A method for manufacturing TC4 titanium alloy components based on plasma arc wire deposition

Abstract

This invention discloses a manufacturing method for TC4 titanium alloy components based on plasma arc wire deposition, comprising the following steps: Step 1: Calculate the weight of the blank; Step 2: Melt the wire using a plasma arc as the heat source in an argon-protected atmosphere; Step 3: Deposit to obtain the blank; Step 4: Mill the outer surface of the blank; Step 5: Coat the surface of the blank with glass lubricant; Step 6: Perform a first hot deformation treatment to obtain a first-deformed part; Step 7: Heat preservation treatment; Step 8: Perform a second hot deformation treatment to obtain a second-deformed part; Step 9: Anneal the second-deformed part. This invention prepares TC4 titanium alloy blanks through plasma arc wire deposition and, through two hot deformation treatments, repeatedly breaks and refines the grains, improving the inhomogeneity of the microstructure and the anisotropy of mechanical properties, thereby achieving rapid, low-cost, short-cycle, and high-performance manufacturing of TC4 titanium alloy components.

Description

Technical Field

[0001] This invention belongs to the field of metal component manufacturing, and particularly relates to a manufacturing method for TC4 titanium alloy components based on plasma arc wire deposition. Background Technology

[0002] Titanium and titanium alloys possess excellent physical and chemical properties such as low density, high specific strength, high temperature resistance, and corrosion resistance, making them among the most promising metallic materials in modern aerospace and shipbuilding. However, titanium alloys suffer from poor machinability, complex manufacturing processes, low production efficiency, and high processing costs, classifying them as typical difficult-to-machine materials. The use of titanium alloy wire melt deposition modeling technology to manufacture large-size titanium alloy components offers significant advantages, including low manufacturing cost, short cycle time, high density, and high material utilization, attracting considerable attention from research institutions and industry applications. While high-energy electron beams and laser beams are limited by the high cost of equipment such as vacuum chambers and lasers, plasma arcs offer high energy density and low equipment cost, making them suitable for low-cost manufacturing.

[0003] Titanium alloy components were formed using plasma arc wire deposition. The initial crystal structure near the substrate was equiaxed, but as the deposition height increased, the β-grains grew, exhibiting coarse, epitaxial columnar grains. Under the influence of thermal cycling, the microstructure became inhomogeneous. The top of the formed component contained acicular α′ martensite, while the middle and lower parts contained abundant Widmanstätten structure, basketweave structure, lamellar structure, and a small amount of residual α′ martensite, which could not be controlled by subsequent heat treatment processes. Macroscopically, the formed component exhibited inhomogeneous mechanical properties: high tensile strength and low plasticity perpendicular to the deposition direction, and low tensile strength and high plasticity parallel to the deposition direction.

[0004] Therefore, refining the grain size of titanium alloy wire melt deposition forming components, improving the microstructure, and enhancing the overall mechanical properties of the components have become key technologies that urgently need to be addressed for the application of titanium alloy wire melt deposition forming technology in the fields of aerospace, shipbuilding, and weaponry. Summary of the Invention

[0005] The purpose of this invention is to provide a manufacturing method for TC4 titanium alloy components based on plasma arc wire deposition, in order to solve the problem of uneven mechanical properties of the formed components, namely, high tensile strength and low plasticity perpendicular to the deposition direction, while low tensile strength and high plasticity parallel to the deposition direction.

[0006] This invention adopts the following technical solution: a manufacturing method for TC4 titanium alloy components based on plasma arc wire deposition, comprising the following steps:

[0007] Step 1: Calculate the weight of the blank part based on the actual weight of the component and the proportional coefficient.

[0008] Step 2: Weigh out an equal weight of wire based on the weight of the blank, and melt the wire in an argon protective atmosphere using a plasma arc as the heat source.

[0009] Step 3: Deposit the blank layer by layer on the substrate according to the two-dimensional cross-sectional path of the CAD model, and then separate the blank from the substrate. The original β grain size of the blank is 1-40 mm.

[0010] Step 4: Mill the outer surface of the blank to remove oxide scale and pits, making the surface of the blank smooth, flat, and free of cracks.

[0011] Step 5: Apply glass lubricant to the surface of the blank to prevent it from sticking together during deformation and to reduce friction.

[0012] Step 6: Place the heated blank in the mold for the first heat deformation treatment to obtain a deformed part, which causes the original β grains of the blank to deform and break.

[0013] Step 7: Place the deformed part in a heating furnace for heat treatment to allow the deformed and fractured grains to grow, resulting in a deformed part with uniform grain size.

[0014] Step 8: Place the primary deformed part with uniform grain size into the mold for a second heat deformation treatment to obtain the secondary deformed part, so that the grains of the primary deformed part with uniform grain size are broken up uniformly again.

[0015] Step 9: Anneal the secondary deformed part, then machine it to remove the surface oxide layer, defects and excess material to obtain the final titanium alloy component.

[0016] Furthermore, the method for the first heat deformation treatment in step 6 consists of the following steps:

[0017] Step 601: Heat the blank in a heating furnace to 50–100°C above the (α+β) / β phase transformation point, and hold at that temperature for 0.5–3 hours. The (α+β) / β phase transformation point is obtained by differential thermal analysis.

[0018] Step 602: Place the heated blank in the mold for the first heat deformation treatment, with a deformation amount of 40% to 70%.

[0019] Further, in step 2, the filament is composed of the following components by mass percentage: Al: 5.5-6.75%, V: 3.5-4.5%, Fe≤0.22%, C≤0.05%, N≤0.03%, H≤0.012%, Y≤0.005%, O: 0.1%-0.18%, with the balance being Ti and other impurity elements.

[0020] Furthermore, the heat preservation treatment method in step 7 is as follows: the heating furnace is heated to the (α+β) / β phase transition temperature and kept at that temperature for 3 to 40 hours.

[0021] Furthermore, the formula for calculating the weight of the blank in step 1 is: G = η·G0, where G is the weight of the blank, G0 is the actual weight of the component, and η is a proportionality coefficient of 1.5 to 3.0.

[0022] Furthermore, in step 3, the CAD model is obtained by reverse engineering the actual component in three dimensions and increasing one side by 1-3 mm.

[0023] Furthermore, the deformation amount of the second hot deformation treatment in step 8 is 30% to 50%.

[0024] The beneficial effects of this invention are:

[0025] 1. This invention prepares TC4 titanium alloy blanks by plasma arc wire deposition forming, and then performs two hot deformation treatments to repeatedly crush and refine the grains, thereby improving the non-uniformity of the microstructure and the anisotropy of mechanical properties, so as to achieve rapid, low-cost, short-cycle, and high-performance manufacturing of TC4 titanium alloy components.

[0026] 2. Compared with traditional titanium alloy component manufacturing, this invention eliminates the need for multiple melting and forging of TC4 ingots. It uses metal wire melting deposition forming technology to achieve near-net-shape forming of TC4 titanium alloy die forging blanks, reducing manufacturing processes, shortening the manufacturing cycle, and lowering manufacturing costs.

[0027] 3. Compared with the traditional titanium alloy smelting process, the present invention completes the primary smelting and purification of TC4 titanium alloy during the plasma arc wire deposition forming process of TC4 titanium alloy, thereby further reducing impurity elements.

[0028] 4. Compared with existing metal wire melting deposition forming, this invention rapidly prepares blanks based on TC4 plasma arc melting deposition forming technology. Through the combination of hot deformation treatment and heat treatment technology, coarse grains are refined and the microstructure is improved, resulting in uniform microstructure and mechanical properties of TC4 titanium alloy components. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the TC4 titanium alloy component of Embodiment 1 of the present invention;

[0030] Figure 2 The metallographic structure of the TC4 titanium alloy blank prepared in Example 1 of this invention;

[0031] Figure 3 The metallographic microstructure of the TC4 titanium alloy component prepared in Example 1 of this invention. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0033] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0034] This invention discloses a method for manufacturing TC4 titanium alloy components based on plasma arc wire deposition, comprising the following steps:

[0035] Step 1: Calculate the weight of the blank part based on the actual weight of the component and the proportional coefficient.

[0036] The formula for calculating the weight of the blank in step 1 is: G = η·G0, where G is the weight of the blank, G0 is the actual weight of the component, and η is a proportionality coefficient of 1.2 to 2.0.

[0037] Step 2: Weigh out an equal weight of wire based on the weight of the blank, and melt the wire in an argon atmosphere using a plasma arc as the heat source.

[0038] The filament in step 2 is composed of the following components by mass percentage: Al: 5.5-6.75%, V: 3.5-4.5%, Fe≤0.22%, C≤0.05%, N≤0.03%, H≤0.012%, Y≤0.005%, O: 0.1%-0.18%, with the balance being Ti and other impurity elements.

[0039] Plasma arc deposition is performed using a fused wire in an argon-protected atmosphere. The plasma arc current is 150–220 A, the voltage is 9–15 V, and the wire diameter is [missing information]. The wire feeding speed is 1.2–3.0 m / min, the feed rate is 8–14 mm / s, the layer thickness is 1.0–3.0 mm, and the oxygen content in the overall argon protective atmosphere is ≤50 ppm.

[0040] Step 3: Deposit the blank layer by layer on the substrate according to the two-dimensional cross-sectional path of the CAD model, and separate the blank from the substrate. The original β grain size of the blank is 1-40 mm. The CAD model of the blank is obtained by reverse engineering of the actual component in three dimensions and increasing by 1-3 mm on one side.

[0041] Step 4: Mill the outer surface of the blank to remove the oxide scale and pits, so that the surface of the blank is smooth, flat and free of cracks.

[0042] Step 5: Apply glass lubricant to the surface of the blank to prevent the blank from sticking together during deformation and to reduce friction.

[0043] Step 6: Place the heated blank in the mold for the first heat deformation treatment to obtain a deformed part, so that the original β grains of the blank are deformed and broken.

[0044] Step 7: Place the primary deformed part in a heating furnace for heat preservation treatment to allow the deformed and broken grains to grow, so as to obtain a primary deformed part with uniform grain size.

[0045] Step 8: Place the primary deformed part with uniform grain size into the mold for a second heat deformation treatment to obtain a secondary deformed part, so that the grains of the primary deformed part with uniform grain size are broken up uniformly again.

[0046] Step 9: Anneal the secondary deformed part, then machine it to remove the surface oxide layer, defects and excess material to obtain the final titanium alloy component.

[0047] Example 1

[0048] Step 1: Based on the TC4 titanium alloy square thin-walled component with wall thickness δ = 3mm, single side length L = 150mm, height h = 150mm, and weight G0 = 1.2kg, design the CAD model of the metal wire deposition forming blank, take the scale coefficient η = 2.5, and the weight of the blank G = 3.0kg.

[0049] Step 2: Select a diameter of The TC4 titanium alloy wire has the following chemical composition: Al: 6.15%, V: 3.98%, Fe: 0.14%, C: 0.008%, N: 0.005%, H: 0.0012%, Y: 0.002%, O: 0.12%. The TC4 titanium alloy wire was melted using a high-energy beam plasma arc under an overall argon protective atmosphere with an oxygen content of 20ppm.

[0050] Step 3: Slice the CAD model of the blank to obtain a two-dimensional cross-section, and plan the forming path on the two-dimensional cross-section. According to the planned path, use a high-energy beam plasma arc in an argon-sealed chamber to melt and deposit the TC4 titanium alloy wire, forming a two-dimensional cross-sectional layer of the blank. The oxygen content in the chamber is 20ppm. Repeat the melting and deposition of TC4 titanium alloy wire layer by layer until a three-dimensional blank is formed. Use wire cutting to separate the TC4 titanium alloy blank from the substrate.

[0051] The thickness of the formed blank was measured to be 12 mm. The average original β-grain sizes at the bottom, middle, and top of the component were 2 mm, 15 mm, and 3 mm, respectively. The metallographic structure of the blank is as follows: Figure 2As shown, the original β grains are coarse, columnar, with clear grain boundaries, and the grain interior contains a mixture of basketweave and Widmanstätten structures. Differential thermal analysis revealed the (α+β) / β phase transition point to be 980℃~985℃.

[0052] Step 4: Machin the surface of the blank to remove the oxide layer and pits, so that the surface is flat and the roughness is Ra3.2.

[0053] Step 5: Apply glass lubricant to the surface of the blank.

[0054] Step 6: Place the heated blank forging into a mold for the first hot deformation. The wall thickness of the first deformed part is 6mm.

[0055] Step 601: Heat the blank to 1050℃ in a heating furnace and hold for 30 minutes.

[0056] Step 602: Place the heated blank in the mold for the first heat deformation treatment, with a deformation amount of 50%.

[0057] Step 7: Heat the electric heating furnace to 980℃, then place the first-deformed part in the furnace and keep it at that temperature for 300 minutes.

[0058] Step 8: Place the first-deformed part into the mold for a second hot deformation. The wall thickness of the part after the second hot deformation is 4mm and the deformation is 33%.

[0059] Step 9: Place the component after secondary deformation in a heating furnace at 780℃ for recrystallization annealing, hold for 30 minutes, and then air cool.

[0060] Finally, machining is used to remove defects such as oxide scale and pits from the surface of the final titanium alloy component, resulting in the final TC4 titanium alloy component.

[0061] Metallographic structure of components such as Figure 3 As shown, the grain size is significantly reduced and is equiaxed. Its transverse and longitudinal mechanical properties are shown in Table 1. The tensile strength and yield strength are reduced to 2.4% and 3.8% respectively, and the elongation is higher than 10%. The various irregularities of the component are significantly improved.

[0062] Table 1 Mechanical properties of components

[0063]

[0064]

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing TC4 titanium alloy components based on plasma arc wire deposition, characterized in that, It consists of the following steps: Step 1: Calculate the weight of the blank part based on the actual weight of the component and the proportional coefficient. Step 2: Weigh out an equal weight of wire based on the weight of the blank, and melt the wire in an argon protective atmosphere using a plasma arc as the heat source. Step 3: Deposit the blank layer by layer on the substrate according to the two-dimensional cross-sectional path of the CAD model to obtain the blank, and then separate the blank from the substrate. The original β grain size of the blank is 1~40mm. Step 4: Mill the outer surface of the blank to remove oxide scale and pits, making the surface of the blank smooth, flat, and free of cracks. Step 5: Apply glass lubricant to the surface of the blank to prevent it from sticking together during deformation and to reduce friction. Step 6: Place the heated blank in the mold for the first heat deformation treatment to obtain a deformed part, which causes the original β grains of the blank to deform and break. Step 7: Place the deformed part in a heating furnace for heat treatment to allow the deformed and fractured grains to grow, resulting in a deformed part with uniform grain size. Step 8: Place the primary deformed part with uniform grain size into the mold for a second heat deformation treatment to obtain the secondary deformed part, so that the grains of the primary deformed part with uniform grain size are broken up uniformly again. Step 9: Anneal the secondary deformed part, then machine it to remove the surface oxide layer, defects and excess material to obtain the final titanium alloy component; The first heat deformation treatment in step 6 consists of the following steps: Step 601: Heat the blank in a heating furnace to 50~100℃ above the (α+β) / β phase transformation point and hold for 0.5~3 hours. The (α+β) / β phase transformation point is obtained by differential thermal analysis. Step 602: Place the heated blank in the mold for the first heat deformation treatment, with a deformation amount of 40%~70%.

2. The manufacturing method of TC4 titanium alloy components based on plasma arc wire deposition according to claim 1, characterized in that, The filament in step 2 is composed of the following components by mass percentage: Al: 5.5~6.75%, V: 3.5~4.5%, Fe≤0.22%, C≤0.05%, N≤0.03%, H≤0.012%, Y≤0.005%, O: 0.1%~0.18%, with the balance being Ti and other impurity elements.

3. The manufacturing method of TC4 titanium alloy components based on plasma arc wire deposition according to claim 2, characterized in that, The heat preservation method in step 7 is as follows: the heating furnace is heated to the (α+β) / β phase transition temperature and kept warm for 3~40 hours.

4. The manufacturing method of TC4 titanium alloy components based on plasma arc wire deposition according to claim 1, characterized in that, The formula for calculating the weight of the blank in step 1 is: G=η•G0, where G is the weight of the blank, G0 is the actual weight of the component, and η is a proportionality coefficient of 1.5~3.

0.

5. A method for manufacturing TC4 titanium alloy components based on plasma arc wire deposition according to any one of claims 1-4, characterized in that, The CAD model described in step 3 is obtained by reverse engineering the actual component in three dimensions and increasing one side by 1~3mm.

6. The method for manufacturing TC4 titanium alloy components based on plasma arc wire deposition according to claim 1, characterized in that, The deformation amount of the second hot deformation treatment in step 8 is 30%~50%.

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