Low-stress welding manufacturing method for additive titanium alloy component

Abstract

The invention provides a low-stress welding manufacturing method for additive titanium alloy components. The low-stress welding manufacturing method comprises the steps that a first additive titanium alloy component to be welded and a second additive titanium alloy component to be welded are prepared, and the component surfaces corresponding to the to-be-welded positions of the first additive titanium alloy component and the second additive titanium alloy component are cleaned; the first additive titanium alloy component and the second additive titanium alloy component are placed in a vacuum cabin and clamped and positioned, and a welding gap is formed between the first additive titanium alloy component and the second additive titanium alloy component; after the vacuum chamber is vacuumized, the welding gap is welded through a vacuum laser welding device to form a welding component; the welded component is placed in a cryogenic medium to be subjected to cryogenic treatment, so that contraction deformation, structure stabilization and defect repair of the welded component are achieved; and low-temperature heat treatment is conducted on the welded component obtained after subzero treatment, the set temperature of low-temperature heat treatment is T, and T is larger than or equal to 400 DEG C and smaller than or equal to 700 DEG C. According to the method, the cooperative regulation and control method for the multiple residual stresses of the additive titanium alloy component can be achieved, the high-precision and low-stress titanium alloy welding component is obtained, the welding quality is improved, and the high-precision manufacturing requirement of the component is met.

Description

Technical Field

[0001] This invention belongs to the field of vacuum laser welding technology, and specifically relates to a low-stress welding manufacturing method for additive titanium alloy components. Background Technology

[0002] Titanium alloys, such as TA15, possess high specific strength and high-temperature stability, making them widely used in complex load-bearing components in aerospace applications. However, due to the high reactivity, high resistance to deformation, and low thermal conductivity of titanium alloys, manufacturing complex thin-walled components using traditional processes is extremely challenging. Additive manufacturing technologies such as Laser Powder Bed Fusion (L-PBF), with their flexible processing and design capabilities, provide a powerful means to overcome the limitations of traditional processing methods and manufacture complex thin-walled titanium alloy components.

[0003] As aerospace component manufacturing continues to evolve towards complex curved surfaces, one-piece molding, and multi-functional integration, traditional segmented processing and multi-process assembly methods are gradually revealing numerous bottlenecks in areas such as residual stress, welding deformation, and high-precision manufacturing. This is particularly true in the manufacturing of large-sized complex components, thin-walled dissimilar material splicing structures, and multi-curvature channel parts, where problems such as high heat input, residual stress accumulation, and difficulty in welding deformation severely restrict the forming accuracy and manufacturing stability of components. This is especially prominent in the manufacturing of large-sized complex components represented by TA15 titanium alloy. The traditional "additive-laser welding" method, due to the high heat input of the atmospheric environment during welding and the high-temperature heat treatment after welding, makes it difficult to achieve coordinated control of the entire additive and welding process. This leads to the accumulation of residual stress under multiple thermal cycles, resulting in quality risks such as structural deformation, crack initiation, or fluctuations in interface strength.

[0004] Currently, TA15 additive titanium alloy components exhibit anisotropy, high initial residual stress, and unique lamellar microstructure. They lack a residual stress control mechanism for low heat input and small deformation. While some welding platforms utilize laser welding, optimization typically focuses solely on the welding process, lacking a synergistic control mechanism addressing anisotropy, high initial residual stress, and fine lamellar microstructure. Furthermore, the commonly used high-temperature heat treatment and post-weld heat treatment regimes often fail to meet the high dimensional accuracy requirements of high-precision, complex additive components after high-temperature heat treatment (exceeding 800℃), thus failing to meet the high-precision manufacturing demands. This singular control regime struggles to address the challenges of high welding heat input, large residual stress, significant welding deformation, or uncontrollable metallurgical defects in the manufacture of highly complex structures, impacting the high precision and repeatability of the welding manufacturing process.

[0005] The welding of additive titanium alloy components requires consideration not only of weld formation and path planning, but also of welding heat input, welding residual stress, and overall component dimensional accuracy. In traditional methods, high-energy-density atmospheric laser welding of highly reactive titanium alloy additive components can only protect localized areas of the weld, easily leading to hydrogen and oxygen absorption and subsequent weld joint performance degradation. Furthermore, the lack of multi-system heat treatment methods to regulate welding residual stress, coupled with a single heat treatment regime and a lack of multi-layered synergy and adaptive capabilities, severely hinders technological breakthroughs in the high-quality, high-efficiency integrated manufacturing of aerospace components. Summary of the Invention

[0006] Therefore, the present invention provides a low-stress welding manufacturing method for additive titanium alloy components, which can overcome the shortcomings of the existing technology in the welding process of multi-layer additive titanium alloy components, which has high heat input, large residual stress, and single welding heat treatment methods, resulting in large stress and large deformation of the components after welding, and cannot meet the high-precision manufacturing requirements of the components.

[0007] To address the above problems, the present invention provides a low-stress welding manufacturing method for additive titanium alloy components, comprising the following steps:

[0008] Prepare the first and second additive titanium alloy components to be welded and clean the surface of the components corresponding to the welding positions.

[0009] The first additive titanium alloy component and the second additive titanium alloy component are placed in a vacuum chamber and clamped and positioned, forming a weld gap between the first additive titanium alloy component and the second additive titanium alloy component.

[0010] After the vacuum chamber is evacuated, a laser welding device is used to perform laser welding on the weld seam to form a welded component.

[0011] The welded component is placed in a cryogenic medium for cryogenic treatment to achieve shrinkage deformation, microstructure stabilization and defect repair of the welded component;

[0012] The welded components after cryogenic treatment are subjected to low-temperature heat treatment. The set temperature for low-temperature heat treatment is T, where 400℃≤T≤700℃.

[0013] In some embodiments, the cryogenic medium is one of liquid nitrogen and liquid helium; and / or, during the welding process, the first additive titanium alloy component and the second additive titanium alloy component are locked together in a direction perpendicular to the weld seam.

[0014] In some embodiments, the cooling rate of the cryogenic treatment is selected based on A = W1 / t + W2 / T lIn the process, A represents the recommended cooling rate for cryogenic treatment, W1 is the first adjustment coefficient, W2 is the second adjustment coefficient, t is the thickness of the welded component, and T is the thickness of the welded component. l The temperature of the cryogenic medium to be used is selected; and / or, the locking torque is 200N-400N.

[0015] In some embodiments, the set temperature T conforms to T=T0+(γ1· Δσ+γ2· t), where T0 is the initial temperature of the low-temperature heat treatment, γ1 is the first empirical adjustment coefficient, γ2 is the second empirical adjustment coefficient, Δσ is the stress release target value within the current heat treatment regime, and t is the thickness of the welded component.

[0016] In some embodiments, the absolute pressure of the vacuum chamber during laser welding ranges from 0.1 Pa to 100 Pa.

[0017] In some embodiments, the laser welding device uses a fiber laser with a laser power of 2kW-30kW, a welding speed of 0.5m / min-5m / min, a spot diameter of 0.2mm-0.6mm, and a defocusing amount of -20mm-20mm.

[0018] In some embodiments, cryogenic treatment is performed by cooling to -196°C to -269°C at a rate of 1°C / min to 10°C / min and holding at this temperature for 1 to 24 hours.

[0019] In some embodiments, both the first additive titanium alloy component and the second additive titanium alloy component are tubular components, and rigid supports are provided in each tubular component at positions corresponding to the clamping positions before clamping and positioning them; and / or, the width of the weld gap does not exceed 0.5 mm.

[0020] In some embodiments, a rotary chuck is used to clamp and position the first and second additive titanium alloy components, wherein the coaxial runout of the rotary chuck is within ±0.1mm and the end face runout is within ±0.1mm; and / or, the weld gap is an annular gap, and the overlap between the start and end points of the laser beam in laser welding is 10mm-50mm.

[0021] In some embodiments, ribs are formed on the outer walls of the first and second additive titanium alloy components; and / or, a convex ring is formed on the end face to be welded of one of the first and second additive titanium alloy components, wherein the convex ring has a convex width of 1mm-3mm and a ring wall thickness of 0.1-0.3 times the wall thickness of the pipe to which it is connected.

[0022] The low-stress welding manufacturing method for additive titanium alloy components provided by this invention has the following beneficial effects:

[0023] First, laser welding of titanium alloy components is performed in a vacuum environment, i.e., vacuum laser welding. This suppresses plume vapor and achieves low heat input welding. At the same time, the vacuum environment provides a purer environment for titanium alloy welding, effectively preventing hydrogen and oxygen absorption in the weld, thus ensuring the performance of the weld joint. This fundamentally reduces the generation of residual welding stress and achieves the strength and toughness of the weld joint. Then, cryogenic treatment pre-induces shrinkage deformation in the welded component, putting it in a "high-energy, metastable" state to achieve higher efficiency and a lower temperature threshold. Finally, the cryogenically treated welded component undergoes low-temperature heat treatment. Through low-temperature heat treatment, atomic diffusion is driven at the weld joint, resulting in stress relaxation and stabilization. This produces a weld joint with optimized microstructure and stress state, thus realizing a multi-method residual stress control for additive titanium alloy components. This yields high-precision, low-stress titanium alloy welded components, improves welding quality, and meets the high-precision manufacturing requirements of the components. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the steps in the low-stress welding manufacturing method for additive titanium alloy components of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0028] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90° or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0029] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0030] See Figure 1 As shown in the embodiment of the present invention, a low-stress welding manufacturing method for additive titanium alloy components is provided, comprising the following steps:

[0031] Prepare the first and second additive titanium alloy components to be welded and clean the surface of the components corresponding to the welding positions. For example, first wipe with alcohol and then wipe with acetone to clean the welding surface and weld position until there are no obvious stains visible to the naked eye.

[0032] The first and second additive titanium alloy components are placed in a vacuum chamber (i.e., a vacuum space capable of accommodating the aforementioned components, positioning devices, laser welding devices, etc.) and clamped and positioned. A weld gap is formed between the first and second additive titanium alloy components. The structural shape of the weld gap varies depending on the structural form of the components. For example, the first and second additive titanium alloy components can be plates, in which case the weld gap is a straight gap. The first and second additive titanium alloy components can also be pipes, in which case the weld gap is an annular gap. Depending on the actual welding requirements, the weld gap can also have other more complex shapes, such as wavy, stepped, etc.

[0033] After the vacuum chamber is evacuated, a laser welding device is used to perform laser welding on the weld seam to form a welded component. Specifically, the aforementioned laser welding device is set on a corresponding motion device. The laser welding gun of the laser welding device is driven by a five-axis vacuum motor, which can realize high-precision path setting for complex paths.

[0034] The welded component is placed in a cryogenic medium for cryogenic treatment to utilize the extreme low temperature environment to activate the phase transformation potential and shrinkage deformation mechanism of the material, thereby achieving shrinkage deformation, microstructure stabilization and defect repair of the welded component.

[0035] The welded components after cryogenic treatment are subjected to low-temperature heat treatment. The set temperature for the low-temperature heat treatment is T, where 400℃≤T≤700℃. It is understood that the corresponding set temperature for conventional heat treatment of titanium alloy components in the prior art is 700℃-900℃.

[0036] In this technical solution, firstly, laser welding of titanium alloy components is performed in a low-vacuum environment, i.e., vacuum laser welding. The low-vacuum environment can suppress plume vapor and increase the absorption rate of laser energy, thereby achieving low heat input welding. At the same time, the vacuum environment provides a purer environment for titanium alloy welding, effectively avoiding hydrogen and oxygen absorption in the weld, thus ensuring the performance of the weld joint, fundamentally reducing the generation of welding residual stress and achieving the strength and toughness of the weld joint. Then, cryogenic treatment is performed, that is, the welded component is pre-deformed by using a cryogenic medium to induce shrinkage deformation, so that the welded component is in a "high-energy, metastable" state, in order to achieve preliminary stress relaxation with higher efficiency and a lower temperature threshold. Finally, the cryogenically treated welded component is subjected to low-temperature heat treatment. Through low-temperature heat treatment, atomic diffusion is driven at the weld joint of the welded component, and stress relaxation and stabilization treatment are obtained, achieving a weld joint with optimized microstructure and stress state. This realizes a multi-residual stress synergistic control method for additive titanium alloy components, obtaining high-precision, low-stress titanium alloy welded components, improving welding quality, and meeting the high-precision manufacturing requirements of components.

[0037] It should be particularly emphasized that the aforementioned welding manufacturing method of this application is particularly suitable for additive titanium alloy components formed by selective laser melting technology (i.e., laser powder bed melting additive manufacturing technology), especially for TA15 additive titanium alloy components that have anisotropy, high initial residual stress and unique lamellar structure characteristics, and can significantly improve the accuracy of welding and reduce residual stress.

[0038] It should be noted that cryogenic treatment alone mainly relies on phase transformation stress compensation and stress relaxation caused by low-temperature shrinkage, and its effect is limited. Low-temperature heat treatment alone, due to its low temperature, is insufficient to completely eliminate residual tensile stress in welding. Combining the two utilizes both the "phase transformation stress compensation" mechanism of cryogenic treatment and the "thermal activation stress relaxation" mechanism of heat treatment, achieving a 1+1>2 effect. While high-temperature heat treatment (such as stress-relief annealing) can eliminate residual stress significantly, titanium alloys are prone to microstructure coarsening, grain boundary weakening, or surface oxidation at high temperatures, which may even alter the performance balance of the welded joint. The "cryogenic + low-temperature heat treatment" combined process completes stress control at a temperature far below the phase transformation point, avoiding the above risks and representing a "low-temperature and efficient" stress control method.

[0039] In some embodiments, the cryogenic medium is either liquid nitrogen or liquid helium. Preferably, liquid nitrogen is used as the cryogenic medium because it is versatile and can reduce manufacturing costs.

[0040] In some embodiments, the cooling rate of the cryogenic treatment is selected based on A = W1 / t + W2 / T l In the process, A represents the recommended cooling rate for cryogenic treatment, with a recommended value of 1℃ / min - 10℃ / min. The specific value can be further optimized based on the material of the welded components. W1 is the first adjustment coefficient, in mm / min. 1= 1~5 mm / min, W2 is the second adjustment coefficient, in ℃ / min, W2=-200℃ / min~-400 ℃ / min, t is the thickness of the welded component (plate thickness when the welded component is a plate, pipe wall thickness when the welded component is a pipe), in mm, T l The temperature of the cryogenic medium is selected, expressed in °C. In practical applications, a more suitable cooling rate for cryogenic treatment can be chosen based on the thickness of the welded component and the selected cryogenic medium temperature. This ensures that the cooling rate is not too fast, which could lead to cracking or other adverse effects, nor too slow, which would reduce economic efficiency. It is understood that a corresponding temperature control unit is configured to ensure that the cooling rate of the cryogenic medium is maintained at approximately the aforementioned A.

[0041] In some implementations, the set temperature T conforms to T = T0 + (γ1 · Δσ + γ2 · t), where T0 is the initial temperature of the low-temperature heat treatment, typically room temperature (20°C), γ1 is the first empirical adjustment coefficient (°C / MPa), γ1 = 0.5-2°C / MPa, γ2 is the second empirical adjustment coefficient (°C / mm), γ2 = 20-40°C / mm, Δσ is the target stress release value within the current heat treatment regime (MPa), and t is the thickness of the welded component (mm). This ensures a better match between the set temperature of the low-temperature heat treatment, the target stress release value, and the thickness of the welded component, thereby improving the final welding effect.

[0042] In some embodiments, during the welding process, the first additive titanium alloy component and the second additive titanium alloy component are locked in a direction perpendicular to the weld gap, so that the weld gap can be as small as possible and remain stable at a small value, thereby further improving the welding quality. The aforementioned locking can be achieved using a torque wrench. In some embodiments, the locking torque is 200N-400N to prevent the weld width from deforming too much due to insufficient locking torque, and the titanium alloy component from being squeezed and deformed due to excessive locking torque.

[0043] In some embodiments, the absolute pressure range of the vacuum chamber during laser welding is from 0.1 Pa to 100 Pa. It should be noted that the laser absorption rate gradually increases as the pressure decreases, but the effect plateaus below a certain value. Therefore, below 0.1 Pa, the effect of increasing penetration depth and reducing heat input is not significant, and it will instead greatly increase equipment costs. Similarly, if the pressure is above 100 Pa, the effect of increasing penetration depth is also not significant; the best effect is achieved only within the range of 0.1 Pa to 100 Pa.

[0044] In some embodiments, the laser welding device employs a fiber laser (in one specific embodiment, a high-power red laser) with a laser power of 2kW-30kW, a welding speed of 0.5m / min-5m / min, a spot diameter of 0.2mm-0.6mm, and a defocusing amount of -20mm-20mm. This enables the laser welding device of the present invention to be suitable for welding additive parts with a wall thickness of approximately 3-30mm, preventing the occurrence of sagging or incomplete penetration of the welded sample.

[0045] In some implementations, cryogenic treatment is performed by cooling to -196°C to -269°C at a rate of 1°C / min to 10°C / min and holding at this temperature for 1 to 24 hours to prevent thermal shock caused by excessively rapid cooling, which could lead to cracking in severe cases.

[0046] As mentioned above, in some embodiments, both the first and second additive titanium alloy components can be plates. Of course, in other embodiments, both the first and second additive titanium alloy components are pipes. In this case, before clamping and positioning them, rigid supports are provided in each pipe at positions corresponding to the clamping positions. The aforementioned rigid supports can be, for example, solid metal bodies whose outer circumferential shape and size are adapted to the shape and size of the inner wall of the pipe opening of the corresponding additive titanium alloy component. This can prevent the titanium alloy components from deforming due to uneven stress when the pipes are clamped. Preferably, the aforementioned solid metal body is also inserted into the welded end pipe openings of both the first and second additive titanium alloy components.

[0047] In some embodiments, a rotary chuck is used to clamp and position the first and second additive titanium alloy components. The coaxial runout of the rotary chuck is within ±0.1mm, and the end face runout is within ±0.1mm. This ensures the stability of the welding path and welding depth in laser welding. When the weld gap is an annular gap, the overlap between the start and end points of the laser beam in laser welding is 10mm-50mm to ensure the circumferential integrity of the weld, thereby improving the welding quality.

[0048] In some embodiments, the width of the weld gap does not exceed 0.5 mm to prevent the weld gap from being too wide, which would prevent the laser beam from reliably welding the additive titanium alloy components on both sides.

[0049] In some embodiments, ribs are formed on the outer wall of the first and second additive titanium alloy components to improve the structural deformation resistance of the components. The ribs include a rib ring extending around the center line of the component and ribs that intersect on the outer wall of the component. The ribs are formed using laser selective melting technology.

[0050] A raised ring is formed on the welding end face of one of the first and second additive titanium alloy components. The raised width of the raised ring is 1mm-3mm, and / or the wall thickness of the raised ring is 0.1-0.3 times the wall thickness of the pipe to which it is connected. That is, when the raised ring is connected to the welding end face of the first additive titanium alloy component, the wall thickness of the raised ring is 0.1-0.3 times the wall thickness of the pipe of the first additive titanium alloy component. This can prevent sagging during welding if the thickness is lower than the aforementioned range, and increase material costs if the thickness is higher than the aforementioned range. It should be noted that the wall thickness of the pipe of the first and second additive titanium alloy components is uniform.

[0051] In this technical solution, a convex ring is formed on the end face to be welded of one of the first additive titanium alloy components and the second additive titanium alloy component. The convex ring can be used to limit the positioning of the two additive titanium alloy components during the assembly process. At the same time, it can also form a locking bottom for the annular weld after the two components are locked, preventing the laser beam from penetrating outside the weld and ensuring the weld penetration while preventing laser burn-through.

[0052] The technical solution of the present invention is further illustrated below with reference to several embodiments and comparative examples:

[0053] Example 1:

[0054] To achieve the above objectives, the present invention mainly includes the following steps:

[0055] The first step is to print a support for the end face of the 3 mm thick additive TA15 titanium alloy component to be welded. The support is 1 mm wide, 0.5 mm thick, and spaced 50 mm apart.

[0056] Step 2: Fix one of the titanium alloy additive components (i.e., the first additive titanium alloy component mentioned above) with a chuck, and then set a rigid support inside the fixing position to prevent deformation during the tightening process, so as to achieve precise clamping of the titanium alloy additive component. The coaxial runout of the rotating chuck is within ±0.05 mm, and the end face runout is within ±0.05 mm.

[0057] Step 3: Wipe the welding surface and weld seam of the additive titanium alloy component with alcohol first, and then wipe the welding surface and weld seam with acetone until there are no obvious stains visible to the naked eye.

[0058] Step 4: Install another part of the titanium alloy additive component (i.e., the second additive titanium alloy component mentioned above) according to step 2 (i.e., the second step mentioned above). Clean the weld surface and welding position using the method in step 3 (i.e., the third step mentioned above). After the cleaning index is qualified, align it with the first part of the additive component. Make slight adjustments to the relative position so that the second additive component is aligned with the process support of the first additive component (i.e., the rib mentioned above). Cooperate with the second titanium alloy cylinder to make the two process supports join together. After clamping, the gap between the components (i.e., the weld gap mentioned above) is less than 0.2 mm and the weld surfaces are joined.

[0059] Step 5: Lock the two additive component titanium alloy cylinders, and use a torque wrench to lock them during the clamping process. The locking torque is 360 N, and record the locking force each time.

[0060] Step 6: A high-power red laser is installed inside the low-vacuum welding chamber (i.e., the aforementioned vacuum chamber); the laser head mounting assembly is equipped with a galvanometer function, with a galvanometer deflection angle of ±10°;

[0061] Step 7: Place the two additive titanium alloy components in a vacuum welding chamber, determine the weld start point of the two components, and then perform vacuum treatment; perform low-vacuum laser welding on the additive components, with the following welding parameters: welding power 3.0KW, defocusing amount of +3 mm, welding speed of 0.8 m / min. Rotate the turntable during the welding of the additive titanium alloy cylinder to achieve laser welding. The overlap between the start and end points of the laser beam during the low-vacuum welding process is 20 mm, and finally obtain the low-vacuum welded titanium alloy additive component.

[0062] Step 8: Perform cryogenic treatment on the additively welded components. The cryogenic treatment medium is liquid nitrogen, and the cryogenic holding time is 1 hour.

[0063] Step 9: The components after cryogenic treatment are subjected to vacuum heat treatment. The heat treatment regime is as follows: heating rate is 10 ℃ / min, heat treatment temperature is 500 ℃, holding time is 1 h, and the components are cooled to room temperature in the furnace. The test results are shown in Table 1.

[0064] Table 1. Inspection results of welded joints in additive manufacturing components

[0065]

[0066] Comparative Example 1:

[0067] The first step is to print a support for the end face of the 3 mm thick additive TA15 titanium alloy component to be welded. The support is 1 mm wide, 0.5 mm thick, and spaced 50 mm apart.

[0068] Step 2: Fix one of the titanium alloy additive components using a chuck, and then set a rigid support inside the fixing position to prevent deformation during the tightening process, so as to achieve precise clamping of the titanium alloy additive component. The coaxial runout of the rotating chuck is within ±0.05 mm, and the end face runout is within ±0.05 mm.

[0069] Step 3: Wipe the welding surface and weld seam of the additive titanium alloy component with alcohol first, and then wipe the welding surface and weld seam with acetone until there are no obvious stains visible to the naked eye.

[0070] Step 4: Install the other part of the titanium alloy additive component according to step 2. Clean the weld surface and welding position using the method in step 3. After the cleaning index is qualified, align it with the first part of the additive component. Make slight adjustments to the relative position so that the second additive component is aligned with the process support of the first additive component. The two process supports are combined by the second titanium alloy cylinder. After clamping, the gap between the components is less than 0.2 mm and the welding surfaces are connected.

[0071] Step 5: Lock the two additive component titanium alloy cylinders, and use a torque wrench to lock them during the clamping process. The locking torque is 360 N, and record the locking force each time.

[0072] Step 6: A high-power red laser is installed inside the atmospheric laser welding chamber; the laser head mounting assembly is equipped with a galvanometer function, and the galvanometer deflection angle is ±10°;

[0073] Step 7: Place the two additive titanium alloy components in an atmospheric welding chamber, determine the weld start point of the two components, and then perform vacuum treatment; perform low vacuum laser welding on the additive components, with the following welding parameters: welding power 6.0KW, defocusing amount of +3 mm, welding speed of 0.8 m / min. During the welding of the additive titanium alloy cylinder, rotate the turntable to achieve laser welding. The overlap between the start and end points of the laser beam during the welding process is 20 mm, and finally obtain the titanium alloy additive component welded in an atmospheric environment.

[0074] Step 8: Perform cryogenic treatment on the additively welded components. The cryogenic treatment medium is liquid nitrogen, and the cryogenic holding time is 1 hour.

[0075] Step 9: The components after cryogenic treatment are subjected to vacuum heat treatment. The heat treatment regime is as follows: heating rate is 10 ℃ / min, heat treatment temperature is 500 ℃, holding time is 1 h, and the components are cooled to room temperature in the furnace. The test results are shown in Table 2.

[0076] Table 2 Inspection Results of Welded Joints in Additive Manufacturing Components

[0077]

[0078] Comparing Table 2 with Table 1, it can be seen that the residual stress of welding under atmospheric conditions is higher and the welding deformation is greater (from 0.24 mm to 0.31 mm).

[0079] Comparative Example 2:

[0080] The first step is to print a support for the end face of the 3 mm thick additive TA15 titanium alloy component to be welded. The support is 1 mm wide, 0.5 mm thick, and spaced 50 mm apart.

[0081] Step 2: Fix one of the titanium alloy additive components using a chuck, and then set a rigid support inside the fixing position to prevent deformation during the tightening process, so as to achieve precise clamping of the titanium alloy additive component. The coaxial runout of the rotating chuck is within ±0.05 mm, and the end face runout is within ±0.05 mm.

[0082] Step 3: Wipe the welding surface and weld seam of the additive titanium alloy component with alcohol first, and then wipe the welding surface and weld seam with acetone until there are no obvious stains visible to the naked eye.

[0083] Step 4: Install the other part of the titanium alloy additive component according to step 2. Clean the weld surface and welding position using the method in step 3. After the cleaning index is qualified, align it with the first part of the additive component. Make slight adjustments to the relative position so that the second additive component is aligned with the process support of the first additive component. The two process supports are combined by the second titanium alloy cylinder. After clamping, the gap between the components is less than 0.2 mm and the welding surfaces are connected.

[0084] Step 5: Lock the two additive component titanium alloy cylinders, and use a torque wrench to lock them during the clamping process. The locking torque is 360 N, and record the locking force each time.

[0085] Step 6: A high-power red laser is installed in the low-vacuum welding chamber; the laser head mounting assembly is equipped with a galvanometer function, and the galvanometer deflection angle is ±10°;

[0086] Step 7: Place the two additive titanium alloy components in a vacuum welding chamber, determine the weld start point of the two components, and then perform vacuum treatment; perform low-vacuum laser welding on the additive components, with the following welding parameters: welding power 3.0KW, defocusing amount of +3 mm, welding speed of 0.8 m / min. Rotate the turntable during the welding of the additive titanium alloy cylinder to achieve laser welding. The overlap between the start and end points of the laser beam during the low-vacuum welding process is 20 mm, and finally obtain the low-vacuum welded titanium alloy additive component.

[0087] Step 8: The welded components were subjected to vacuum heat treatment. The heat treatment regime was as follows: heating rate of 10 ℃ / min, heat treatment temperature of 500 ℃, holding time of 1 h, and then cooled to room temperature in the furnace. The test results are shown in Table 3.

[0088] Table 3 Inspection Results of Welded Joints in Additive Manufacturing Components

[0089]

[0090] Comparing Table 3 and Table 1, it can be seen that the residual stress release effect of welded components is poor when deep cryogenic treatment is not used, indicating that deep cryogenic treatment helps to release residual stress.

[0091] Example 2:

[0092] The first step is to print a support for the end face of the 3 mm thick additive TA15 titanium alloy component to be welded. The support is 1 mm wide, 0.5 mm thick, and spaced 30 mm apart.

[0093] Step 2: Fix one of the titanium alloy additive components using a chuck, and then set a rigid support inside the fixing position to prevent deformation during the tightening process, so as to achieve precise clamping of the titanium alloy additive component. The coaxial runout of the rotating chuck is within ±0.05 mm, and the end face runout is within ±0.05 mm.

[0094] Step 3: Wipe the welding surface and weld seam of the additive titanium alloy component with alcohol first, and then wipe the welding surface and weld seam with acetone until there are no obvious stains visible to the naked eye.

[0095] Step 4: Install the other part of the titanium alloy additive component according to step 2. Clean the weld surface and welding position using the method in step 3. After the cleaning index is qualified, align it with the first part of the additive component. Make slight adjustments to the relative position so that the second additive component is aligned with the process support of the first additive component. The two process supports are combined by the second titanium alloy cylinder. After clamping, the gap between the components is less than 0.2 mm and the welding surfaces are connected.

[0096] Step 5: Lock the two additive component titanium alloy cylinders, and use a torque wrench to lock them during the clamping process. The locking torque is 360 N, and record the locking force each time.

[0097] Step 6: A high-power red laser is installed in the low-vacuum welding chamber; the laser head mounting assembly is equipped with a galvanometer function, and the galvanometer deflection angle is ±10°;

[0098] Step 7: Place the two additive titanium alloy components in a vacuum welding chamber, determine the weld start point of the two components, and then perform vacuum treatment; perform low-vacuum laser welding on the additive components, with the following welding parameters: welding power 3.0KW, defocusing amount of +3 mm, welding speed of 0.8 m / min. Rotate the turntable during the welding of the additive titanium alloy cylinder to achieve laser welding. The overlap between the start and end points of the laser beam during the low-vacuum welding process is 20 mm, and finally obtain the low-vacuum welded titanium alloy additive component.

[0099] Step 8: Perform cryogenic treatment on the additively welded components. The cryogenic treatment medium is liquid nitrogen, and the cryogenic holding time is 1 hour.

[0100] Step 9: The cryogenically treated components are subjected to vacuum heat treatment. The heat treatment regime is as follows: heating rate is 10 ℃ / min, heat treatment temperature is 600 ℃, holding time is 1 h, and the components are cooled to room temperature in the furnace. The test results are shown in Table 4.

[0101] Table 4 Inspection Results of Welded Joints in Additive Manufacturing Components

[0102]

[0103] Comparing Table 4 and Table 1, it can be seen that after the heat treatment temperature is increased from 500℃ to 600℃, the residual stress release is more obvious, decreasing from 438MPa to 344MPa. However, the welding deformation increases from 0.24mm to 0.26mm. It is understandable that in practical applications, it is necessary to comprehensively consider whether the main goal is to reduce residual stress or to reduce welding deformation.

[0104] Comparative Example 3:

[0105] The first step is to print a support for the end face of the 3 mm thick additive TA15 titanium alloy component to be welded. The support is 1 mm wide, 0.5 mm thick, and spaced 30 mm apart.

[0106] Step 2: Fix one of the titanium alloy additive components using a chuck, and then set a rigid support inside the fixing position to prevent deformation during the tightening process, so as to achieve precise clamping of the titanium alloy additive component. The coaxial runout of the rotating chuck is within ±0.05 mm, and the end face runout is within ±0.05 mm.

[0107] Step 3: Wipe the welding surface and weld seam of the additive titanium alloy component with alcohol first, and then wipe the welding surface and weld seam with acetone until there are no obvious stains visible to the naked eye.

[0108] Step 4: Install the other part of the titanium alloy additive component according to step 2. Clean the weld surface and welding position using the method in step 3. After the cleaning index is qualified, align it with the first part of the additive component. Make slight adjustments to the relative position so that the second additive component is aligned with the process support of the first additive component. The two process supports are combined by the second titanium alloy cylinder. After clamping, the gap between the components is less than 0.2 mm and the welding surfaces are connected.

[0109] Step 5: Lock the two additive component titanium alloy cylinders, and use a torque wrench to lock them during the clamping process. The locking torque is 360 N, and record the locking force each time.

[0110] Step 6: A high-power red laser is installed in the low-vacuum welding chamber; the laser head mounting assembly is equipped with a galvanometer function, and the galvanometer deflection angle is ±10°;

[0111] Step 7: Place the two additive titanium alloy components in a vacuum welding chamber, determine the weld start point of the two components, and then perform vacuum treatment; perform low-vacuum laser welding on the additive components, with the following welding parameters: welding power 3.0KW, defocusing amount of +3 mm, welding speed of 0.8 m / min. Rotate the turntable during the welding of the additive titanium alloy cylinder to achieve laser welding. The overlap between the start and end points of the laser beam during the low-vacuum welding process is 20 mm, and finally obtain the low-vacuum welded titanium alloy additive component.

[0112] Step 8: The welded components were subjected to vacuum heat treatment. The heat treatment regime was as follows: heating rate of 10 ℃ / min, heat treatment temperature of 500 ℃, holding time of 1 h, and then cooled to room temperature in the furnace. The test results are shown in Table 5.

[0113] Table 5 Inspection Results of Welded Joints in Additive Manufacturing Components

[0114]

[0115] Comparing Table 5 and Table 4, it can be seen that under the same 600℃ heat treatment conditions, the method of performing deep cryogenic pretreatment followed by post-weld heat treatment is superior to the method of not performing deep cryogenic pretreatment in terms of reducing residual stress and controlling welding deformation. In other words, performing deep cryogenic pretreatment followed by post-weld heat treatment yields better results.

[0116] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0117] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A method for manufacturing additive titanium alloy components using low-stress welding, characterized in that, Includes the following steps: Prepare the first and second additive titanium alloy components to be welded and clean the surface of the components corresponding to the welding positions. The first additive titanium alloy component and the second additive titanium alloy component are placed in a vacuum chamber and clamped and positioned, forming a weld gap between the first additive titanium alloy component and the second additive titanium alloy component. After the vacuum chamber is evacuated, a vacuum laser welding device is used to perform laser welding on the weld seam to form a welded component. The welded component is placed in a cryogenic medium for cryogenic treatment to achieve shrinkage deformation, microstructure stabilization and defect repair of the welded component; The welded components after cryogenic treatment are subjected to low-temperature heat treatment. The set temperature for low-temperature heat treatment is T, where 400℃≤T≤700℃.

2. The low-stress welding manufacturing method for additive titanium alloy components according to claim 1, characterized in that, The cryogenic medium is one of liquid nitrogen and liquid helium; and / or, during the welding process, ensure that the first additive titanium alloy component and the second additive titanium alloy component are locked together in a direction perpendicular to the weld seam.

3. The low-stress welding manufacturing method for additive titanium alloy components according to claim 2, characterized in that, The cooling rate for the cryogenic treatment is selected based on A = W1 / t + W2 / T l In the process, A represents the recommended cooling rate for cryogenic treatment, W1 is the first adjustment coefficient, W2 is the second adjustment coefficient, t is the thickness of the welded component, and T is the thickness of the welded component. l The temperature of the cryogenic medium to be used is selected; and / or, the locking torque is 200N-400N.

4. The low-stress welding manufacturing method for additive titanium alloy components according to claim 1, characterized in that, The set temperature T conforms to T=T0+(γ1· Δσ+γ2· t), where T0 is the initial temperature of the low-temperature heat treatment, γ1 is the first empirical adjustment coefficient, γ2 is the second empirical adjustment coefficient, Δσ is the stress release target value within the current heat treatment regime, and t is the thickness of the welded component.

5. The low-stress welding manufacturing method for additive titanium alloy components according to claim 1, characterized in that, The absolute pressure range of the vacuum chamber during laser welding is 0.1 Pa to 100 Pa.

6. The low-stress welding manufacturing method for additive titanium alloy components according to claim 1, characterized in that, The laser welding device uses a fiber laser with a laser power of 2kW-30kW, a welding speed of 0.5m / min-5m / min, a spot diameter of 0.2mm-0.6mm, and a defocusing amount of -20mm-20mm.

7. The low-stress welding manufacturing method for additive titanium alloy components according to claim 1, characterized in that, The cryogenic treatment is carried out as follows: cooling to -196°C to -269°C at a rate of 1°C / min to 10°C / min, and holding at this temperature for 1 to 24 hours.

8. The low-stress welding manufacturing method for additive titanium alloy components according to claim 1, wherein both the first additive titanium alloy component and the second additive titanium alloy component are tubular components, and rigid supports are provided in each tubular component at positions corresponding to the clamping positions before clamping and positioning; and / or, the width of the weld gap does not exceed 0.5 mm.

9. The low-stress welding manufacturing method for additive titanium alloy components according to claim 8, characterized in that, The first and second additive titanium alloy components are clamped and positioned using a rotary chuck, wherein the coaxial runout of the rotary chuck is within ±0.1mm and the end face runout is within ±0.1mm; and / or, the weld gap is an annular gap, and the overlap between the start and end points of the laser beam in laser welding is 10mm-50mm.

10. The low-stress welding manufacturing method for additive titanium alloy components according to claim 8, characterized in that, The first and second additive titanium alloy components have raised ribs formed on their outer walls; and / or, a raised ring is formed on the end face to be welded of one of the first and second additive titanium alloy components, the raised width of the raised ring being 1mm-3mm, and the wall thickness of the raised ring being 0.1-0.3 times the wall thickness of the pipe to which it is connected.

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