A composite manufacturing method of a TC11 titanium alloy thin-wall cylinder

Abstract

A kind of composite manufacturing method of TC11 titanium alloy thin-walled cylinder, based on the idea of additive + welding composite manufacturing, according to the size and structure characteristics of workpiece, the complex shape part in thin-walled cylinder is prepared by selective laser melting, and the other part is prepared by machining of forgings.The additive + welding composite method is used to manufacture TC11 titanium alloy thin-walled cylinder, which solves the problem that the integration forming of large-size aerospace structure is limited by the volume of atmosphere cabin or vacuum chamber, realizes the optimization of processing resources, and takes into account the processing efficiency and material utilization.The addition of Cu and Mn powder promotes the composition of the solid-liquid front of the molten pool to be supercooled, thereby promoting the transformation of columnar crystal to equiaxed crystal, and equiaxed grains are obtained by additive manufacturing.The tensile strength of TC11 alloy after double annealing is 1285MPa, and the elongation is 9.5%.Laser welding method is used to realize the connection of additive manufacturing TC11 alloy and forged TC11 alloy, and the tensile strength of the welded joint is 1536.5MPa, and the fracture mode is plastic fracture.

Description

Technical Field

[0001] This invention relates to the field of precision manufacturing, specifically a composite manufacturing method for large-size TC11 titanium alloy thin-walled cylindrical bodies. Background Technology

[0002] Thin-walled cylinders are key metal components of aerospace engines, bearing severe flight mechanical and thermal loads during engine operation. With the development of aerospace technology, the structure of thin-walled cylinders in aerospace engines is becoming increasingly complex, and materials are evolving from traditional high-strength steel to lightweight, high-strength titanium alloys. The traditional manufacturing process for high-strength steel cylinders in engines is as follows: spinning the cylinder → assembling and welding joints and external components → heat treatment of the entire shell → machining of the entire shell.

[0003] TC11 is an α+β type heat-resistant titanium alloy, known for its high strength, good corrosion resistance, and thermal stability. Compared to high-strength steel cylinders, TC11 titanium alloy cylinders offer superior lightweight advantages. However, TC11 titanium alloy has poor spinnability and machinability, resulting in poor formability of thin-walled cylinders compared to traditional ultra-high-strength steel. This significantly limits the application of titanium alloys in thin-walled cylindrical components for solid rocket motors.

[0004] Selective laser melting (SLM) is a process in which a laser beam rapidly melts metal powder according to CAD drawing data, layer by layer, to form metal parts with various complex shapes and a density approaching 100%. It has unique advantages for processing structurally complex parts, variable cross-sections, and irregularly shaped components, offering a series of benefits such as high forming accuracy and high material utilization.

[0005] In recent years, selective laser melting technology has gradually been applied in the aerospace field. For example, patent 202010738832.9 discloses a process method for laser additive manufacturing of high-strength aluminum alloy structures, which can realize the forming of complex parts such as biomimetic structures and topology-optimized structures, with aluminum alloy strength reaching over 530 MPa. Patent 202011489777.0 discloses a method for additive manufacturing of complex high-strength aluminum alloy structures, which reduces the surface roughness of the formed parts by optimizing the selective laser melting forming process.

[0006] The aforementioned patents all employ selective laser melting (SLM) technology for direct forming. However, current SLM equipment is relatively small, capable of printing heights less than 1600mm, and cannot achieve integrated printing of parts larger than 2000mm. A composite manufacturing technology combining SLM additive manufacturing and welding can achieve the forming of large-sized parts. Furthermore, the microstructure of TC11 titanium alloy parts prepared by SLM is characterized by coarse columnar grains composed of fine martensitic α-phase, which differs significantly from the microstructure of titanium alloy forgings. These coarse columnar grains typically lead to anisotropy in mechanical properties, affecting the service performance of the parts. Summary of the Invention

[0007] To overcome the shortcomings of selective laser melting in constructing TC11 titanium alloy thin-walled cylinders, which suffer from reduced mechanical properties due to coarse columnar grains, this invention proposes a composite manufacturing method for TC11 titanium alloy thin-walled cylinders.

[0008] The specific process of this invention is as follows:

[0009] Step 1: Divide the titanium alloy thin-walled cylinder according to different processes;

[0010] The cylinder is divided into two parts: the first section and the second section.

[0011] The first section of the cylinder is the closed end of the cylinder, and the second section of the cylinder is the open end of the cylinder. The boundary between the first section of the cylinder and the second section of the cylinder is located at the step on the outer circumferential surface of the cylinder. The second section of the cylinder is a section of equal diameter and will be prepared by traditional forging. The first section of the cylinder is a section of complex structure and will be prepared by selective laser melting.

[0012] Step 2, Preparation of alloying powder:

[0013] Cu and Mn powders were added to TC11 titanium alloy powder and mixed evenly; the alloyed powder required for selective laser melting was obtained by ball milling.

[0014] The Cu powder and Mn powder in the alloy powder account for a and b of the TC11 titanium alloy by mass, respectively. a and b should satisfy: a = 0.7% to 2.1%, b = 0.6% to 1.7%, and the sum of a and b should be ≤ 2.7% of the total amount of the TC11 titanium alloy powder.

[0015] The TC11 powder is spherical with a particle size of 15–53 μm. The Cu powder is spherical with a particle size of 0.5–4 μm. The Mn powder is spherical with a particle size of 0.5–4 μm.

[0016] Ball milling was used to ensure that Cu and Mn powders adhered fully to TC11 titanium alloy powder, achieving uniform mixing of powders of different elements. The ball milling speed was 300 r / min; the ball-to-powder ratio was 3:10.

[0017] Step 3, prepare the first section of the titanium alloy thin-walled cylinder:

[0018] The first section of a titanium alloy thin-walled cylindrical body was prepared by selective laser melting.

[0019] The first section of the cylinder was drawn using Magics software. The three-dimensional model was then cut into layers of equal thickness (0.03 mm) along the height direction to obtain the layer-by-layer scanning data of the first section of the cylinder. The layer-by-layer scanning data was then imported into the selective laser melting equipment.

[0020] The process parameters for selective laser melting are set as follows: laser power 300–350 W; scanning speed 500–750 mm / s; scanning interval 0.10 mm; layer thickness 0.03 mm; scanning path is a straight line. The scanning direction θ for each layer... j The difference lies in that the scanning direction of the first layer is parallel to the X-axis of the forming chamber of the laser melting device, and the scanning direction of the subsequent layer is increased clockwise by k° based on the scanning direction of the previous layer, which is θ. j = k × j; j is the number of scanning layers, j = 2, 3, ... Until the set height is reached, the preparation of the first section of the titanium alloy thin-walled cylinder is completed.

[0021] The specific process for preparing the first section of the titanium alloy thin-walled cylindrical body is as follows:

[0022] Scan the first layer:

[0023] The obtained alloyed powder is placed into the forming chamber of the selective laser melting device, and a scraper is used to spread the powder to form the first powder bed with a thickness of 0.03 mm. The laser is started, and the powder bed is scanned according to the layer scanning data. The scanning path is a straight line, and the angle between the scanning direction θ1 and the X-axis of the forming chamber of the selective laser melting device is 0°. The laser melting of the first layer of powder is completed.

[0024] Scan the second layer:

[0025] A second powder bed is formed by spreading powder onto the molten first layer of powder using a scraper; the powder bed thickness is 0.03 mm. The laser is activated and scans the molten powder bed according to the layered scanning data; the scanning path is a straight line, rotated clockwise, with an angle θ2 between it and the X-axis. The scanning direction is increased clockwise by 67° from the first layer's scanning direction, so that the angle θ = 67° between the second layer's scanning direction and the X-axis of the laser melting device's forming chamber. The laser melting of the second layer of powder is then complete.

[0026] Scan the third layer:

[0027] A third powder bed is formed by spreading powder onto the second powder bed using a scraper. The powder thickness is 0.03 mm. The laser is activated and scans the melting powder bed according to the layered scanning data. The scanning path is a straight line, and the scanning direction continues to deflect clockwise, with an angle of θ3 between it and the X-axis. The scanning direction is increased clockwise by 67° from the second layer scanning direction, so that the angle θ = 134° between the second layer scanning direction and the X-axis of the laser melting device's forming chamber. The laser melting of the third layer of powder is then completed.

[0028] Repeat the laser melting process from the second layer of powder to the third layer of powder until the set height is reached.

[0029] Step 4, stress-relief annealing:

[0030] Stress-relieving annealing heat treatment is performed on selected area laser melting components.

[0031] The specific process parameters for the stress-relief annealing are as follows: the heat treatment furnace is heated to 540℃ at a heating rate of 3℃ / min and held for 2 hours; after holding, the furnace is cooled. This completes the stress-relief annealing of the first section of the titanium alloy thin-walled cylinder to eliminate the residual stress in the first section of the cylinder.

[0032] Step 5, laser cleaning:

[0033] The first section of the cylinder, after stress-relief annealing, is laser-cleaned to improve its surface quality.

[0034] The surface laser cleaning parameters are: laser power of 90W, laser frequency of 100kHz, and laser scanning linear speed of 0.9~1.1m / s.

[0035] Step 6, machining of the first section of the cylinder:

[0036] Step 6, machining the first cylinder, involves removing excess material from the first section of the cylinder according to the design dimensions and machining an I-shaped welding bevel at the welding area of ​​the first section of the cylinder.

[0037] Step 7, machining of the second section of the thin-walled cylinder:

[0038] The forgings were machined into the second section of the cylinder 2 according to the design requirements using machining methods.

[0039] Step 8, cleaning the bevel:

[0040] Clean the parts to be welded in the first section of the cylinder 1 and the second section of the cylinder 2.

[0041] Step 9, Assembly:

[0042] The first and second cylindrical sections are assembled together. Under the constraint of supporting fixtures, the cylindrical sections are welded using laser welding. This yields a semi-finished TC11 titanium alloy thin-walled cylindrical section.

[0043] The laser welding system consists of an IPG-8000 fiber laser, an ABB 6-axis robot, and a local inert gas shielding device. The laser wavelength is 1070 nm and the spot diameter is 200 μm. The welding parameters are: laser power of 1100 W, welding speed of 1 m / min, defocusing amount of 0 mm, and shielding atmosphere of 99.999% pure argon.

[0044] Step 10, Heat Treatment:

[0045] The semi-finished TC11 titanium alloy thin-walled cylinder was heat-treated using a conventional double annealing method to obtain the TC11 titanium alloy thin-walled cylinder.

[0046] This completes the process of composite manufacturing of the TC11 titanium alloy thin-walled cylinder.

[0047] During the heat treatment, the furnace temperature is increased to 860–890°C at a rate of 3°C / min and held for 1 hour before being air-cooled to room temperature. After air cooling, the furnace temperature is then increased to 560°C and held for 2 hours before being air-cooled again.

[0048] This invention is based on the concept of additive manufacturing and welding. According to the workpiece size and structural characteristics, and taking into account processing efficiency, material consumption, time and the working cavity size of the selective laser melting equipment, the entire cylinder is divided into two parts. The complex part of the thin-walled cylinder is prepared by selective laser melting, while the other part of the thin-walled cylinder is prepared by forging.

[0049] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0050] 1. This invention uses an additive manufacturing + welding composite method to manufacture TC11 titanium alloy thin-walled cylinders, which solves the problem that the integrated forming of large-size aerospace structural components is limited by the volume of atmosphere chambers or vacuum chambers, and realizes the optimized combination of processing resources, taking into account both processing efficiency and material utilization.

[0051] 2. Based on the elemental composition characteristics of TC11 alloy, this invention adds Cu and Mn powders to TC11 alloy powder through a powder mixing and alloying method. The mass percentages of Cu powder and Mn powder in the alloy powder of the TC11 titanium alloy are a and b, respectively, where a = 0.7%–2.1% and b = 0.6%–1.7%, and the sum of a and b is ≤ 2.7% of the total amount of TC11 titanium alloy powder.

[0052] By adding Cu and Mn powders, the compositional supercooling at the solid-liquid front of the molten pool can be increased, thereby promoting the transformation of columnar crystals to equiaxed crystals. Using this alloy powder for additive manufacturing, equiaxed grains were obtained with an average grain size of approximately 32 μm. This solves the problem that the microstructure obtained from additive manufacturing of ordinary TC11 titanium alloy powder consists of coarse columnar grains with a grain width of 100–200 μm and a grain length reaching the millimeter level. After double annealing, the TC11 alloy exhibits a tensile strength of 1285 MPa and an elongation of 9.5%. Laser welding was used to join additively manufactured TC11 alloy with forged TC11 alloy; the welded joint has a tensile strength of 1536.5 MPa and fractures via ductile fracture. Figure 4 As shown. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of a thin-walled titanium alloy structure and its segmentation; among which... Figure 1 It is a thin-walled cylindrical body made of titanium alloy. Figure 1 b represents the first section of the cylinder. Figure 1 c represents the second section of the cylinder.

[0054] Figure 2 It is the microstructure of the additively formed TC11 cylinder after double annealing.

[0055] Figure 3 This is a cross-sectional topography of the TC11 laser-welded head of the additive TC11+ forging; where: Figure 3 a is a high-resolution photograph, and this... Figure 3 a is divided into three regions: 1, 2, and 3. Figure 3 b is a magnified view of region 1 in 3a, that is, the morphology of the heat-affected zone at one end of the additive part; Figure 3 c is a magnified view of region 2 in 3a, that is, the morphology of the weld center; Figure 3 d is a magnified view of region 3 in 3a, which is the heat-affected zone at the other end of the additive part.

[0056] Figure 4 The tensile fracture morphology of the laser-welded head of the additive TC11 + forging is shown; among which: Figure 4 A is a macroscopic photograph of the tensile fracture surface. Figure 4 a is divided into two regions, 1 and 2. Figure 4 b is Figure 4 High-magnification photograph of the tensile fracture fiber zone in region a; Figure 4 c is Figure 4 High-magnification photograph of the shear lip region of the tensile fracture surface in area 2 of region a.

[0057] Figure 5 This is a flowchart of the present invention. Detailed Implementation

[0058] This embodiment describes a composite manufacturing method for a TC11 titanium alloy thin-walled cylindrical body.

[0059] The specific process of this embodiment is as follows:

[0060] Step 1: Divide the titanium alloy thin-walled cylinder according to different processes;

[0061] Based on additive manufacturing and welding, the cylinder is divided into two parts according to the workpiece size and structural characteristics: a first cylinder section 1 and a second cylinder section 2. The first cylinder section 1 is the closed end of the cylinder, and the second cylinder section is the open end of the cylinder. The boundary between the first and second cylinder sections is located at the step on the outer circumferential surface of the cylinder. The second cylinder section 2 is a uniform diameter section and will be manufactured using traditional forging methods. The first cylinder section, which has a complex structure, will be manufactured using selective laser melting.

[0062] Step 2, Preparation of alloying powder:

[0063] The alloyed powder required for selective laser melting was obtained by ball milling and mixing. Cu and Mn powders were added to TC11 titanium alloy powder and mixed evenly.

[0064] The Cu powder and Mn powder in the alloy powder account for a and b of the TC11 titanium alloy by mass, respectively. a and b should satisfy: a = 0.7% to 2.1%, b = 0.6% to 1.7%, and the sum of a and b should be ≤ 2.7% of the total amount of the TC11 titanium alloy powder.

[0065] The TC11 powder is spherical with a particle size of 15–53 μm. The Cu powder is spherical with a particle size of 0.5–4 μm. The Mn powder is spherical with a particle size of 0.5–4 μm.

[0066] Ball milling was used to ensure that Cu and Mn powders adhered fully to TC11 titanium alloy powder, achieving uniform mixing of powders of different elements. The ball milling speed was 300 r / min; the ball-to-powder ratio was 3:10.

[0067] A uniformly mixed alloyed powder is obtained.

[0068] Table 1. Process parameters for step 2 of each embodiment.

[0069]

[0070] Step 3, prepare the first section of the titanium alloy thin-walled cylinder:

[0071] The first section of the titanium alloy thin-walled cylinder 1 was prepared by selective laser melting.

[0072] The three-dimensional model of the first section of the cylinder 1 was drawn using Magics software. The three-dimensional model was then cut into layers of equal thickness of 0.03mm along the height direction to obtain the layer scanning data of the first section of the cylinder 1. The layer scanning data was then imported into the selective laser melting equipment.

[0073] The process parameters for selective laser melting are set as follows: laser power 300–350 W; scanning speed 500–750 mm / s; scanning interval 0.10 mm; layer thickness 0.03 mm; scanning path is a straight line. The scanning direction θ for each layer... j The difference lies in that the scanning direction of the first layer is parallel to the X-axis of the forming chamber of the laser melting device, and the scanning direction of the subsequent layer is increased clockwise by k° based on the scanning direction of the previous layer, which is θ. j = k×j; j is the number of scan layers, j = 2, 3, ...

[0074] Scan the first layer:

[0075] The obtained alloyed powder is placed into the forming chamber of the selective laser melting device, and a scraper is used to spread the powder to form the first powder bed with a thickness of 0.03 mm. The laser is started, and the powder bed is scanned according to the layer scanning data. The scanning path is a straight line, and the angle between the scanning direction θ1 and the X-axis of the forming chamber of the selective laser melting device is 0°. The laser melting of the first layer of powder is completed.

[0076] Table 2 Process parameters for step 3 of each embodiment

[0077]

[0078] Scan the second layer:

[0079] A second powder bed is formed by spreading powder onto the molten first layer of powder using a scraper; the powder bed thickness is 0.03 mm. The laser is activated and scans the molten powder bed according to the layered scanning data; the scanning path is a straight line, rotated clockwise, with an angle θ2 between it and the X-axis. The scanning direction is increased clockwise by 67° from the first layer's scanning direction, so that the angle θ = 67° between the second layer's scanning direction and the X-axis of the laser melting device's forming chamber. The laser melting of the second layer of powder is then complete.

[0080] Scan the third layer:

[0081] A third powder bed is formed by spreading powder onto the second powder bed using a scraper. The powder thickness is 0.03 mm. The laser is activated and scans the melting powder bed according to the layered scanning data. The scanning path is a straight line, and the scanning direction continues to deflect clockwise, with an angle of θ3 between it and the X-axis. The scanning direction is increased clockwise by 67° from the second layer scanning direction, so that the angle θ = 134° between the second layer scanning direction and the X-axis of the laser melting device's forming chamber. The laser melting of the third layer of powder is then completed.

[0082] The scanning process of laser melting the second layer of powder to laser melting the third layer of powder is repeated until the set height is reached, thus completing the preparation of the first section of the titanium alloy thin-walled cylinder.

[0083] Step 4, stress-relief annealing:

[0084] Under the constraints of the supporting fixture, the selected area laser melting component is subjected to stress-relieving annealing heat treatment using conventional methods.

[0085] The specific process parameters for the stress-relief annealing are as follows: the heat treatment furnace is heated to 540℃ at a heating rate of 3℃ / min and held for 2 hours; after holding, the furnace is cooled. This completes the stress-relief annealing of the first section of the titanium alloy thin-walled cylinder to eliminate the residual stress in the first section of the cylinder 1.

[0086] The supporting fixture is existing technology.

[0087] Table 3. Process parameters for step 4 of each embodiment.

[0088]

[0089] Step 5, laser cleaning:

[0090] The first section of the cylinder, after stress-relief annealing, was subjected to laser cleaning to improve its surface quality. The surface laser cleaning parameters were: laser power of 90W, laser frequency of 100kHz, and laser scanning linear speed of 0.9–1.1m / s.

[0091] Table 4. Process parameters for step 5 of each embodiment.

[0092]

[0093] Step 6, machining of the first section of the cylinder:

[0094] Using machining methods, excess material in the first section of the cylinder is removed according to the design dimensions, and an I-shaped welding bevel is machined at the welding area of ​​the first section of the cylinder. Ready for use.

[0095] Step 7, machining of the second section of the thin-walled cylinder:

[0096] Using conventional machining methods, the forgings were machined into the second section of the cylinder 2 according to the design requirements.

[0097] An I-shaped bevel is machined at the welding location of the second section of the cylinder 2 for welding with the first section of the cylinder 1.

[0098] Step 8, cleaning the bevel:

[0099] The areas to be welded in the first section of cylinder 1 and the second section of cylinder 2 are ground to remove oxide scale, pickled, cleaned, and thoroughly dried. The bevels are then cleaned to prepare for welding.

[0100] Step 9, Assembly:

[0101] The first and second cylindrical sections are assembled together. The sections are then welded using laser welding under the constraint of supporting fixtures.

[0102] The laser welding system consists of an IPG-8000 fiber laser, an ABB 6-axis robot, and a local inert gas shielding device. The laser wavelength is 1070 nm and the spot diameter is 200 μm. The welding parameters are: laser power of 1100 W, welding speed of 1 m / min, defocusing amount of 0 mm, and shielding atmosphere of 99.999% pure argon.

[0103] A semi-finished product of TC11 titanium alloy thin-walled cylinder was obtained.

[0104] Step 10, Heat Treatment:

[0105] The obtained semi-finished TC11 titanium alloy thin-walled cylinder is subjected to heat treatment.

[0106] The heat treatment is performed using a conventional double annealing method.

[0107] After welding, the cylinder body undergoes a double annealing heat treatment. The specific process parameters for the double annealing are as follows: the temperature is increased to 860-890℃ in the furnace at a heating rate of 3℃ / min and held for 1 hour, followed by air cooling to room temperature. After air cooling, the temperature is then increased to 560℃ in the furnace and held for 2 hours, followed by air cooling. This yields a TC11 titanium alloy thin-walled cylinder body.

[0108] This completes the process of composite manufacturing of the TC11 titanium alloy thin-walled cylinder.

[0109] Table 5. Process parameters for step 10 of each embodiment.

[0110]

[0111]

Claims

1. A composite manufacturing method for a TC11 titanium alloy thin-walled cylindrical body, characterized in that, The specific process is as follows: Step 1: Divide the titanium alloy thin-walled cylinder according to different processes; The cylinder is divided into two parts: the first section (1) and the second section (2). Step 2, Preparation of alloying powder: Cu and Mn powders were added to TC11 titanium alloy powder and mixed evenly; the alloyed powder required for selective laser melting was obtained by ball milling. In the alloying powder, the mass percentages of Cu powder and Mn powder in the TC11 titanium alloy are a and b, respectively. a and b should satisfy: a = 0.7%~2.1%, b = 0.6%~1.7%, and the sum of a and b ≤ 2.7% of the total amount of the TC11 titanium alloy powder. Step 3, prepare the first section of the titanium alloy thin-walled cylinder: The first section of a titanium alloy thin-walled cylindrical body was prepared by selective laser melting (1). The first section of the cylinder was drawn using Magics software. The three-dimensional model was then cut into layers of equal thickness (0.03 mm) along the height direction to obtain the layer-by-layer scanning data of the first section of the cylinder. The layer-by-layer scanning data was then imported into the selective laser melting device. The process parameters for selective laser melting are set as follows: laser power 300–350 W; scanning speed 500–750 mm / s; scanning interval 0.10 mm; layer thickness 0.03 mm; scanning path straight line; scanning direction θ for each layer. j The difference lies in that the scanning direction of the first layer is parallel to the X-axis of the forming chamber of the selective laser melting device, and the scanning direction of the subsequent layer is increased clockwise by k degrees, denoted as θ, based on the scanning direction of the previous layer. j =k×j; j is the number of scanning layers, j=2,3,…; until the set height is reached, the preparation of the first section of the titanium alloy thin-walled cylinder is completed; Step 4, stress-relief annealing: Stress-relieving annealing heat treatment is performed on selected area laser melting components; Step 5, laser cleaning: The first section of the cylinder, after stress-relief annealing, is subjected to laser cleaning to improve its surface quality. Step 6, machining of the first section of the cylinder; Step 7, machining of the second section of the thin-walled cylinder: The forging was machined into the second section of the cylinder according to the design requirements using machining methods (2); Step 8, cleaning the bevel: Clean the welding parts of the first section of the cylinder (1) and the welding parts of the second section of the cylinder; Step 9, Assembly: The first section of the cylinder is assembled with the second section of the cylinder; the cylinder is welded by laser welding under the constraint of the supporting fixture; a semi-finished product of TC11 titanium alloy thin-walled cylinder is obtained; Step 10, Heat Treatment: The semi-finished TC11 titanium alloy thin-walled cylinder was heat-treated using a double annealing method to obtain the TC11 titanium alloy thin-walled cylinder. This completes the process of composite manufacturing of the TC11 titanium alloy thin-walled cylinder.

2. The composite manufacturing method of a TC11 titanium alloy thin-walled cylindrical body as described in claim 1, characterized in that, The first section of the cylinder (1) is the closed end of the cylinder, and the second section of the cylinder is the open end of the cylinder. The boundary between the first section of the cylinder and the second section of the cylinder is located at the step on the outer circumferential surface of the cylinder, so that the second section of the cylinder (2) is a cylinder section of equal diameter, which will be prepared by traditional forging method, and the first section of the cylinder is a cylinder section with a complex structure, which will be prepared by selective laser melting method.

3. The composite manufacturing method of a TC11 titanium alloy thin-walled cylindrical body as described in claim 1, characterized in that, The TC11 titanium alloy powder is spherical with a particle size of 15–53 μm; the Cu powder is spherical with a particle size of 0.5–4 μm; and the Mn powder is spherical with a particle size of 0.5–4 μm.

4. The composite manufacturing method of a TC11 titanium alloy thin-walled cylindrical body as described in claim 3, characterized in that, Ball milling was used to ensure that Cu and Mn powders were fully adhered to TC11 titanium alloy powder, achieving uniform mixing of powders of different elements; the ball milling speed was 300 r / min; and the ball-to-material ratio was 3:

10.

5. The composite manufacturing method of a TC11 titanium alloy thin-walled cylindrical body as described in claim 1, characterized in that, The specific process for preparing the first section of the titanium alloy thin-walled cylindrical body is as follows: Scan the first layer: The obtained alloyed powder is placed into the forming chamber of the selective laser melting device, and the powder is spread by a scraper to form the first powder bed with a thickness of 0.03 mm. The laser is started, and the powder bed is scanned and melted according to the layer scanning data. The scanning path is a straight line, and the angle between the scanning direction θ1 and the X-axis of the forming chamber of the selective laser melting device is 0°. The laser melting of the first layer of powder is completed. Scan the second layer: A second powder bed is formed by spreading powder on the molten first layer of powder using a scraper; the powder bed thickness is 0.03 mm; the laser is activated, and the molten powder bed is scanned according to the layer scanning data; the scanning path is a straight line, the direction is deflected clockwise, and the angle between the scanning path and the X-axis is θ2. The scanning direction is increased clockwise by 67° based on the scanning direction of the first layer, so that the angle θ2 = 67° between the scanning direction of the second layer and the X-axis of the forming chamber of the selective laser melting device is completed; the laser melting of the second layer of powder is completed. Scan the third layer: A third powder bed is formed by spreading powder on the second powder bed using a scraper; the powder thickness is 0.03 mm; the laser is activated, and the powder bed is scanned and melted according to the layer scanning data; the scanning path is a straight line, and the scanning direction continues to deflect clockwise, with an angle of θ3 between it and the X-axis. The scanning direction is increased by 67° clockwise based on the scanning direction of the second layer, so that the angle θ3 between the scanning direction of the second layer and the X-axis of the forming chamber of the selective laser melting device is 134°; the laser melting of the third powder layer is completed. Repeat the laser melting process from the second layer of powder to the third layer of powder until the set height is reached.

6. The composite manufacturing method of a TC11 titanium alloy thin-walled cylindrical body as described in claim 1, characterized in that, The specific process parameters for stress-relief annealing are as follows: the heat treatment furnace is heated to 540℃ and held for 2 hours at a heating rate of 3℃ / min; after the holding period, the furnace is cooled; stress-relief annealing of the first section of the titanium alloy thin-walled cylinder is completed to eliminate the residual stress of the first section of the cylinder (1).

7. The composite manufacturing method of a TC11 titanium alloy thin-walled cylindrical body as described in claim 1, characterized in that, The surface laser cleaning parameters are: laser power of 90W, laser frequency of 100kHz, and laser scanning linear speed of 0.9~1.1m / s.

8. The composite manufacturing method of a TC11 titanium alloy thin-walled cylindrical body as described in claim 1, characterized in that, Step 6, machining the first cylinder, involves removing excess material from the first section of the cylinder according to the design dimensions and machining an I-shaped welding bevel at the welding area of ​​the first section of the cylinder.

9. The composite manufacturing method of a TC11 titanium alloy thin-walled cylindrical body as described in claim 1, characterized in that, The laser welding system consists of an IPG-8000 fiber laser, an ABB 6-axis robot, and a local inert gas protection device. The laser wavelength is 1070nm and the spot diameter is 200μm. The welding parameters are: laser power of 1100W, welding speed of 1m / min, defocusing amount of 0mm, and protective atmosphere of 99.999% pure argon.

10. The composite manufacturing method of a TC11 titanium alloy thin-walled cylindrical body as described in claim 1, characterized in that, When heat-treating the semi-finished TC11 titanium alloy thin-walled cylinder, the temperature is raised to 860~890℃ in the furnace at a heating rate of 3℃ / min and held for 1 hour before being air-cooled to room temperature; after air-cooling, the temperature is raised to 560℃ in the furnace and held for 2 hours before being air-cooled.

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