the lower cavity, the tube blank is heated to the preset extrusion temperature, and after the preset time of heat preservation, the press is started and the upper die is pressed down until the upper die and the lower die are in contact, and the tube blank forms the main tube section and the branch tube section connected to the main tube section.

[0011] S500: The main pipe is machined according to the design requirements, and the branch pipe is drawn to the pre-processed size to form a pre-processed tee pipe.

[0012] S600: Assemble the forming mold on the press, place the pre-processed tee pipe in the lower cavity, heat the pipe blank to the preset extrusion temperature, and after the preset time of heat preservation, start the press and press down the upper mold until the upper mold and the lower mold fit together to form a semi-finished tee pipe.

[0013] S700: Machining of semi-finished tee pipes to meet design requirements;

[0014] S800, Vacuum heat treatment is performed on the semi-finished tee pipe;

[0015] S900: Surface treatment is performed on the semi-finished tee pipe to form a finished tee pipe fitting.

[0016] Furthermore, in step S100,

[0017] The tube blank mold is an elliptical sleeve with the length of the major axis a = 1.5D and the length of the minor axis c = D, where D is the outer diameter of the main pipe of the tee fitting.

[0018] Furthermore, in step S100, the vacuum degree after evacuating the tube blank mold is no greater than 10. -2 Pa.

[0019] Furthermore, in step S100, the hot isostatic pressing requirements are: temperature of 900℃~1100℃, pressure of 100MPa~140MPa, and holding time of heat and pressure of 2-6h.

[0020] Furthermore, in step S200, the through hole and groove of the upper cavity are connected by a rounded transition, with a transition radius R of 25-35mm.

[0021] Furthermore, in step S200,

[0022] The extrusion molding die includes an upper extrusion die and a lower extrusion die. The upper extrusion die has a T-shaped upper extrusion cavity inside, and the lower extrusion die has a lower extrusion cavity inside. The centers of the upper extrusion cavity and the lower extrusion cavity are located outside the opposite end faces of the upper extrusion die and the lower extrusion die.

[0023] The shaping mold includes an upper shaping mold and a lower shaping mold. The upper shaping mold has a T-shaped upper shaping cavity inside, and the lower shaping mold has a lower shaping cavity inside. The centers of the upper shaping cavity and the lower shaping cavity are located on the opposite end faces of the upper shaping mold and the lower shaping mold.

[0024] Furthermore, in step S400, when the extrusion die is assembled onto the press, the center lines of the upper extrusion die and the lower extrusion die are aligned.

[0025] In step S600, when the forming mold is assembled onto the press, the center lines of the upper forming mold and the lower forming mold are aligned.

[0026] Furthermore, in steps S400 and S600, when the extrusion molding die or shaping die is assembled onto the press, the die is preheated to 200-300°C.

[0027] The preset extrusion temperature is 800-850℃, and the holding time is 5-10 minutes.

[0028] Furthermore, in steps S400 and S600, the molding process is carried out in at least two steps, with each step having a deformation amount of 20-40%.

[0029] Furthermore, in step S900, the surface treatment method includes:

[0030] The surface anti-oxidation coating of the tee fitting is removed by sandblasting, and the tee fitting is then ground.

[0031] Compared with existing technologies, the preparation method of the powder metallurgy titanium alloy T-type tee pipe fitting described in this invention has the following advantages:

[0032] The advantage of this technical solution is that it uses powder metallurgy to prepare elliptical hollow tube blanks. After local heating of the tube blanks, titanium alloy T-shaped tees are prepared by radial extrusion and shaping with a die. This improves fluidity and elongation, eliminates the need for multiple forming passes, improves forming efficiency, and avoids cracking at the branch pipe position caused by factors such as local work hardening and stress concentration during the forming process. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the preparation method of the powder metallurgy titanium alloy T-type tee pipe fitting according to an embodiment of the present invention;

[0034] Figure 2 This is a cross-sectional view of the tee fitting described in an embodiment of the present invention;

[0035] Figure 3 This is a cross-sectional view of the tube blank mold described in an embodiment of the present invention;

[0036] Figure 4 This is a cross-sectional view of the extrusion die in the elongation direction according to an embodiment of the present invention;

[0037] Figure 5 The extrusion molding die described in the embodiments of the present invention Figure 4 AA section view;

[0038] Figure 6 This is a cross-sectional view of the forming mold in the extension direction according to an embodiment of the present invention;

[0039] Figure 7 The shaping mold described in the embodiments of the present invention Figure 6 BB cross-sectional view.

[0040] Explanation of reference numerals in the attached figures:

[0041] 100-Tee fitting, 110-Main pipe section, 120-Branch pipe section, 200-Pipe blank mold, 300-Extrusion molding mold, 310-Lower extrusion mold, 311-Lower extrusion cavity, 320-Upper extrusion mold, 321-Upper extrusion cavity, 400-Shaping mold, 410-Lower shaping mold, 411-Lower shaping cavity, 420-Upper shaping mold, 421-Upper shaping cavity. Detailed Implementation

[0042] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0043] In this invention, the terms "first," "second," "upper," and "lower," etc., are used for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," "upper," or "lower" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. Where the technical solutions of the embodiments can be combined, they are all within the scope of protection claimed by this invention.

[0044] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0045] like Figure 1 As shown, a method for preparing a powder metallurgy titanium alloy T-type tee pipe fitting includes:

[0046] S100. Prepare titanium alloy powder according to the design and material requirements, such as... Figure 2 and Figure 3 As shown, the prepared titanium alloy powder is loaded into a tube blank mold 200 prepared according to the design requirements. The tube blank mold 200 is an elliptical sleeve with a major axis length a = 1.5D and a minor axis length c = D, where D is the outer diameter of the main pipe of the tee fitting 100. The tube blank mold 200 is then evacuated (vacuum degree not exceeding 10). -2 After Pa), the tube blank is obtained by hot isostatic pressing. The hot isostatic pressing requirements are: temperature 900℃~1100℃, pressure 100MPa~140MPa, and heat and pressure holding time 2-6h.

[0047] S200, such as Figures 4 to 7As shown, a mold is prepared, comprising an upper mold and a lower mold. The upper mold has an upper cavity, and the lower mold has a lower cavity. When the upper and lower molds are engaged, the upper and lower cavities communicate to form a mold cavity. The lower cavity is an arc-shaped groove extending along the length of the lower mold. The upper cavity is T-shaped and includes the arc-shaped groove extending along the length of the upper mold and a through hole extending along the thickness of the upper cavity. Preferably, the arc-shaped grooves of the lower and upper cavities have the same radius, and the through hole and groove of the upper cavity have a rounded transition with a radius R of 25–35 mm.

[0048] The mold includes an extrusion molding mold 300 and a shaping mold 400, both having the same structure.

[0049] As one embodiment, the extrusion molding die 300 includes an upper extrusion die 320 and a lower extrusion die 310. A T-shaped upper extrusion cavity 321 is provided inside the upper extrusion die 320, and a lower extrusion cavity 311 is provided inside the lower extrusion die 310. The centers of the upper extrusion cavity 321 and the lower extrusion cavity 311 are both located outside the opposite end faces of the upper extrusion die 320 and the lower extrusion die 310.

[0050] After the upper extrusion die 320 and the lower extrusion die 310 of the extrusion molding die 300 are engaged, when the arc-shaped grooves of the upper extrusion cavity 321 and the lower extrusion cavity 311 form a circular shape, a certain gap is formed between the opposite end faces of the upper extrusion die 320 and the lower extrusion die 310. The sleeve placed in the extrusion molding die 300 shortens its long axis after extrusion, but the main pipe 110 remains elliptical. The sleeve located at the through hole of the upper extrusion cavity 321 extends along the through hole into the through hole, initially forming the branch pipe 120 of the tee fitting 100.

[0051] The shaping mold 400 includes an upper shaping mold 420 and a lower shaping mold 410. The upper shaping mold 420 has a T-shaped upper shaping cavity 421 inside, and the lower shaping mold 410 has a lower shaping cavity 411 inside. The centers of the upper shaping cavity 421 and the lower shaping cavity 411 are located on the opposite end faces of the upper shaping mold 420 and the lower shaping mold 410.

[0052] After the upper forming mold 420 and the lower forming mold 410 of the forming mold 400 are engaged, when the arc-shaped grooves of the upper forming cavity 421 and the lower forming cavity 411 form a circular shape, the opposite end faces of the upper forming mold 420 and the lower forming mold 410 fit together. The sleeve placed in the forming mold 400 is pressed to compress the elliptical main pipe 110 into a roughly circular tube shape. The sleeve located at the through hole of the upper forming cavity 421 continues to extend into the through hole, eventually forming the branch pipe 120 of the tee fitting 100.

[0053] S300. Apply anti-oxidation coating evenly to the inner and outer surfaces of the tube blank and then let it dry.

[0054] S400. Assemble the extrusion die 300 onto the press, aligning the center lines of the upper extrusion die 320 and the lower extrusion die 310. As one embodiment, an alignment mark (not shown) is provided at the midpoint of the side surface along the length direction of the lower extrusion die 310 and at the midpoint of the side surface along the length direction of the upper extrusion die 320. For example, a triangular mark is provided on the same side surface of the upper extrusion die 320 and the lower extrusion die 310, with the two corners of the two triangles facing each other. By adjusting the positions of the upper extrusion die 320 and the lower extrusion die 310 so that the two corners are facing each other, the relative positions of the branch pipe 120 and the main pipe 110 are ensured during molding.

[0055] After aligning the centerlines of the upper extrusion die 320 and the lower extrusion die 310, ensuring the alignment of the main pipe sections, the dies are preheated to 200–300°C. The tube blank is placed in the lower extrusion cavity 311 and heated to the preset extrusion temperature. After a preset holding time, the press is started, and the upper extrusion die 320 is pressed down, forming the main pipe section 110 and the branch pipe section 120 connected to the main pipe section 110. The preset extrusion temperature is 800–850°C, and the holding time is 5–10 minutes. The forming process is carried out in at least two steps, with each step involving a deformation of 20–40%.

[0056] S500. According to the design requirements, the main pipe section 110 is machined and the branch pipe section 120 is drawn to the pre-processed size to form a pre-processed tee pipe.

[0057] Specifically, a scribe line is made at the top of the main pipe section 110, with the major axis dimension being 0.7D1 and the minor axis dimension being 0.6D1. The pipe is then machined to the target dimensions. The billet is then heated to the drawing temperature (800-850℃) and drawn in multiple passes. The mandrel dimensions are 0.6D1 to 1.1D1. D1 is the diameter of the branch pipe.

[0058] S600: Assemble the forming mold 400 onto the press, aligning the center lines of the upper forming mold 420 and the lower forming mold 410. As one embodiment, an alignment mark (not shown) is provided at the midpoint of the side surface along the length direction of the lower forming mold 410 and the midpoint of the side surface along the length direction of the upper forming mold 420. For example, a triangular mark is provided on the same side surface of the upper forming mold 420 and the lower forming mold 410, with the two corners of the two triangular marks facing each other. By adjusting the positions of the upper forming mold 420 and the lower forming mold 410, the two corners are aligned, ensuring the relative position of the branch pipe 120 and the main pipe 110 during forming. Adjusting the positions of the upper forming mold 420 and the lower forming mold 410 using the alignment marks ensures the alignment of the middle of the main pipe, and the mold is preheated to 200–300°C. The pre-processed tee pipe is placed in the lower forming cavity 411, and the pipe blank is heated to the preset extrusion temperature. After holding at this temperature for a preset time, the press is started, and the upper forming die 421 is pressed down until the upper forming die 420 and the lower forming die 410 are fitted together, forming a semi-finished tee pipe. The preset extrusion temperature is 800-850℃, and the holding time is 5-10 minutes. The forming process is carried out in at least two steps, with a deformation amount of 20-40% in each step.

[0059] S700. Machining of semi-finished tee pipes to design requirements. Machining of the two ends of the tee according to the product drawings of titanium alloy T-type tee pipe fittings, including: flat end face, machining of main pipe bevel, branch pipe bevel, etc.

[0060] S800. Vacuum heat treatment is performed on the semi-finished tee pipe. After the surface of the titanium alloy T-type tee pipe fitting 100 is coated with anti-oxidation coating, it is placed in a vacuum heat treatment furnace. The vacuum degree of the furnace is required to be no greater than 1×10-2Pa. The heating temperature is set to 600~650℃. After reaching the temperature, it is held for 30~60 minutes before being taken out of the furnace to ensure that the entire pipe fitting is heated evenly.

[0061] S900. The semi-finished tee fitting 100 is surface treated by sandblasting to remove the anti-oxidation coating on the surface of the tee fitting 100, and the tee fitting 100 is ground to form the finished tee fitting 100.

[0062] The following is a specific embodiment illustrating the preparation method of the powder metallurgy titanium alloy T-type tee fitting of the present invention.

[0063] The finished T-type tee fitting has a main pipe diameter D = 273mm, a main pipe length L = 432mm, a main pipe wall thickness t = 10mm, a branch pipe height H = 203mm, a branch pipe diameter D1 = 219mm, and a branch pipe wall thickness t1 = 10mm. Specifically:

[0064] S100, Powder Metallurgy Billet Preparation: Spherical powder of grade TA24 titanium alloy is used, and the particle size distribution is obtained by screening to obtain powder with a particle size distribution of 50um to 300um; an elliptical sleeve is prepared using carbon steel, the powder is placed in the sleeve, and then the sleeve is evacuated to a vacuum degree of 1×10-2 Pa. Then the evacuation port is sealed by welding, resulting in a steel sleeve containing titanium powder with an internal vacuum; the sleeve containing powder is then subjected to hot isostatic pressing. The hot isostatic pressing temperature is 920℃, the pressure is 120MPa, and the holding time is 5h. After exiting the furnace, an elliptical tube billet with dimensions of 409.5mm (major axis a) × 273.0mm (minor axis c) × 432mm (length) is obtained.

[0065] S200. Mold Preparation: The tee extrusion molding mold mainly consists of an upper mold and a lower mold. The upper and lower molds form a hollow cavity, manufactured according to the outer diameter dimensions of the main and branch pipes of the tee, and the dimensions of the transition arc. The transition radius R of the upper mold's concave corner is 30mm. Similarly, the tee forming mold mainly consists of an upper mold and a lower mold, see... Figure 4 The upper and lower molds form a hollow cavity, which is manufactured according to the outer diameter of the main and branch pipes of the tee and the dimensions of the transition arc. The radius R of the transition arc of the upper mold's concave part is 30mm.

[0066] S300, Apply anti-oxidation coating: Apply anti-oxidation coating evenly to the inner and outer surfaces of the powder metallurgy titanium alloy tube blank and let it dry.

[0067] S400 Radial Extrusion Molding: Assemble the extrusion die onto the press, ensuring the centerlines of the upper and lower dies are aligned. Preheat the die to 250℃. Place the powder metallurgy titanium alloy tube blank into the lower die and locally heat the blank at 800±10℃ for 5 minutes. Then operate the press, slowly pressing the upper die down at a speed of 7.5 mm / s until the upper and lower dies are in contact. The molding process is completed in three passes, with a deformation of 30% in each pass.

[0068] S500, Branch Pipe Partial Opening and Drawing Forming: The main pipe top area of ​​the above blank is marked and opened, with the major axis dimension being 153.3mm and the minor axis dimension being 134.4mm. The blank is machined to the target size. Then the blank is heated to the drawing temperature of 800℃±10℃ and drawn in three passes. The core mold dimensions are 134.4mm, 175.2mm and 240.9mm respectively.

[0069] S600, T-joint forming: Assemble the extrusion die onto the press, ensuring the center lines of the upper and lower dies are aligned, and preheat the die to 250℃. Place the drawn powder metallurgy titanium alloy tube blank into the lower die, and locally heat the blank at 800℃ for 5 minutes. Then operate the press, slowly pressing down at a speed of 7.5 mm / s until the upper and lower dies are in contact. The forming process is completed in two passes, with a deformation of 30% in each pass.

[0070] S700, Machining: Machining the two ends of the tee according to the product drawings of the titanium alloy T-type tee fitting, including: flat end face, machining the bevel of the main pipe, and the bevel of the branch pipe, etc.

[0071] S800, Vacuum heat treatment: After coating the surface of the titanium alloy T-type tee fitting with anti-oxidation coating, place it in a vacuum heat treatment furnace. The vacuum degree of the furnace should not exceed 1×10-2 Pa. Set the heating temperature to 620℃. After reaching the temperature, hold it at that temperature for 40 minutes before removing it from the furnace to ensure that the entire fitting is heated evenly.

[0072] S900 Surface Treatment: Sandblasting removes the anti-oxidation coating from the surface of the tee fitting using 40-mesh quartz sand. Simultaneously, the tee fitting is ground to ensure the quality of both its inner and outer surfaces.

[0073] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for preparing a powder metallurgy titanium alloy T-type tee pipe fitting, characterized in that, include: S100. Prepare titanium alloy powder according to the design requirements and material requirements. Load the prepared titanium alloy powder into a tube blank mold (200) prepared according to the design requirements and vacuum the tube blank mold (200). Obtain the tube blank by hot isostatic pressing. S200. Prepare a mold, the mold including an upper mold and a lower mold, an upper cavity is provided in the upper mold, a lower cavity is provided in the lower mold, after the upper mold and the lower mold are fastened together, the upper cavity and the lower cavity are connected to form a mold cavity, the lower cavity is an arc-shaped groove that runs through the length direction of the lower mold, the upper cavity is T-shaped, and the upper cavity includes an arc-shaped groove that runs through the length direction of the upper mold and a through hole that runs through the thickness direction of the upper cavity; The mold includes an extrusion molding mold and a shaping mold having the same structure; The extrusion molding die (300) includes an upper extrusion die (320) and a lower extrusion die (310). A T-shaped upper extrusion cavity (321) is provided inside the upper extrusion die (320), and a lower extrusion cavity (311) is provided inside the lower extrusion die (310). The centers of the upper extrusion cavity (321) and the lower extrusion cavity (311) are located outside the opposite end faces of the upper extrusion die (320) and the lower extrusion die (310). The shaping mold (400) includes an upper shaping mold (420) and a lower shaping mold (410). A T-shaped upper shaping cavity (421) is provided inside the upper shaping mold (420), and a lower shaping cavity (411) is provided inside the lower shaping mold (410). The centers of the upper shaping cavity (421) and the lower shaping cavity (411) are located on the opposite end faces of the upper shaping mold (420) and the lower shaping mold (410). S300. Apply anti-oxidation coating evenly to the inner and outer surfaces of the tube blank and then let it dry. S400. The extrusion die (300) is assembled on the press, the tube blank is placed in the extrusion cavity (311), the tube blank is heated to the preset extrusion temperature, and after the preset time of heat preservation, the press is started, and the extrusion upper die (320) is pressed down radially until the extrusion upper die (320) and the extrusion lower die (310) are in contact, and the tube blank forms the main tube section (110) and the branch tube section (120) connected to the main tube section (110). S500. The main pipe is machined according to the design requirements, and the branch pipe (120) is drawn to the pre-processed size to form a pre-processed tee pipe. S600. The forming mold (400) is assembled on the press. The pre-processed tee pipe is placed in the forming lower cavity (411). The pre-processed tee pipe is heated to the preset extrusion temperature. After the preset time of heat preservation, the press is started and the forming upper mold (420) is pressed down until the forming upper mold (420) and the forming lower mold (410) are fitted together to form a semi-finished tee pipe. S700: Machining of semi-finished tee pipes to meet design requirements; S800, Vacuum heat treatment is performed on the semi-finished tee pipe; S900. Surface treatment is performed on the semi-finished tee pipe to form a finished tee pipe fitting (100).

2. The method for preparing the powder metallurgy titanium alloy T-type tee fitting according to claim 1, characterized in that, In step S100, The tube blank mold is an elliptical sleeve with the length of the major axis a = 1.5D and the length of the minor axis c = D, where D is the outer diameter of the main pipe of the tee fitting.

3. The method for preparing the powder metallurgy titanium alloy T-type tee fitting according to claim 1, characterized in that, In step S100, the vacuum degree after evacuating the tube blank mold is no greater than 10. -2 Pa.

4. The method for preparing the powder metallurgy titanium alloy T-type tee fitting according to claim 1, characterized in that, In step S100, the hot isostatic pressing requirements are: temperature of 900℃~1100℃, pressure of 100MPa~140MPa, and holding time of 2-6h.

5. The method for preparing the powder metallurgy titanium alloy T-type tee fitting according to claim 1, characterized in that, In step S200, the through hole and groove of the upper cavity are connected by a rounded transition, with a transition radius R of 25~35mm.

6. The method for preparing the powder metallurgy titanium alloy T-type tee pipe fitting according to claim 5, characterized in that, In step S400, when the extrusion die (300) is assembled onto the press, the center lines of the upper extrusion die (320) and the lower extrusion die (310) are aligned. In step S600, when the shaping mold (400) is assembled on the press, the center lines of the upper shaping mold (420) and the lower shaping mold (410) are aligned.

7. The method for preparing the powder metallurgy titanium alloy T-type tee pipe fitting according to claim 6, characterized in that, In steps S400 and S600, when the extrusion molding die (300) or shaping die (400) is assembled onto the press, the die is preheated to 200~300°C. The preset extrusion temperature is 800~850℃, and the holding time is 5~10min.

8. The method for preparing the powder metallurgy titanium alloy T-type tee pipe fitting according to claim 1, characterized in that, In steps S400 and S600, the forming process is carried out in at least two steps, and the deformation amount of each step is 20~40%.

9. The method for preparing the powder metallurgy titanium alloy T-type tee fitting according to claim 1, characterized in that, In step S900, the surface treatment method includes: The surface anti-oxidation coating of the tee fitting (100) is removed by sandblasting, and the tee fitting (100) is then ground.

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