High-strength titanium alloy flux-cored wire for additive manufacturing and preparation method and application thereof

Abstract

This invention discloses a high-strength titanium alloy flux-cored welding wire for additive manufacturing. The flux-cored powder is composed of the following components by mass percentage: 4.5%~5.0% aluminum powder, 2.8%~3.2% vanadium powder, 5.3%~5.8% molybdenum powder, 1.5%~1.7% iron powder, 1.4%~1.6% chromium powder, 1%~3% titanium boride powder, with the balance being titanium powder and unavoidable impurities. The preparation method includes: 1. Preparing the flux-cored powder, filling it, and then rolling and drawing it; 2. Roll drawing and vacuum annealing; 3. Continuous rolling and polishing. This flux-cored welding wire is then used in additive manufacturing. This invention utilizes EDEM software to calculate the flowability and the ratio of coarse to fine powder, achieving homogenization and low impurity content in the flux-cored powder. When used in additive manufacturing, this flux-cored welding wire avoids element loss and agglomeration, resulting in titanium alloy products with uniform composition and microstructure. Furthermore, it offers high manufacturing freedom, high production efficiency, and high yield, making it suitable for the additive manufacturing field.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to a high-strength titanium alloy flux-cored welding wire for additive manufacturing, its preparation method, and its application. Background Technology

[0002] Titanium alloys possess a range of advantages, including low density, high strength, excellent corrosion resistance, and superior high-temperature performance, leading to their widespread application in aerospace, shipbuilding, and chemical industries. Additive manufacturing technology provides a new approach for near-net-shape forming of titanium alloy components. Titanium alloy flux-cored welding wire, as a crucial raw material in additive manufacturing, plays a key role in the quality and performance of additively manufactured parts. Currently, the preparation of solid titanium alloy welding wire for additive manufacturing faces the following challenges: a single alloy composition and difficulty in incorporating reinforcing phases; poor molten pool fluidity leading to defects such as porosity and cracks; uneven melting of the titanium alloy welding wire during additive manufacturing, requiring strict control of printing parameters and affecting forming quality; conventional welding wire preparation requires multiple rolling and annealing passes, resulting in high cost and low efficiency; and existing welding wire compositions and microstructures are insufficient to meet the requirements of arc additive manufacturing for interlayer bonding strength and forming accuracy.

[0003] The aforementioned issues have, to some extent, limited the further application of titanium alloy flux-cored welding wire in additive manufacturing. To meet the ever-increasing demands of high-end manufacturing for the comprehensive performance of titanium alloys, developing a high-strength titanium alloy welding wire with reinforcing phases, low porosity, and stability during the additive manufacturing process is of great significance.

[0004] Patent publication number CN118976796A discloses a method for preparing Ti6Al4V alloy powder-core wire. This method utilizes CP-Ti tape to coat metal powder and a binder, followed by rolling to gradually reduce the thickness of the powder core wire. Results show that the blocks printed using Ti6Al4V alloy wire with a diameter of 2mm exhibit good strength and plasticity. However, the addition of the binder is overly cumbersome, and the vacuum mixing temperature is too low to effectively relieve stress. Furthermore, printing with a 2mm diameter titanium alloy wire places extremely high demands on arc-fused wire equipment, which cannot meet the requirements of commercially available equipment.

[0005] Patent publication number CN114043121A discloses a titanium-aluminum powder-cored welding wire and its preparation method. The method involves coating powder with a U-shaped metal outer sheath, joining the ends, and then processing with a wire drawing machine to produce a titanium-aluminum alloy wire suitable for additive manufacturing. However, the vacuum heat treatment temperature in this process is only 80℃~90℃, which is insufficient to achieve stress relief. Furthermore, patent publication number CN120133794A discloses a high-strength titanium alloy flux-cored welding wire and its preparation method. By optimizing the alloy composition and flux formulation, and improving the preparation process, a flux-cored welding wire with good comprehensive performance is obtained. The results show that this titanium alloy flux-cored welding wire can improve the fluidity of the weld pool, enhance the stability of the welding arc, and control the weld microstructure during application. However, the titanium alloy strength produced by the flux-cored welding wires from these two patents using additive manufacturing technology does not meet the requirements for high-strength wires.

[0006] Patent publication number CN112404798A discloses a method for preparing TC4 titanium alloy flux-cored welding wire. This method is simple and easy to implement. It utilizes TA1 titanium strip to wrap ball-milled powder (vanadium powder: 16%, aluminum powder: 25%, molybdenum powder: 15%, cobalt powder: 0.3%, nickel powder: 4%, copper powder: 1.0%, silicon powder: 0.3%, the remainder being titanium powder); fills the powder with flux, rolls to reduce the diameter, anneals, and then cold-draws it to obtain a flux-cored welding wire with a diameter of 1.2 mm. Results show that this flux-cored welding wire improves deposition efficiency in the welding field, reduces spatter during welding, and produces good weld formation, demonstrating good application prospects. However, the titanium alloy flux-cored welding wire prepared using this method has poor compositional uniformity and a low yield. Summary of the Invention

[0007] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a high-strength titanium alloy flux-cored welding wire for additive manufacturing. This titanium alloy flux-cored welding wire incorporates titanium boride reinforcing phases into the flux-cored powder and uses EDEM software to calculate powder flowability and the ratio of coarse to fine powder, resulting in homogeneous flux-cored powder with low impurity content. When used as a raw material for additive manufacturing, it effectively avoids element loss and segregation, enabling control over the microstructure and properties of the titanium alloy. This facilitates the production of titanium alloy products with uniform composition and microstructure, solving the problem that the high compositional uniformity and impurity content of existing additive manufacturing titanium alloys fail to meet the stringent requirements of high-end manufacturing industries.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a high-strength titanium alloy flux-cored welding wire for additive manufacturing, characterized in that the flux-cored powder in the titanium alloy flux-cored welding wire is composed of the following components in mass percentage: aluminum powder 4.5%~5.0%, vanadium powder 2.8%~3.2%, molybdenum powder 5.3%~5.8%, iron powder 1.5%~1.7%, chromium powder 1.4%~1.6%, titanium boride powder 1%~3%, and the balance being titanium powder and unavoidable impurities.

[0009] The above-mentioned high-strength titanium alloy flux-cored welding wire for additive manufacturing is characterized in that the mass ratio of coarse powder to fine powder in the flux-cored powder is 4~5:1, wherein the coarse powder is titanium powder with a particle size of 53μm~150μm, the remaining powder is fine powder with a particle size of 15μm~53μm, and the average particle size of the flux-cored powder is 15μm~150μm.

[0010] The above-mentioned high-strength titanium alloy flux-cored welding wire for additive manufacturing is characterized in that the mass percentage of each element in the unavoidable impurities is: C≤0.10%, N≤0.03%, H≤0.015%, O≤0.10%.

[0011] The above-mentioned high-strength titanium alloy flux-cored welding wire for additive manufacturing is characterized in that the outer sheath of the titanium alloy flux-cored welding wire is TA1 titanium strip with a width of 8mm~10mm and a thickness of 0.3mm~0.5mm.

[0012] Meanwhile, this invention also discloses a method for preparing the high-strength titanium alloy flux-cored welding wire for additive manufacturing as described above, characterized in that the method includes the following steps:

[0013] Step 1: Material Filling: Using EDEM software, preset the target composition of the core powder. Create a powder model with coarse titanium powder (53μm~150μm) and fine powder (15μm~53μm). Then, calculate the flowability of the core powder based on its velocity into the outer casing. Select the Hertz-Mundell-Fleming contact model, designing physical parameters such as Poisson's ratio of 0.28~0.3, static friction coefficient of 0.35~0.5, rolling friction coefficient of 0.01, and setting the acceleration to 1.67m / s². 2 This ensures that the error of iterative calibration is less than 5%. Then, based on the simulation scenario output results, the average particle size of the core powder and the mass ratio of coarse powder to fine powder are determined, and the core powder is prepared.

[0014] The outer sheath of the titanium alloy flux-cored welding wire is rolled into a U-shaped groove on a rolling and drawing machine, and flux powder is filled into the U-shaped groove to obtain a blank flux-cored welding wire. The blank flux-cored welding wire is rolled and drawn to obtain the original welding wire.

[0015] Step 2, Roller drawing and annealing: The original welding wire from Step 1 is rolled and drawn to gradually reduce its diameter, with a deformation of 50% to 60%. Then, surface cleaning and vacuum annealing are performed to eliminate work hardening, resulting in intermediate welding wire.

[0016] Step 3: Roller drawing: The intermediate welding wire obtained in Step 2 is continuously drawn through a roller die to gradually reduce its diameter, with a deformation of 15%~20%. After surface polishing, a high-strength titanium alloy flux-cored welding wire is obtained.

[0017] This invention employs a process involving coating the core powder with an outer sheath, followed by roller drawing and vacuum annealing to obtain the flux-cored welding wire. By utilizing EDEM software to calculate the core powder and determine the mass ratio of coarse to fine powder and the average particle size of the core powder, fine powder particles are ensured to fully fill the gaps between coarse powder particles, forming a dense structure with low porosity. This structure reduces the free space within the core powder system, restricts the relative displacement of particles, inhibits particle size segregation, balances interparticle forces, achieves close packing, and reduces porosity and specific surface area, thus achieving high homogeneity. Simultaneously, the uniform distribution of the core powder composition ensures consistent heat conduction during arc heating, preventing excessive localized overheating that could lead to excessive burn-off or abnormal reactions of certain components (such as easily oxidized elements), resulting in a stable and controllable welding metallurgical reaction and reduced impurity generation. Furthermore, the uniform core powder distribution facilitates the efficient removal of impurities from the molten pool, resulting in a lower impurity content. In summary, this invention, through its material filling design, effectively avoids metallurgical problems such as element burn-off and segregation in titanium alloy flux-cored welding wire during additive manufacturing, and meets the requirements for adding easily burnable and refractory metal components to titanium alloy welding wire, making it suitable for additive manufacturing requirements.

[0018] This invention, through strict control of each step in the preparation process, reduces impurities in the manufacturing process and raw materials, ensuring high purity of the welding wire during the roller drawing and diameter reduction process. This results in a low-impurity titanium alloy flux-cored welding wire, providing a smooth and clean wire material for additive manufacturing. It also ensures uniform element distribution during additive manufacturing and eliminates infusibility, thereby guaranteeing the quality of downstream titanium alloy products, improving yield, and significantly reducing production costs. Furthermore, the preparation method of this invention facilitates the control of the titanium alloy flux-cored welding wire's composition and can be extended to the production of other metallic materials.

[0019] The above preparation method is characterized in that the average particle size of the core powder determined in step one is 15μm~150μm, and the preparation method of the core powder is as follows: aluminum powder, vanadium powder, molybdenum powder, iron powder, chromium powder, titanium powder and titanium boride powder are placed in a vacuum drying oven and dried at 100℃~140℃ and a vacuum degree of 10. -3 Pa~10 -2The powder is dried under Pa conditions for 1.5 to 2.5 hours, then vacuum-milled using a planetary ball mill with zirconium balls as the milling medium at a ball-to-material ratio of 15:1, a rotation speed of 150 to 250 rpm, and a milling time of 1.5 to 2.5 hours. After milling, the powder is sieved and stored in an argon atmosphere. The filling rate of the flux-cored wire in the U-shaped groove is 30% to 50%. This invention, by strictly controlling the particle size ratio of the powder raw materials, ensures a moderate degree of reaction of the flux-cored wire during additive manufacturing, avoiding excessively vigorous reactions that could lead to severe sputtering and contamination of the chamber, while also avoiding excessively mild reactions that could result in poor alloy uniformity. This improves the quality and yield of titanium alloy products and reduces the impurity content in the titanium alloy products.

[0020] The above preparation method is characterized in that the vacuum degree of the vacuum annealing in step two does not exceed 5 × 10⁻⁶. -3 The vacuum annealing process, with a temperature of 550℃~650℃ and a holding time of 1.0h~2.0h, effectively eliminates most of the air (especially oxygen) during the annealing process, providing an inert environment with low oxygen partial pressure. This fundamentally prevents new oxidation of the welding wire surface and flux core at high temperatures, a prerequisite for ensuring "low impurity content." Furthermore, the welding wire surface is typically cleaned before and after vacuum annealing to remove adhering materials, and dried to remove moisture and other impurities stored inside and outside the wire. This avoids severe reaction sputtering during subsequent arc additive manufacturing processes.

[0021] The above-described preparation method is characterized in that, in step one, the diameter of the initial flux-cored welding wire is 3.3mm~3.4mm, and the diameter of the original welding wire is 3.0mm~3.1mm; in step two, the diameter of the intermediate welding wire is 2.0mm~2.1mm; and in step three, the diameter of the high-strength titanium alloy flux-cored welding wire is 1.2mm~1.6mm. The high-strength titanium alloy flux-cored welding wire prepared by this invention meets the requirements for arc-fused-wire additive manufacturing equipment in the market and has strong scalability.

[0022] In addition, the present invention also discloses an application of the high-strength titanium alloy flux-cored welding wire for additive manufacturing as described above. The high-strength titanium alloy flux-cored welding wire is surface-treated and then loaded into an arc wire additive manufacturing equipment. The working parameters are adjusted and inert gas is introduced for protection to carry out additive manufacturing and obtain titanium alloy products.

[0023] The above application is characterized by the following additive manufacturing process parameters: peak current 140A~180A, base current 90A~100A, arc voltage 16V~26V, wire feed speed 0.5m / min~1.2m / min, interlayer interval time 60s~70s, lift 1.8mm~2.0mm, and interlayer temperature not exceeding 150℃. These process parameters achieve more stable droplet transition and precise line energy control, avoiding droplet explosion or large particle splashing caused by excessive current impact. While ensuring melt depth, they minimize thermal shock to the solidified layer, facilitating interlayer temperature control.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The titanium alloy flux-cored welding wire of the present invention incorporates titanium boride reinforcing phase into the flux-cored powder and uses EDEM software to calculate the flowability and coarse-fine powder ratio, resulting in flux-cored powder with high homogeneity and low impurity content. Therefore, when using the titanium alloy flux-cored welding wire as a raw material for additive manufacturing, it effectively avoids the burn-off of low-melting-point elements and the segregation of low-density high-melting-point elements to form refractory phases, improves the flowability of the titanium alloy molten pool, enhances the arc stability of additive manufacturing, and enables the control of the microstructure and properties of the titanium alloy. This is beneficial for obtaining titanium alloy products with uniform composition and microstructure, minimizing segregation, and ensuring the service performance of the titanium alloy products.

[0026] 2. The titanium alloy flux-cored welding wire of the present invention uses EDEM software to calculate and control the composition and particle size of the flux-cored powder. This not only obtains uniformly mixed flux-cored powder and ensures the smooth preparation of subsequent flux-cored welding wires, but also improves the fluidity of the additive manufacturing molten reaction products, allowing the powder melt to fully contact, accelerating gas discharge, avoiding contamination of the molten reaction products, improving the yield of additive manufacturing, enhancing the quality of titanium alloy products, avoiding material waste, and reducing production costs.

[0027] 3. The titanium alloy flux-cored welding wire of this invention breaks through the traditional design concept of flux-cored welding wire, and obtains a flux-cored welding wire with excellent comprehensive performance. Furthermore, by combining the control of additive manufacturing process parameters, it improves the fluidity of the molten pool, enhances the arc stability of additive manufacturing, realizes the additive manufacturing of high-quality complex titanium alloy products, and improves the strength and toughness of titanium alloy products. It can meet the strict requirements of high-end manufacturing industry for the performance of titanium alloy materials and is suitable for rapid prototyping and repair of complex structural parts in industrial fields such as vehicles, ships and aerospace.

[0028] 4. The titanium alloy flux-cored welding wire of the present invention has a high degree of design freedom and a simple and effective preparation method. It is easy to achieve personalized customization, suitable for large-scale industrial production, and suitable for promotion to the preparation of high-entropy alloys, including refractory metal materials.

[0029] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0030] Figure 1 This is a simulation diagram of the flowability of the core powder calculated using EDEM software in Example 1 of the present invention.

[0031] Figure 2 This is a physical image of the titanium alloy flux-cored welding wire prepared in Example 1 of the present invention.

[0032] Figure 3 This is a physical image of the titanium alloy block prepared by arc welding wire additive manufacturing of the titanium alloy flux-cored welding wire of Embodiment 1 of the present invention. Detailed Implementation

[0033] Example 1

[0034] The high-strength titanium alloy flux-cored wire for additive manufacturing in this embodiment includes a metal TA1 sheath and flux powder encased within the metal TA1 sheath. The flux powder is composed of the following components by mass percentage: 5.0% aluminum powder, 3.1% vanadium powder, 5.5% molybdenum powder, 1.6% iron powder, 1.6% chromium powder, 2% titanium boride powder, with the balance being titanium powder and unavoidable impurities. The mass percentage of each element in the unavoidable impurities is: C≤0.10%, N≤0.03%, H≤0.015%, O≤0.10%.

[0035] The preparation method of the high-strength titanium alloy flux-cored welding wire for additive manufacturing in this embodiment includes the following steps:

[0036] Step 1: Material Filling: Using EDEM software, preset the target composition of the core powder. Create a powder model where the coarse powder (titanium powder) has a particle size of 53μm~150μm, and the remaining powder (fine powder) has a particle size of 15μm~53μm. Then, based on the core powder entering the outer TA1 titanium belt at a speed of 0.8m / s, calculate the flowability of the core powder. Select the Hertz-Mundell-Fleming contact model, design the physical parameters as Poisson's ratio 0.3, static friction coefficient 0.5, rolling friction coefficient 0.01, and set the acceleration to 1.67m / s². 2 This ensures that the error of the iterative calibration is less than 5%. The density of the core powder, the particle size of the coarse and fine powders, Poisson's ratio, static friction coefficient, and rolling friction coefficient are input sequentially. Then, parameters such as acceleration and relative contact are set to simulate the flow velocity of the core powder and output the results. The simulation graph is shown below. Figure 1 As shown, the two figures above are schematic diagrams simulating the flow rate of the core powder, and the figure below reveals the relationship between the cumulative mass of the core powder and time. The average particle size of the core powder is determined to be 53 μm, and the mass ratio of coarse powder to fine powder is approximately 4:1.

[0037] Then, aluminum powder, vanadium powder, molybdenum powder, iron powder, chromium powder, titanium powder, and titanium boride powder were placed in a vacuum drying oven at 100°C and a vacuum degree of 10. -3 ~10 -2 The powder was dried in an argon atmosphere for 1.5 hours. The dried powder was then vacuum-milled using a planetary ball mill with zirconium balls as the milling medium, a ball-to-material ratio of 15:1, a rotation speed of 150 r / min, and a milling time of 1.5 hours. The powder was then sieved through an 80-120 mesh screen to obtain the core powder, which was stored in an argon atmosphere.

[0038] A TA1 titanium strip with a width of 8 mm and a thickness of 0.3 mm is rolled into a U-shaped groove on a roller die, and flux-cored powder is filled into the U-shaped groove to obtain a blank flux-cored welding wire with a diameter of 3.3 mm to 3.4 mm and a filling rate of 50%. The blank flux-cored welding wire is rolled and drawn to obtain a raw welding wire with a diameter of 3.0 mm to 3.1 mm.

[0039] Step 2, Roller Drawing and Annealing: The original welding wire from Step 1 is subjected to six sets of roller drawing for progressive diameter reduction. The deformation during roller drawing is 50%. Then, vacuum annealing is performed to eliminate work hardening, with a vacuum degree not exceeding 5 × 10⁻⁶. -3 Pa, temperature 550℃, holding time 1.0h, to obtain intermediate welding wire with a diameter of 2.0mm~2.1mm;

[0040] Step 3: Roller drawing: The intermediate welding wire obtained in Step 2 is continuously drawn using four sets of roller dies to gradually reduce its diameter. After surface polishing, a high-strength titanium alloy flux-cored welding wire with a diameter of 1.6 mm is obtained. Figure 2 As shown.

[0041] The application of the high-strength titanium alloy flux-cored welding wire for additive manufacturing in this embodiment is as follows: After surface treatment, the high-strength titanium alloy flux-cored welding wire is loaded into an arc-fused-wire additive manufacturing equipment. The operating parameters are adjusted and argon gas is introduced for protection. Additive manufacturing is then performed with a peak current of 180A, a base current of 100A, an arc voltage of 26V, a wire feed speed of 1.2m / min, an interpass interval of 70s, a lift of 2.0mm, and an interpass temperature not exceeding 150℃, resulting in a titanium alloy block. Figure 3 As shown.

[0042] The mechanical properties and elemental content of the titanium alloy bulk material (deposited state) produced by the titanium alloy flux-cored welding wire additive manufacturing in this embodiment were tested, and the results are shown in Table 1 and Table 2 below.

[0043] Table 1

[0044]

[0045] As shown in Table 1, the high-strength titanium alloy flux-cored wire prepared in this embodiment produces titanium alloy products with high strength through additive manufacturing, and thus belongs to the category of high-strength titanium alloy flux-cored wire.

[0046] Table 2

[0047]

[0048] As shown in Table 2, the high-strength titanium alloy flux-cored welding wire prepared in this embodiment produces titanium alloy products with uniform distribution of major elements, especially with low oxygen content, which effectively avoids the brittleness of titanium alloy materials.

[0049] Example 2

[0050] The high-strength titanium alloy flux-cored wire for additive manufacturing in this embodiment includes a metal TA1 sheath and flux powder encased within the metal TA1 sheath. The flux powder is composed of the following components by mass percentage: 4.9% aluminum powder, 3.0% vanadium powder, 5.6% molybdenum powder, 1.65% iron powder, 1.55% chromium powder, 1% titanium boride powder, with the balance being titanium powder and unavoidable impurities. The mass percentage of each element in the unavoidable impurities is: C≤0.10%, N≤0.03%, H≤0.015%, O≤0.10%.

[0051] The preparation method of the high-strength titanium alloy flux-cored welding wire for additive manufacturing in this embodiment includes the following steps:

[0052] Step 1: Material Filling: Using EDEM software, preset the target composition of the core powder. Create a powder model where the coarse powder (titanium powder) has a particle size of 53μm~150μm, and the remaining powder (fine powder) has a particle size of 15μm~53μm. Then, based on the core powder entering the outer TA1 titanium belt at a speed of 0.8m / s, calculate the flowability of the core powder. Select the Hertz-Mundell-Fleming contact model, design the physical parameters as Poisson's ratio of 0.29, static friction coefficient of 0.45, rolling friction coefficient of 0.01, and set the acceleration to 1.67m / s². 2 This ensures that the error of iterative calibration is less than 5%. The density of the core powder, the particle size of the coarse and fine powders, Poisson's ratio, static friction coefficient and rolling friction coefficient are input sequentially. Then, parameters such as acceleration and relative contact are set to simulate the flow rate of the core powder and output the results. The average particle size of the core powder is determined to be 83 μm, and the mass ratio of coarse to fine powder is approximately 4.5:1.

[0053] Then, aluminum powder, vanadium powder, molybdenum powder, iron powder, chromium powder, titanium powder, and titanium boride powder were placed in a vacuum drying oven at 120°C and a vacuum degree of 10. -3 ~10 -2 The powder was dried under Pa for 2.0 h, and then vacuum ball milled and mixed using a planetary ball mill with zirconium balls as the milling medium, a ball-to-material ratio of 15:1, a rotation speed of 200 r / min, and a milling time of 2.0 h. The powder was then sieved through an 80-120 mesh sieve to obtain the core powder, which was stored in an argon atmosphere.

[0054] A TA1 titanium strip with a width of 9 mm and a thickness of 0.4 mm is rolled into a U-shaped groove on a roller die, and flux-cored powder is filled into the U-shaped groove to obtain a blank flux-cored welding wire with a diameter of 3.3 mm to 3.4 mm and a filling rate of 40%. The blank flux-cored welding wire is rolled and drawn to obtain a raw welding wire with a diameter of 3.0 mm to 3.1 mm.

[0055] Step 2, Roller Drawing and Annealing: The original welding wire from Step 1 is subjected to six sets of roller drawing for progressive diameter reduction. The deformation during roller drawing is 55%. Then, vacuum annealing is performed to eliminate work hardening, with a vacuum degree not exceeding 5 × 10⁻⁶. -3 Pa, temperature 600℃, holding time 1.5h, to obtain intermediate welding wire with a diameter of 2.0mm~2.1mm;

[0056] Step 3: Roller drawing: The intermediate welding wire obtained in Step 2 is continuously drawn through four sets of roller dies to gradually reduce its diameter. After surface polishing, a high-strength titanium alloy flux-cored welding wire with a diameter of 1.4 mm is obtained.

[0057] The application of the high-strength titanium alloy flux-cored welding wire for additive manufacturing in this embodiment is as follows: After surface treatment, the high-strength titanium alloy flux-cored welding wire is loaded into the arc wire additive manufacturing equipment. The working parameters are adjusted and argon gas is filled for protection. Then, additive manufacturing is carried out with a peak current of 160A, a base current of 95A, an arc voltage of 20V, a wire feed speed of 1.0m / min, an interpass interval of 65s, a lift of 1.9mm, and an interpass temperature not exceeding 150℃ to obtain a titanium alloy block.

[0058] The mechanical properties and elemental content of the titanium alloy bulk material (deposited state) produced by the titanium alloy flux-cored welding wire additive manufacturing in this embodiment were tested, and the results are shown in Tables 3 and 4 below.

[0059] Table 3

[0060]

[0061] As shown in Table 3, the high-strength titanium alloy flux-cored wire prepared in this embodiment produces titanium alloy products with high strength through additive manufacturing, and thus belongs to the category of high-strength titanium alloy flux-cored wire.

[0062] Table 4

[0063]

[0064] As shown in Table 4, the titanium alloy products obtained by additive manufacturing of the high-strength titanium alloy flux-cored wire prepared in this embodiment have a uniform distribution of major elements, especially the oxygen content which is close to 0.1%. Due to the strong solid solution strengthening effect of oxygen, the strength of the β phase of the titanium alloy is greatly improved, thereby changing the strength matching relationship between the α phase and the β phase, and slightly improving its plasticity.

[0065] Example 3

[0066] The high-strength titanium alloy flux-cored wire for additive manufacturing in this embodiment includes a metal TA1 sheath and flux powder encased within the metal TA1 sheath. The flux powder is composed of the following components by mass percentage: 5.0% aluminum powder, 3.2% vanadium powder, 5.8% molybdenum powder, 1.7% iron powder, 1.6% chromium powder, 3% titanium boride powder, with the balance being titanium powder and unavoidable impurities. The mass percentage of each element in the unavoidable impurities is: C≤0.10%, N≤0.03%, H≤0.015%, O≤0.10%.

[0067] The preparation method of the high-strength titanium alloy flux-cored welding wire for additive manufacturing in this embodiment includes the following steps:

[0068] Step 1: Material Filling: Using EDEM software, preset the target composition of the core powder. Create a powder model where the coarse powder (titanium powder) has a particle size of 53μm~150μm, and the remaining powder (fine powder) has a particle size of 15μm~53μm. Then, based on the core powder entering the outer TA1 titanium belt at a speed of 0.8m / s, calculate the flowability of the core powder. Select the Hertz-Mundell-Fleming contact model, design the physical parameters as Poisson's ratio 0.28, static friction coefficient 0.4, rolling friction coefficient 0.01, and set the acceleration to 1.67m / s². 2 This ensures that the error of iterative calibration is less than 5%. The density of the core powder, the particle size of the coarse and fine powders, Poisson's ratio, static friction coefficient and rolling friction coefficient are input sequentially. Then, parameters such as acceleration and relative contact are set to simulate the flow rate of the core powder and output the results. The average particle size of the core powder is determined to be 105 μm, and the mass ratio of coarse to fine powder is approximately 5:1.

[0069] Then, aluminum powder, vanadium powder, molybdenum powder, iron powder, chromium powder, titanium powder, and titanium boride powder were placed in a vacuum drying oven at 140°C and a vacuum degree of 10. -3 ~10 -2 The powder was dried under Pa for 2.5 hours. The dried powder was then vacuum ball-milled using a planetary ball mill with zirconium balls as the milling medium, a ball-to-powder ratio of 15:1, a rotation speed of 250 r / min, and a milling time of 2.5 hours. The powder was then sieved through an 80-120 mesh screen to obtain the core powder, which was then stored in an argon atmosphere.

[0070] A TA1 titanium strip with a width of 10 mm and a thickness of 0.5 mm is rolled into a U-shaped groove on a roller die, and flux-cored powder is filled into the U-shaped groove to obtain a blank flux-cored welding wire with a diameter of 3.3 mm to 3.4 mm and a filling rate of 30%. The blank flux-cored welding wire is rolled and drawn to obtain a raw welding wire with a diameter of 3.0 mm to 3.1 mm.

[0071] Step 2, Roller Drawing and Annealing: The original welding wire from Step 1 is subjected to six sets of roller drawing for progressive diameter reduction. The deformation during roller drawing is 60%. Then, vacuum annealing is performed to eliminate work hardening, with a vacuum degree not exceeding 5×10⁻⁶. -3 Pa, temperature 650℃, holding time 2.0h, to obtain intermediate welding wire with a diameter of 2.0mm~2.1mm;

[0072] Step 3: Roller drawing: The intermediate welding wire obtained in Step 2 is continuously drawn through four sets of roller dies to gradually reduce its diameter. After surface polishing, a high-strength titanium alloy flux-cored welding wire with a diameter of 1.2 mm is obtained.

[0073] The application of the high-strength titanium alloy flux-cored welding wire for additive manufacturing in this embodiment is as follows: After surface treatment, the high-strength titanium alloy flux-cored welding wire is loaded into the arc wire additive manufacturing equipment. The working parameters are adjusted and argon gas is filled for protection. Then, additive manufacturing is carried out with a peak current of 140A, a base current of 90A, an arc voltage of 16V, a wire feed speed of 0.5m / min, an interpass interval of 60s, a lift of 1.8mm, and an interpass temperature not exceeding 150℃ to obtain a titanium alloy block.

[0074] The mechanical properties and elemental content of the titanium alloy bulk material (deposited state) produced by additive manufacturing using the titanium alloy flux-cored welding wire prepared in this embodiment were tested, and the results are shown in Tables 5 and 6 below.

[0075] Table 5

[0076]

[0077] As shown in Table 5, the high-strength titanium alloy flux-cored wire prepared in this embodiment has moderate strength and plasticity, and is a titanium alloy flux-cored wire with excellent comprehensive performance.

[0078] Table 6

[0079]

[0080] As shown in Table 6, the titanium alloy products obtained by additive manufacturing of the high-strength titanium alloy flux-cored wire prepared in this embodiment have a uniform distribution of major elements, especially oxygen content exceeding 0.1%. Because oxygen greatly improves the strength of the β phase of the titanium alloy through strong solid solution strengthening effect, it changes the strength matching relationship between the α phase and the β phase, making the plastic deformation more uniform, avoiding premature local failure, and giving it both good strength and plasticity.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength titanium alloy flux-cored welding wire for additive manufacturing, characterized in that, The flux-cored wire of this titanium alloy is composed of the following components by mass percentage: aluminum powder 4.5%~5.0%, vanadium powder 2.8%~3.2%, molybdenum powder 5.3%~5.8%, iron powder 1.5%~1.7%, chromium powder 1.4%~1.6%, titanium boride powder 1%~3%, with the remainder being titanium powder and unavoidable impurities. The mass ratio of coarse powder to fine powder in the flux-cored wire is 4~5:1, wherein the coarse powder is titanium powder with a particle size of 53μm~150μm, and the remaining powder is fine powder with a particle size of 15μm~53μm, and the average particle size of the flux-cored wire is 15μm~150μm. The preparation method of the high-strength titanium alloy flux-cored welding wire for additive manufacturing includes the following steps: Step 1: Material Filling: Using EDEM software, preset the target composition of the core powder. Create a powder model with coarse titanium powder (53μm~150μm) and fine powder (15μm~53μm). Then, calculate the flowability of the core powder based on its velocity into the outer casing. Select the Hertz-Mundell-Fleming contact model, designing physical parameters such as Poisson's ratio of 0.28~0.3, static friction coefficient of 0.35~0.5, rolling friction coefficient of 0.01, and setting the acceleration to 1.67m / s². 2 This ensures that the error of iterative calibration is less than 5%. Then, based on the simulation scenario output results, the average particle size of the core powder and the mass ratio of coarse powder to fine powder are determined, and the core powder is prepared. The outer sheath of the titanium alloy flux-cored welding wire is rolled into a U-shaped groove on a rolling and drawing machine, and flux powder is filled into the U-shaped groove to obtain a blank flux-cored welding wire. The blank flux-cored welding wire is rolled and drawn to obtain the original welding wire. Step 2, Roller drawing and annealing: The original welding wire from Step 1 is rolled and drawn to gradually reduce its diameter, with a deformation of 50% to 60%. Then, surface cleaning and vacuum annealing are performed to eliminate work hardening, resulting in intermediate welding wire. Step 3: Roller drawing: The intermediate welding wire obtained in Step 2 is continuously drawn through a roller die to gradually reduce its diameter, with a deformation of 15%~20%. After surface polishing, a high-strength titanium alloy flux-cored welding wire is obtained.

2. The method for preparing a high-strength titanium alloy flux-cored welding wire for additive manufacturing according to claim 1, characterized in that, The mass percentages of each element in the unavoidable impurities are: C≤0.10%, N≤0.03%, H≤0.015%, O≤0.10%.

3. The method for preparing a high-strength titanium alloy flux-cored welding wire for additive manufacturing according to claim 1, characterized in that, The outer sheath of the titanium alloy flux-cored welding wire is TA1 titanium strip with a width of 8mm~10mm and a thickness of 0.3mm~0.5mm.

4. The method for preparing a high-strength titanium alloy flux-cored welding wire for additive manufacturing according to claim 1, characterized in that, The average particle size of the core powder determined in step one is 15μm~150μm. The preparation method of the core powder is as follows: aluminum powder, vanadium powder, molybdenum powder, iron powder, chromium powder, titanium powder, and titanium boride powder are placed in a vacuum drying oven and dried at 100℃~140℃ and a vacuum degree of 10. -3 Pa~10 -2 The powder was dried under Pa conditions for 1.5 to 2.5 hours, and then vacuum-milled using a planetary ball mill with zirconium balls as the milling medium, a ball-to-powder ratio of 15:1, a rotation speed of 150 to 250 r / min, and a milling time of 1.5 to 2.5 hours. After milling, the powder was sieved and stored in an argon atmosphere. The filling rate of the core powder in the U-shaped groove was 30% to 50%.

5. The method for preparing a high-strength titanium alloy flux-cored welding wire for additive manufacturing according to claim 1, characterized in that, The vacuum degree of the vacuum annealing in step two shall not exceed 5 × 10⁻⁶. -3 Pa, temperature 550℃~650℃, holding time 1.0h~2.0h.

6. The method for preparing a high-strength titanium alloy flux-cored welding wire for additive manufacturing according to claim 1, characterized in that, In step one, the diameter of the initial flux-cored welding wire is 3.3mm~3.4mm, and the diameter of the original welding wire is 3.0mm~3.1mm; in step two, the diameter of the intermediate welding wire is 2.0mm~2.1mm; and in step three, the diameter of the high-strength titanium alloy flux-cored welding wire is 1.2mm~1.6mm.

7. An application of a high-strength titanium alloy flux-cored welding wire for additive manufacturing, characterized in that, The high-strength titanium alloy flux-cored welding wire is prepared by the method described in any one of claims 1 to 6. After surface treatment, the high-strength titanium alloy flux-cored welding wire is loaded into an arc-fused wire additive manufacturing equipment. The working parameters are adjusted and inert gas is filled for protection to carry out additive manufacturing, thereby obtaining a titanium alloy product.

8. The application according to claim 7, characterized in that, The additive manufacturing process parameters are as follows: peak current 140A~180A, base current 90A~100A, arc voltage 16V~26V, wire feed speed 0.5m / min~1.2m / min, interlayer interval time 60s~70s, lift 1.8mm~2.0mm, and interlayer temperature not exceeding 150℃.

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