Arc additive manufacturing system and method based on non-continuous pulsed cold welding

Abstract

The application provides an arc additive manufacturing system and method based on non-continuous pulse cold welding, and the system comprises a non-continuous pulse cold welding welding gun, a wire feeding guide pipe, a wire feeder and a multi-axis motion platform; the non-continuous pulse cold welding welding gun is connected with the wire feeding guide pipe and the wire feeder, and is installed on the multi-axis motion platform; an arc welding wire and the non-continuous pulse cold welding welding gun are sequentially arranged from front to back; a tungsten electrode of the non-continuous pulse cold welding welding gun is connected with a negative electrode of a cold welding power supply, and a titanium alloy welding wire is connected with a positive electrode of the cold welding power supply. By means of the non-continuous pulse cold welding technology, the application can form a titanium alloy structural member with fine-grained and weak-textured characteristics in the arc additive manufacturing process by using simple equipment and structure; the fine-grained and weak-textured structure can significantly improve the strength, toughness and fatigue resistance of the titanium alloy, and has important significance for the application of high-performance titanium alloy components in the fields of aviation, aerospace, weapon equipment and other major equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metal manufacturing methods, in particular, to an electric arc additive manufacturing system and method based on non-continuous pulse cold welding, especially a titanium alloy fine-grain weak texture regulation system and method based on non-continuous pulse cold welding. BACKGROUND

[0002] Electric arc additive manufacturing is an additive manufacturing method that uses an electric arc as an energy source, melts the base material while feeding the welding wire raw material, and deposits layer by layer according to the slice path of the predetermined geometric shape, based on the "discrete-accumulation" principle to form an additive manufacturing geometric body. It has the advantages of low cost, high efficiency and high quality, and has gradually become an important preparation technology in the fields of aerospace, national defense weapons and equipment, and other high-tech fields. However, the traditional electric arc heat source is often formed by discharging between the tungsten electrode and the base material, or between the melting machine welding wire and the base material. There is an inevitable strong coupling relationship between the size of the electric arc heat source and the size of the molten pool. The high heat input caused by this electric arc additive manufacturing process will cause the additive manufacturing component to have millimeter-sized coarse columnar crystals spanning multiple deposition layers. At the same time, the lack of heterogeneous nucleation points in the molten pool and the strong composition undercooling ability of the solute elements, as well as the large temperature gradient at the front of the solid / liquid interface, make it more difficult to eliminate the coarse beta columnar crystals inside the additive body through conventional means, and form alpha strong texture characteristics, causing the "high strength and low plasticity" and anisotropy problem of mechanical properties, which seriously restricts the application of titanium alloy additive manufacturing components in future aerospace vehicles.

[0003] Therefore, the effective regulation of grain refinement and texture weakening has become a research hotspot and focus of current titanium alloy electric arc wire additive manufacturing. Current titanium alloy grain refinement researches are mostly focused on external auxiliary process strategies and alloy element regulation. For example, patent document CN107649682A discloses a method for refining laser additive manufacturing titanium alloy grains by ultrasonic impact and induction heating. The method uses induction heating combined with ultrasonic impact to increase the thickness of the plastic deformation layer, thereby enhancing the refinement degree and uniformity of titanium alloy grains, improving the mechanical properties of additive manufacturing titanium alloy, and reducing anisotropy. However, although this method can refine grains and improve mechanical properties, it requires complex equipment and operation steps, and the parameters of ultrasonic impact and induction heating must be adjusted according to specific conditions, otherwise the grain refinement degree and uniformity will be affected. Patent document CN117483786A discloses a method for refining electric arc additive manufacturing titanium alloy grains by adding Ni element. The method adds a certain amount of Ni element to the molten pool during electric arc additive manufacturing, thereby obtaining a titanium alloy component composed of fine equiaxed crystals, and significantly improving the tensile strength and microhardness of the component. However, the method has the disadvantage of difficulty in controlling the uniform distribution of Ni element in the component, and the optimal amount of Ni addition cannot be determined. Therefore, how to achieve grain refinement and texture weakening during titanium alloy electric arc additive manufacturing by a simple, efficient and low-cost method has become one of the key research directions.

[0004] The cold welding power supply is capable of accurately releasing the electrical energy stored in the capacitor in the form of a pulse arc between the tungsten electrode and the workpiece to be welded in a very short time. The extremely high temperature generated by this pulse arc in a short time can quickly melt the base material to form a molten pool. Compared with traditional methods, this method has the advantages of small heat input and dispersed thermal stress. However, if the cold welding power supply is directly used for additive manufacturing by starting an arc between the tungsten electrode and the base material, there is still a problem of coarse beta columnar crystals growing epitaxially along the base grain. On this basis, if the heat input of the arc heat source and the linear correlation between the remelting depth in the additive manufacturing process are changed, the problem of the top layer of fine equiaxed crystals being melted due to excessive remelting depth can be overcome, which is expected to achieve microcrystal regulation during titanium alloy electric arc additive manufacturing, overcome the anisotropy and insufficient plasticity caused by traditional coarse columnar crystals, and realize the design and preparation of titanium alloy electric arc additive manufacturing with controllable grain refinement.

[0005] In summary, the present application aims to design and prepare titanium alloy additive manufacturing components with internal grain refinement and texture weakening regulation. The non-continuous pulse cold welding method is used to decouple the energy input and remelting depth relationship by using pulse discharge between the tungsten electrode and the welding wire, to realize the organization regulation of the titanium alloy metallurgical process of electric arc wire additive manufacturing, to eliminate coarse beta columnar crystals and weaken the alpha strong texture characteristics, and to lay a theoretical foundation for the integrated forming of fine-grained and weak-textured titanium alloy in the field of aerospace. SUMMARY

[0006] In view of the defects in the prior art, the purpose of the present application is to provide an electric arc additive manufacturing method and system based on non-continuous pulse cold welding.

[0007] According to the present application, an electric arc additive manufacturing system based on non-continuous pulse cold welding is provided, comprising:

[0008] a non-continuous pulse cold welding torch, a wire feeding guide tube, a wire feeder, and a multi-axis motion platform;

[0009] The non-continuous pulse cold welding torch is connected to the wire feeding guide tube and the wire feeder, and is installed on the multi-axis motion platform;

[0010] The electric arc welding wire and the non-continuous pulse cold welding torch are sequentially arranged from front to back;

[0011] The tungsten electrode of the non-continuous pulse cold welding torch is connected to the negative electrode of the cold welding power supply, and the titanium alloy welding wire is connected to the positive electrode of the cold welding power supply.

[0012] Preferably, the non-continuous pulse cold welding torch is used to release the electrical energy stored in the capacitor in the tungsten electrode in the form of a pulse arc between the tungsten electrode and the metal workpiece in a protective atmosphere, so that the metal workpiece and the welding wire are fused to produce metallurgical bonding, and a single-layer deposition layer is formed by non-continuous pulse deposition.

[0013] Preferably, the multi-axis motion platform is used to change the trajectory to reciprocally additively manufacture and deposit, thereby forming an electric arc additive manufacturing component.

[0014] Preferably, the instantaneous pulse current of the non-continuous pulse cold welding torch is 10-800 A, the pulse time is 50-500 ms, and the pulse frequency is 1-10 Hz.

[0015] Preferably, the tungsten electrode material of the non-continuous pulse cold welding torch includes a cerium-tungsten electrode, and the electrode diameter is 1.6-2.4 mm. The tip of the tungsten electrode is ground into a 70-90° conical shape.

[0016] Preferably, the material of the titanium alloy welding wire includes Ti, Ti6Al4V, Ti-6.5Al-1.5Zr-3.5Mo-0.3Si, and Ti-5Al-2Sn-2Zr-4Mo-4Cr.

[0017] Preferably, the connection of the titanium alloy welding wire to the positive electrode of the cold welding power supply includes:

[0018] - the power supply electrode sheet is made into a roller shape, so that the welding wire can be fed by rolling and the circuit remains conductive;

[0019] The power supply sheet is connected with the wire feeding conduit, the wire feeding conduit is in contact with the welding wire to keep the circuit conductive;

[0020] The power supply electrode sheet is connected with the wire feeding machine roller, the wire feeding wheel is disconnected with the wire feeding machine to cut off part of the current path, so that the conductive path is formed between the power supply electrode sheet and the welding wire.

[0021] Preferably, the non-continuous pulse deposition includes single pass deposition in a periodic solidification manner by using pulse arc, the pulse frequency is 1-10 Hz, the wire feeding speed is matched with the pulse frequency, and the wire feeding speed is 200 mm / min-1500 mm / min.

[0022] Preferably, the stroke of the X-axis direction and the Y-axis direction of the multi-axis motion platform is 500 mm, the stroke of the Z-axis direction is 400 mm, the stroke accuracy is 0.01 mm, and the bearing load is 20 kg.

[0023] According to the arc additive manufacturing method based on the non-continuous pulse cold welding provided by the application, the method comprises the following steps:

[0024] Step S1: the non-continuous pulse cold welding torch, the wire feeding conduit, the wire feeding machine and the multi-axis motion platform are arranged in a mode that the arc welding wire is in front and the non-continuous pulse cold welding torch is in back, and the wire feeding angle is adjusted so that the welding wire can enter the molten pool;

[0025] Step S2: the tungsten electrode of the non-continuous pulse cold welding torch is connected with the negative electrode of the cold welding power supply, and the titanium alloy welding wire is connected with the positive electrode of the cold welding power supply;

[0026] Step S3: in a protective atmosphere, the electric energy stored in the capacitor in the tungsten electrode is released in the form of pulse arc between the tungsten electrode and the metal workpiece, so that the metal workpiece and the welding wire are fused to generate metallurgical bonding, and a single pass single layer deposition layer is formed in a non-continuous pulse deposition manner;

[0027] Step S4: the step S3 is repeated, and the additive manufacturing deposition is reciprocated by changing the trajectory of the multi-axis motion platform until a predetermined arc additive manufacturing component is formed.

[0028] Compared with the prior art, the application has the following beneficial effects:

[0029] 1、The non-continuous pulse cold welding technology can be used to form a titanium alloy structure with fine grain and weak texture characteristics in the arc additive manufacturing process by using simple equipment and structure.

[0030] 2、The application utilizes the non-continuous pulse cold welding technology, distinguishes from the discharge characteristics of the tungsten electrode and the base material in the traditional TIG welding process, realizes the decoupling of the heat source energy and the molten pool through the discharge between the tungsten electrode and the welding wire; the method overcomes the problems that the fine grains are difficult to remain due to the lack of heterogeneous nucleation points and the large remelting depth in the traditional titanium alloy arc additive manufacturing process, so that the manufacturing process is more optimized, and the manufacturing efficiency and material utilization are improved.

[0031] 3、The application can control the discharge intensity of the electric arc and the temperature of the molten pool by adjusting the pulse parameters (such as current, discharge time and pulse frequency) and the wire feeding speed, thereby reducing the burn loss rate of the titanium alloy in the manufacturing process, helping to maintain the chemical composition and performance stability of the titanium alloy, and improving the product quality.

[0032] 4、The application adopts titanium alloys including Ti, Ti-6Al-4V, TA15, Ti60 and the like, has a wide application range; at the same time, it is not only suitable for titanium alloy materials, but also can be applied to other metal materials, and has broad application prospects in preparing complex structural parts, repairing damaged components and the like.

[0033] Other beneficial effects of the application will be described in the specific embodiments through the introduction of specific technical features and technical solutions, and those skilled in the art should be able to understand the beneficial technical effects brought by the technical features and technical solutions through the introduction of the technical features and technical solutions. BRIEF DESCRIPTION OF DRAWINGS

[0034] Other features, objects and advantages of the application will become more apparent through reading the detailed description of the non-limiting embodiments with reference to the following drawings:

[0035] Figure 1 It is a schematic diagram of the method for controlling the fine grain and weak texture of the titanium alloy based on the non-continuous pulse cold welding arc additive manufacturing.

[0036] Figure 2 It is a grain morphology diagram of the longitudinal section of the deposited part under different additive manufacturing process methods.

[0037] Figure 3 It is an SEM diagram of the cross-section microstructure of the deposited part under the process condition of non-continuous pulse cold welding by discharging between the welding wire and the tungsten electrode.

[0038] Figure 4 It is an SEM diagram of the cross-section microstructure of the deposited part under the process condition of non-continuous pulse cold welding by discharging between the welding wire and the tungsten electrode.

[0039] Figure 5 It is an EBSD diagram of the deposited part under the process condition of non-continuous pulse cold welding by discharging between the welding wire and the tungsten electrode.

[0040] Figure 6To deposit an EBSD map of an additively manufactured part under conventional TIG process conditions. DETAILED DESCRIPTION

[0041] The application will be described in detail below with specific examples. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be noted that for those skilled in the art, without departing from the concept of the application, a number of changes and improvements can be made. These are within the scope of the present application.

[0042] Reference Figure 1 As shown in the figure, a non-continuous pulse cold welding based arc additive manufacturing method comprises:

[0043] Step A, the non-continuous pulse cold welding torch, the wire feeding guide pipe, the wire feeder and the multi-axis motion platform are assembled in the order of the arc welding wire in front and the non-continuous pulse cold welding torch behind, the wire feeding angle is adjusted to ensure that the welding wire can smoothly enter the molten pool; the instantaneous pulse current of the non-continuous pulse cold welding is 10-800A, the pulse time is 50-500ms, the pulse frequency is 1-10Hz, and the adjustment range of the wire feeding angle is 0-60°, so that the discharge between the tungsten electrode and the welding wire is ensured while the welding wire is normally fed into the molten pool.

[0044] Step B, the tungsten electrode of the non-continuous pulse cold welding torch is connected to the negative electrode of the cold welding power supply, and the titanium alloy welding wire is connected to the positive electrode of the cold welding power supply to provide a basis for arc discharge between the tungsten electrode and the welding wire; the tungsten electrode material is a cerium tungsten electrode with a diameter of 1.6-2.4mm, and the tip of the tungsten electrode is ground into a 70-90° cone. The titanium alloy includes Ti, Ti6Al4V, Ti-6.5Al-1.5Zr-3.5Mo-0.3Si, Ti-5Al-2Sn-2Zr-4Mo-4Cr, etc. At the same time, unlike the traditional casting processing method, the alloy composition can be appropriately optimized according to the unique non-equilibrium solidification, multi-layer multi-pass remelting characteristics and intrinsic online in-situ heat treatment in the arc additive manufacturing process, considering the element burning loss.

[0045] The connection mode of the welding wire connected to the positive electrode of the cold welding power supply includes various forms:

[0046] (1) The power electrode piece is made into a roller shape, which does not affect the rolling feeding of the welding wire, while the circuit maintains a conductive path;

[0047] (2) The power piece is connected to the wire feeding guide pipe, which uses the close contact between the wire feeding guide pipe and the welding wire to maintain a conductive path for the circuit;

[0048] (3) The power electrode piece is connected to the wire feeder roller, and the possible current path between the wire feeding wheel and the wire feeder is cut off, so that a conductive path is formed between the power electrode piece and the welding wire.

[0049] In summary, the way of using the arc between the tungsten electrode and the welding wire in the additive manufacturing process to decouple the positive correlation between the heat source energy and the remelting depth, so as to change the solidification characteristics, can be regarded as the connection mode herein.

[0050] Step C, in a protective atmosphere, the electric energy stored in the capacitor in the tungsten electrode is released instantaneously in the form of pulsed arc between the tungsten electrode and the workpiece, the extremely high temperature arc makes the metal workpiece and the welding wire quickly fuse, generates metallurgical bonding, and forms a single-layer deposition layer by single-channel deposition in a non-continuous pulsed deposition manner; the non-continuous pulsed deposition adopts pulsed arc to carry out single-channel deposition in a periodic solidification manner, the pulse frequency is 1-10 Hz, and the wire feeding speed is matched with the pulse frequency, which is 200 mm / min-1500 mm / min.

[0051] Step D, the operation of step C is repeated, and the arc additive manufacturing component is formed by changing the trajectory of the multi-axis motion platform to reciprocate additive manufacturing deposition, wherein the X and Y travel ranges of the multi-axis motion platform are 500 mm, the Z travel range is 400 mm, the travel accuracy is 0.01 mm, and the bearing load is 20 kg, so that the additive manufacturing deposition speed can be controlled in real time.

[0052] By means of the non-continuous pulsed cold welding technology, the titanium alloy structural member with fine-grain and weak texture characteristics can be formed in the arc additive manufacturing process by using simple equipment and structure; the fine-grain and weak texture structure can significantly improve the strength, toughness and fatigue resistance of the titanium alloy, and has important significance for the application of high-performance titanium alloy components in the fields of aviation, aerospace, weapon equipment and other major equipment.

[0053] Example 1

[0054] The embodiment provides a non-continuous pulsed cold welding based arc additive manufacturing TC4 titanium alloy fine-grain and weak texture regulation and control method, which comprises the following steps:

[0055] Step 1, the non-continuous pulsed cold welding torch, the gas protection drag cover, the wire feeding pipe, the wire feeder and the multi-axis motion platform are assembled in the mode that the arc welding wire and the wire feeding pipe are in front and the non-continuous pulsed cold welding torch and the gas protection drag cover are in back; the Ti-6Al-4V substrate is polished with 400-mesh sandpaper, the surface oil stains are removed with acetone and dried, and then the substrate is fixed and preheated to 200 DEG C; the non-continuous pulsed cold welding parameters are set as follows: the pulse current is 50 A, the instantaneous peak current can reach 100 A, the pulse time is 70 ms, and the wire feeding angle is adjusted to 30 DEG, so that the welding wire can smoothly enter the molten pool.

[0056] Step 2, for Ti6Al4V titanium alloy wire with a diameter of 1.2 mm, the Ti6Al4V wire is pickled with an aqueous solution (volume fraction) of 5% HF + 30% HNO3; finally, after uniform water washing to remove the pickling solution and drying, the surface dirt and oxide film are removed to avoid the introduction of impurities while ensuring the conductivity of the welding wire. The negative electrode of the cold welding power supply is connected with the tungsten electrode, and the positive electrode power sheet is connected with the wire feeding guide tube. The wire feeding guide tube is in close contact with the welding wire to maintain the conductive path. The tungsten electrode is a cerium tungsten electrode, and the tip of the tungsten electrode is ground into a 70° conical angle to ensure normal pulse discharge. The elongation of the welding wire extending out of the guide tube is controlled to ensure that the tip of the welding wire is located directly below the cerium tungsten electrode and directly above the Ti-6Al-4V substrate, and the distance between the tip of the welding wire and the tip of the tungsten electrode is adjusted to 1.5 mm to realize stable pulse discharge between the tungsten electrode and the welding wire to form a molten pool to melt the welding wire. The deposition process is as shown in Figure 1

[0057] Step 3, move the welding gun to the starting point of the additive path, adjust the cold welding gun protection gas flow and the gas protection drag cover gas flow to 5 L / min and 16 L / min respectively, release the electrical energy stored in the capacitor in the tungsten electrode in the form of pulse arc between the tungsten electrode and the welding wire, the extremely high temperature arc melts the Ti-6Al-4V substrate and the welding wire quickly, and produces metallurgical bonding, the frequency of the discontinuous pulse arc is adjusted to 2 Hz, and the welding speed is 2.5 mm / s, a single-layer discontinuous pulse deposition layer is formed by a single-layer discontinuous pulse deposition method;

[0058] Step 4, lower the multi-axis walking platform by 0.8 mm to deposit the next layer on the basis of the original deposited layer. Steps 3 and 4 are repeatedly executed in a cycle until the multi-layer deposited metal reaches the preset shape and size, and a fine-grained weak texture characteristic titanium alloy is obtained. Figure 2 (a) is the grain morphology of the longitudinal section of the deposited part, it can be seen that the grain refinement degree is obvious, and the continuous growth trend of columnar grains is interrupted. Figure 3 It is an internal organization diagram, it can be seen that the size of the alpha platelet is small, and there is a rapidly cooled martensite phase. Figure 5 (a) is the EBSD diagram of the longitudinal section of the deposited part, it can be seen that the grain refinement is obvious, and the internal alpha texture feature is significantly weakened.

[0059] Example 2

[0060] The embodiment provides a non-discontinuous pulse cold welding based arc additive manufacturing Ti-6.5Al-1.5Zr-3.5Mo-0.3Si titanium alloy fine-grained weak texture regulation method, including the following steps:

[0061] ​Step 1, the non-continuous pulse cold welding torch, gas protection drag cover, wire feeder, wire feeder and multi-axis motion platform, according to the electric arc welding wire and the wire feeder in front, the non-continuous pulse cold welding torch and the gas protection drag cover behind the way tool. The Ti-6.5Al-1.5Zr-3.5Mo-0.3Si substrate is polished with 400 grit sandpaper, the surface oil is removed with acetone and dried, and then preheated to 200℃. Set the non-continuous pulse cold welding parameters: pulse current is 50A, pulse time is 50ms, adjust the wire feeding angle to 30°, ensure that the welding wire can smoothly enter the molten pool.

[0062] Step 2, for Ti-6.5Al-1.5Zr-3.5Mo-0.3Si titanium alloy wire with a diameter of 1.2mm, use 5%HF+30%HNO3 aqueous solution(volume fraction) to pickle Ti-6.5Al-1.5Zr-3.5Mo-0.3Si wire; finally, uniformly rewash to remove the pickling solution and dry for standby, remove the surface oil and oxide film, avoid the introduction of impurities while ensure the conductivity of the welding wire. The negative electrode of the cold welding power supply is connected with the tungsten electrode, and the positive electrode power sheet is connected with the wire feeder. The wire feeder is in close contact with the welding wire, so that the circuit keeps conductive path. The tungsten electrode adopts cerium tungsten electrode, and the tip of the tungsten electrode is ground into a 70° conical angle to ensure normal pulse discharge. Control the elongation of the welding wire extending out of the wire guide tube to ensure that the tip of the welding wire is located directly below the cerium tungsten electrode and directly above the Ti-6.5Al-1.5Zr-3.5Mo-0.3Si substrate, and adjust the distance between the tip of the welding wire and the tip of the tungsten electrode to 1.5mm to realize pulse discharge between the tungsten electrode and the welding wire to form a molten pool to melt the welding wire.

[0063] Step 3, move the welding torch to the starting point of the additive path, adjust the cold welding torch protection gas flow and the gas protection drag cover gas flow to 5L / min and 16L / min respectively, release the electric energy stored in the capacitor in the tungsten electrode in the form of pulse arc between the tungsten electrode and the workpiece, the extremely high temperature arc makes the Ti-6.5Al-1.5Zr-3.5Mo-0.3Si substrate and the welding wire quickly weld, and produces metallurgical bonding. Adjust the frequency of the non-continuous pulse arc to 2Hz and the welding speed to 3mm / s to form a single-layer non-continuous pulse deposition layer by non-continuous pulse deposition.

[0064] Step 4, lower the multi-axis walking platform by 0.8mm to deposit the next layer on the basis of the original deposited layer. Repeat steps 3 and 4 until the multi-layer deposited metal reaches the preset shape and size to obtain an arc additive manufacturing titanium alloy component with fine grain and weak texture characteristics.

[0065] Example 3

[0066] The embodiment provides a method for controlling fine-grain and weak-texture of TC4 titanium alloy based on non-continuous pulse cold welding arc additive manufacturing, and comprises the following steps.

[0067] Step 1, the non-continuous pulse cold welding torch, the gas protection drag cover, the wire feeding pipe, the wire feeder and the multi-axis motion platform are assembled according to the mode that the arc welding wire and the wire feeding pipe are in front and the non-continuous pulse cold welding torch and the gas protection drag cover are in back. The Ti-6Al-4V substrate is polished with 400 mesh sandpaper, and after the surface oil stain is removed by acetone and dried, the Ti-6Al-4V substrate is preheated to 200 DEG C. The non-continuous pulse cold welding parameters are set as follows: the pulse current is 100 A, the pulse time is 50 ms, and the wire feeding angle is adjusted to 30 DEG, so that the welding wire can smoothly enter the molten pool.

[0068] Step 2, for the Ti6Al4V titanium alloy wire with a diameter of 1.2 mm, the Ti6Al4V wire is pickled by using a water solution of 5% HF+30% HNO3 (volume fraction); finally, the Ti6Al4V wire is uniformly washed with water to remove the pickling solution and dried, so that the surface oil stain and oxide film are removed, impurities are avoided to be introduced, and the conductivity of the welding wire is ensured. The negative electrode of the cold welding power supply is connected with the tungsten electrode, and the positive electrode power sheet is connected with the wire feeding pipe, so that the wire feeding pipe and the welding wire are in close contact, and the electric circuit is kept in the conductive path. The tungsten electrode is a cerium tungsten electrode, and the tip of the tungsten electrode is ground into a 70 DEG conical angle, so that the normal pulse discharge is ensured. The elongation of the welding wire extending out of the wire feeding pipe is controlled, so that the tip of the welding wire is located directly below the cerium tungsten electrode and directly above the Ti-6Al-4V substrate, and the distance between the tip of the welding wire and the tip of the tungsten electrode is adjusted to 1.5 mm, so that the pulse discharge between the tungsten electrode and the welding wire forms the molten pool to melt the welding wire and deposit.

[0069] Step 3, the welding torch is moved to the starting point of the additive path, the cold welding torch protection gas flow and the gas protection drag cover gas flow are adjusted to 5 L / min and 16 L / min respectively, the electric energy stored in the capacitor in the tungsten electrode is released in the form of pulse arc between the tungsten electrode and the workpiece, the high-temperature arc makes the Ti-6Al-4V substrate and the welding wire rapidly fuse and weld, and a metallurgical bond is generated, the frequency of the non-continuous pulse arc is adjusted to 5 Hz, the welding speed is 3 mm / s, and a single-layer non-continuous pulse deposition layer is formed by the non-continuous pulse deposition mode.

[0070] Step 4, the multi-axis walking platform is lowered by 0.6 mm, so that the next layer is deposited on the basis of the original deposited layer. Steps 3 and 4 are repeatedly executed, until the multi-layer deposited metal reaches the preset shape and size, and a fine-grain and weak-texture characteristic titanium alloy arc additive manufacturing component is obtained.

[0071] Example 4

[0072] The embodiment provides a method for controlling fine-grain and weak texture of arc additive manufacturing TC4 titanium alloy based on non-continuous pulse cold welding, and comprises the following steps.

[0073] Step 1, the non-continuous pulse cold welding torch, the gas protection drag cover, the wire feeding pipe, the wire feeder and the multi-axis motion platform are assembled according to the mode that the arc welding wire and the wire feeding pipe are in front and the non-continuous pulse cold welding torch and the gas protection drag cover are in back. The Ti-6Al-4V substrate is polished with 400 mesh sandpaper, the surface oil stain is removed by acetone and dried, and then the Ti-6Al-4V substrate is preheated to 200 DEG C. The non-continuous pulse cold welding parameters are set as follows: the pulse current is 100 A, the pulse time is 70 ms, and the wire feeding angle is adjusted to 30 DEG, so that the welding wire can smoothly enter the molten pool.

[0074] Step 2, for the Ti6Al4V titanium alloy wire with a diameter of 2 mm, the Ti6Al4V wire is pickled by using a water solution of 5% HF+30% HNO3 (volume fraction); finally, the pickling solution is removed by water washing and drying, the surface oil stain and oxide film are removed, and the conductivity of the welding wire is ensured. The negative electrode of the cold welding power supply is connected with the tungsten electrode, and the positive electrode power sheet is connected with the wire feeding pipe. The wire feeding pipe is in close contact with the welding wire, so that the circuit keeps conductive. The tungsten electrode is a cerium tungsten electrode, and the tip of the tungsten electrode is ground into a 70 DEG conical angle, so as to ensure normal pulse discharge. The elongation of the welding wire extending out of the wire guide pipe is controlled, so that the tip of the welding wire is located directly below the cerium tungsten electrode and directly above the Ti-6Al-4V substrate, and the distance between the tip of the welding wire and the tip of the tungsten electrode is 2 mm, so as to realize pulse discharge between the tungsten electrode and the welding wire to form a molten pool to melt the welding wire and deposit.

[0075] Step 3, the welding torch is moved to the starting point of the additive path, the cold welding torch protection gas flow and the gas protection drag cover gas flow are adjusted to 5 L / min and 16 L / min respectively, the electric energy stored in the capacitor in the tungsten electrode is released instantaneously in the form of pulse arc between the tungsten electrode and the workpiece, the high-temperature arc makes the Ti-6Al-4V substrate and the welding wire rapidly weld, and a metallurgical bond is generated. The frequency of the non-continuous pulse arc is adjusted to 2 Hz, and the welding speed is 2.5 mm / s. A single-layer non-continuous pulse deposition layer is formed by the non-continuous pulse deposition mode.

[0076] Step 4, the multi-axis walking platform is lowered by 1 mm, so as to deposit the next layer on the basis of the original deposited layer. Steps 3 and 4 are repeatedly executed in cycles until the multi-layer deposited metal reaches the preset shape and size, and a fine-grain and weak-texture arc additive manufacturing titanium alloy component is obtained.

[0077] Example 5

[0078] The embodiment provides a fine-grain weak-texture regulation method of Ti-5Al-2Sn-2Zr-4Mo-4Cr titanium alloy based on non-continuous pulse cold welding arc additive manufacturing, and comprises the following steps.

[0079] Step 1, the non-continuous pulse cold welding torch, the gas protection drag cover, the wire feeding guide pipe, the wire feeder and the multi-axis motion platform are tooling in the mode that the arc welding wire and the wire feeding guide pipe are in front and the non-continuous pulse cold welding torch and the gas protection drag cover are in back. The Ti-5Al-2Sn-2Zr-4Mo-4Cr substrate is polished with 400 mesh sandpaper, the surface oil stains are removed by acetone and dried, and then the Ti-5Al-2Sn-2Zr-4Mo-4Cr substrate is preheated to 200 DEG C. The non-continuous pulse cold welding parameters are set as follows: the instantaneous pulse current is 100 A, the pulse time is 50 ms, the wire feeding angle is adjusted to 30 DEG, and it is ensured that the welding wire can smoothly enter the molten pool.

[0080] Step 2, for the Ti-5Al-2Sn-2Zr-4Mo-4Cr titanium alloy wire with a diameter of 0.8 mm, the Ti-5Al-2Sn-2Zr-4Mo-4Cr wire is pickled by using a 5% HF+30% HNO3 aqueous solution (volume fraction); finally, the pickling solution is removed by water washing and drying, the surface oil stains and oxide films are removed, and the conductivity of the welding wire is ensured. The negative electrode of the cold welding power supply is connected with the tungsten electrode, and the positive electrode power sheet is connected with the wire feeding guide pipe. The wire feeding guide pipe is in close contact with the welding wire, so that the circuit keeps conductive. The tungsten electrode is a cerium tungsten electrode, and the tip of the tungsten electrode is ground into a 70 DEG conical angle, so as to ensure normal pulse discharge. The elongation of the welding wire extending out of the guide pipe is controlled, so that the tip of the welding wire is located directly below the cerium tungsten electrode and directly above the Ti-5Al-2Sn-2Zr-4Mo-4Cr substrate, and the distance between the tip of the welding wire and the tip of the tungsten electrode is 1.5 mm, so as to realize pulse discharge between the tungsten electrode and the welding wire to form a molten pool to melt the welding wire and deposit.

[0081] Step 3, the welding torch is moved to the starting point of the additive path, the cold welding torch protection gas flow and the gas protection drag cover gas flow are adjusted to 5 L / min and 16 L / min respectively, the electric energy stored in the capacitor in the tungsten electrode is released instantaneously between the tungsten electrode and the workpiece in the form of pulse arc, the extremely high temperature arc makes the Ti-5Al-2Sn-2Zr-4Mo-4Cr substrate and the welding wire rapidly weld, and a metallurgical bond is generated. The frequency of the non-continuous pulse arc is adjusted to 5 Hz, the welding speed is 4 mm / s, and a single-layer non-continuous pulse deposition layer is formed by the non-continuous pulse deposition mode.

[0082] Step 4, the multi-axis walking platform is lowered by 0.6 mm to deposit the next layer on the basis of the original deposited layer. Steps 3 and 4 are repeatedly executed in cycles until the multi-layer deposited metal reaches the preset shape and size, and a fine-grained weakly textured arc additive manufacturing titanium alloy component is obtained.

[0083] Comparative Example 1

[0084] The difference between the present comparative example and Example 1 is that a common TIG arc is used for Ti-6Al-4V additive manufacturing test, and the remaining steps are basically the same as those of Example 1. The Ti-6Al-4V substrate is polished with 400-mesh sandpaper, and after the surface oil stains are removed with acetone and dried, it is fixed and preheated to 200°C. The TIG additive manufacturing parameters are set as follows: the deposition current is 100 A, the welding speed is 3 mm / s, the wire feeding angle is adjusted to 30° to ensure that the welding wire can smoothly enter the molten pool. For Ti6Al4V titanium alloy wire with a diameter of 1.2 mm, the Ti6Al4V wire is pickled with a 5% HF + 30% HNO3 aqueous solution (volume fraction); finally, after water washing to remove the pickling solution and drying, the surface oil stains and oxide film are removed to avoid the introduction of impurities while ensuring the conductivity of the welding wire. The tungsten electrode is a cerium tungsten electrode, and the tip of the tungsten electrode is ground into a 70° conical angle to ensure normal discharge and arc striking. The welding torch is moved to the starting point of the additive path, and the TIG welding torch protection gas flow and the gas protection drag cover gas flow are adjusted to 12 L / min and 16 L / min, respectively. The tungsten electrode and the workpiece are discharged and arc struck, the Ti-6Al-4V substrate and the welding wire are rapidly welded by the extremely high temperature arc, and a metallurgical bond is formed. The wire feeding speed is set to 15 mm / s, and a single-layer non-continuous pulse deposition layer is formed by non-continuous pulse deposition. The multi-axis walking platform is lowered by 0.8 mm to deposit the next layer on the basis of the original deposited layer. Steps 3 and 4 are repeatedly executed in cycles until the multi-layer deposited metal reaches the preset shape and size, and an additive manufacturing titanium alloy deposition body is obtained. Figure 2 (c) The grain morphology of the longitudinal section of the common TIG arc additive manufacturing deposition part can be seen. The interior is coarse columnar grains growing through the deposited layer, and the columnar grain width is 1-2 mm. Figure 3 The internal structure diagram shows that the α platelets are large in size and form α colony organization with similar orientation. Figure 6(a) is the EBSD diagram of the longitudinal section of the deposited part, the alpha texture feature is obvious, and there is a strong preferred orientation feature, and according to the reconstruction of the original beta grain according to the burgers relationship, it can be seen that the shooting area is inside a beta grain. Therefore, during the Ti-6Al-4V additive manufacturing by using ordinary TIG arc, due to the lack of heterogeneous nucleation points in the molten pool and the large component undercooling of alloy elements, coarse beta columnar crystals growing through the deposition layer are easily formed in the additive manufacturing deposition body, and at the same time, there is a strong alpha texture feature, which further causes high strength and low plasticity, anisotropy, and affects the further development and application of additive manufacturing integrated titanium alloy structural parts.

[0085] Comparative Example 2

[0086] The difference between the present comparative example and Example 1 is that the Ti-6Al-4V pulse cold welding additive manufacturing test is carried out by adopting the mode of tungsten electrode connected to negative electrode and base material connected to positive electrode, and the rest of the steps are basically the same as Example 1. In the present comparative example, the non-continuous pulse cold welding torch, gas protection drag cover, wire feeding pipe, wire feeder and multi-axis motion platform are assembled in the mode of arc welding wire and wire feeding pipe in front, and non-continuous pulse cold welding torch and gas protection drag cover behind. The Ti-6Al-4V substrate is polished with 400 mesh sandpaper, the surface oil stain is removed with acetone and dried, and then preheated to 200°C. The non-continuous pulse cold welding parameters are set as follows: pulse current is 50A, instantaneous peak current can reach 100A, pulse time is 70ms, and wire feeding angle is adjusted to 30° to ensure that the welding wire can smoothly enter the molten pool. For Ti6Al4V titanium alloy wire with a diameter of 1.2mm, the wire is pickled with 5% HF+30% HNO3 aqueous solution (volume fraction); finally, after water washing to remove the pickling solution, the wire is dried for use, to remove surface oil stain and oxide film, avoid the introduction of impurities and ensure the conductivity of the welding wire. The negative electrode of the cold welding power supply is connected to the tungsten electrode, and the positive electrode is connected to the base material, so that the circuit remains conductive. The tungsten electrode is a cerium tungsten electrode, and the tip of the tungsten electrode is ground into a 70° conical angle to ensure normal pulse discharge and to realize stable pulse discharge between the tungsten electrode and the base material to form a molten pool to melt the welding wire. Move the welding torch to the starting point of the additive manufacturing path, adjust the cold welding torch protection gas flow and the gas protection drag cover gas flow to 5L / min and 16L / min respectively, release the electrical energy stored in the capacitor in the tungsten electrode in the form of pulse arc between the tungsten electrode and the workpiece, the extremely high temperature arc makes the Ti-6Al-4V substrate and the welding wire quickly melt and bond, and adjust the frequency of the non-continuous pulse arc to 2Hz and the welding speed to 3mm / s, to form a single-layer pulse deposition layer by non-continuous pulse deposition; lower the multi-axis walking platform by 0.8mm to deposit the next layer on the basis of the original deposition layer. Repeat steps 3 and 4 until the multi-layer deposited metal reaches the preset shape and size, to obtain a fine-grained weak texture titanium alloy additive body.Figure 2 (b) the longitudinal section grain morphology diagram of the deposition body obtained by additive manufacturing in the mode of tungsten electrode connecting negative electrode and base material connecting positive electrode, the beta grains have a partial refinement effect, and the grain size is 0.5mm-1.5mm. Therefore, the Ti-6Al-4V pulse cold welding additive manufacturing test is carried out in the mode of tungsten electrode connecting negative electrode and base material connecting positive electrode, the grains are refined to a certain extent, but the refinement is not obvious, the continuous growth of the coarse columnar grains cannot be blocked, the weakening and elimination of anisotropy have certain limitations, and it is difficult to realize the integrated preparation of the fine-grain weak-texture characteristic additive manufacturing titanium alloy component.

[0087] In summary, the additive manufacturing method provided by the present application changes the mode of traditional arc striking between the tungsten electrode and the base material, forms a pulse arc by striking between the tungsten electrode and the welding wire and using the form of pulse capacitor energy storage discharge, and additive forms the target component according to the planned path, can inhibit the coarse columnar grains grown along the substrate, promote the refinement of beta grains and alpha lamellar structure, weaken the alpha texture characteristics, make the component produce uniform plastic deformation, effectively eliminate the metallurgical defects and anisotropy characteristics of the component, and provide a reference mode for obtaining the integrated preparation of the fine-grain weak-texture characteristic arc additive titanium alloy component.

[0088] Those skilled in the art know that, in addition to implementing the system and each device, module and unit thereof provided by the present application in the form of pure computer readable program code, the same functions can also be realized by logically programming the method steps to make the system and each device, module and unit thereof provided by the present application in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers and embedded microcontrollers. Therefore, the system and each device, module and unit thereof provided by the present application can be considered as a hardware component, and the devices, modules and units included therein for realizing various functions can also be considered as structures in the hardware component. The devices, modules and units for realizing various functions can also be considered as both software modules realizing the method and structures in the hardware component.

[0089] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essential content of the present application. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. An electric arc additive manufacturing system based on non-continuous pulsed cold welding, characterized in that, The application relates to a non-continuous pulse cold welding torch, a wire feeding guide tube, a wire feeder and a multi-axis motion platform. The non-continuous pulse cold welding torch is connected with the wire feeding guide tube and the wire feeder based on the wire feeding guide tube and is installed on the multi-axis motion platform. The non-continuous pulse cold welding torch is connected with the wire feeding guide tube and the wire feeder based on the wire feeding guide tube and is installed on the multi-axis motion platform. The tungsten electrode of the non-continuous pulse cold welding torch is connected with the negative electrode of a cold welding power supply, and the titanium alloy welding wire is connected with the positive electrode of the cold welding power supply. The non-continuous pulse cold welding torch is used for releasing the electric energy stored in the capacitor in the tungsten electrode in the form of a pulse arc between the tungsten electrode and a metal workpiece in a protective atmosphere, so that the metal workpiece and the welding wire are fused to generate metallurgical bonding, a single-layer deposition layer is formed by single-pass deposition in a non-continuous pulse mode, and the single-layer deposition layer is formed by single-pass deposition in a non-continuous pulse mode. The instantaneous pulse current of the non-continuous pulse cold welding torch is 10-800 A, the pulse time is 50-500 ms, and the pulse frequency is 1-10 Hz. The trajectory of the multi-axis motion platform is changed to reciprocally deposit the additive manufacturing, so that the arc additive manufacturing component is formed.

2. The non-continuous pulsed cold-weld based electric arc additive manufacturing system of claim 1, wherein, The tungsten electrode material of the non-continuous pulse cold welding torch comprises a cerium-tungsten electrode, and the electrode diameter is 1.6-2.4 mm.

3. The non-continuous pulsed cold-weld based electric arc additive manufacturing system of claim 1, wherein, The material of the titanium alloy welding wire comprises Ti, Ti6Al4V, Ti-6.5Al-1.5Zr-3.5Mo-0.3Si and Ti-5Al-2Sn-2Zr-4Mo-4Cr.

4. The non-continuous pulsed cold-weld based electric arc additive manufacturing system of claim 1, wherein, The connection mode of the titanium alloy welding wire with the positive electrode of the cold welding power supply comprises the following modes:

5. The non-continuous pulsed cold-weld based electric arc additive manufacturing system of claim 1, wherein, The power supply electrode sheet is made into a roller shape, so that the welding wire can be rolled and fed, and the circuit keeps a conductive path. The power supply sheet is connected with the wire feeding guide tube, the wire feeding guide tube is in contact with the welding wire, and the circuit keeps a conductive path. The power supply electrode sheet is connected with the wire feeder roller, the part of the current path between the wire feeding wheel and the wire feeder is cut off, so that a conductive path is formed between the power supply electrode sheet and the welding wire. The non-continuous pulse deposition comprises single-pass deposition in a periodic solidification mode by using a pulse arc, the pulse frequency is 1-10 Hz, the wire feeding speed is matched with the pulse frequency, and the wire feeding speed is 200 mm / min-1500 mm / min.

6. The non-continuous pulsed cold-weld based electric arc additive manufacturing system of claim 1, wherein, The stroke of the multi-axis motion platform in the X-axis direction and the Y-axis direction is 500 mm, the stroke in the Z-axis direction is 400 mm, the stroke accuracy is 0.01 mm, and the bearing load is 20 kg.

7. The method of claim 1, wherein the method is a method of controlling the grain size and texture of titanium alloy by non-continuous pulsed cold-welding based arc additive manufacturing, characterized in that, The application further relates to a method for manufacturing an arc additive manufacturing component.

8. A method of arc additive manufacturing based on non-continuous pulsed cold welding, based on the system of arc additive manufacturing based on non-continuous pulsed cold welding according to any one of claims 1 to 7, characterized in that, Step S1: the non-continuous pulse cold welding torch, the wire feeding guide tube, the wire feeder and the multi-axis motion platform are assembled in the mode that the arc welding wire is in front and the non-continuous pulse cold welding torch is behind, and the wire feeding angle is adjusted so that the welding wire can enter the molten pool; Step S2: the tungsten electrode of the non-continuous pulse cold welding torch is connected with the negative electrode of the cold welding power supply, and the titanium alloy welding wire is connected with the positive electrode of the cold welding power supply; Step S3: in a protective atmosphere, the electric energy stored in the capacitor in the tungsten electrode is released in the form of a pulse arc between the tungsten electrode and a metal workpiece, so that the metal workpiece and the welding wire are fused to generate metallurgical bonding, and a single-layer deposition layer is formed by single-pass deposition in a non-continuous pulse mode; Step S4: step S3 is repeated, the trajectory of the multi-axis motion platform is changed to reciprocally deposit the additive manufacturing, and a predetermined arc additive manufacturing component is formed. ​

Images