Ti60 tissue regulation and control method based on ultrasonic energy field assisted laser direct energy deposition

Abstract

The invention discloses a Ti60 structure regulation and control method based on ultrasonic energy field assisted laser direct energy deposition, and belongs to the technical field of metal additive manufacturing. The method comprises the following steps: drying Ti60 powder; polishing and cleaning the surface of the substrate; starting ultrasound through the ultrasonic assembly, and adjusting frequency and power to enable the substrate to reach a resonance state; starting a water cooling device; powder carrying gas and protective gas are introduced; ensuring that the laser, the ultrasound and the Ti60 powder are converged at the same focus of the substrate; the method comprises the following steps: conveying Ti60 powder, starting laser, forming a stable molten pool on a substrate, and after deposition is finished, sequentially closing the laser and ultrasound, stopping conveying the Ti60 powder, and closing a water cooling device and protective gas, so as to prepare the Ti60 part with the fine equiaxed crystal structure. The water cooling device eliminates heat accumulation, ensures that the resonant frequency of the substrate is stable, and realizes a stable ultrasonic effect; and the metallurgical behavior of the molten pool is regulated and controlled through the cavitation effect and the acoustic streaming effect generated by ultrasound in the molten pool, and refining and regulation and control of the grain structure are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal additive manufacturing, and specifically relates to a Ti60 tissue control method based on ultrasonic energy field assisted laser direct energy deposition. Background Art

[0002] With the rapid development of global aerospace technology, the performance requirements for aircraft engines are increasing day by day. Among them, the thrust-to-weight ratio is one of the key indicators to measure engine performance. Its continuous improvement directly promotes the innovation of aircraft engine design and manufacturing technology. In this process, the compressor, as the core component of the aircraft engine, has a more stringent challenge to the high-temperature performance of the material due to the continuous increase in its outlet temperature. Although traditional high-temperature alloys have met the use requirements in high-temperature environments to a certain extent, their performance has gradually approached the limit in the face of working environments with higher temperatures and more complex stress states. Therefore, the research and development of new high-temperature materials with higher heat resistance, better thermal stability and lighter weight has become a key factor in promoting the advancement of aircraft engine technology. Near-α-type titanium alloys, especially high-performance titanium alloys such as Ti60, are regarded as an important material choice to replace some traditional high-temperature alloys and achieve lightweight aircraft due to their unique thermal strength and thermal stability, and their ability to work for a long time at 600℃ or even higher. These titanium alloys have shown broad application prospects in the fields of high-temperature components of aircraft engines and thermal protection systems of hypersonic aircraft, which are of great significance for improving the overall performance and reliability of aircraft.

[0003] For additive manufacturing of near-α titanium alloys such as Ti60, laser direct energy deposition (LDED) technology has attracted widespread attention in the aerospace field because it can directly form complex structures in an integrated manner according to the design model. LDED technology achieves rapid transformation from design to physical parts through layer-by-layer melting and deposition of powder materials, and is particularly suitable for large-scale rapid forming of large structural parts. However, the unique process characteristics of LDED, such as rapid cooling of micro-molten pools, large temperature gradient solidification, and layer-by-layer reciprocating reheating cycles, also bring about difficulties in microstructure control and performance optimization. In order to improve the microstructure of near-α titanium alloys such as Ti60 formed by LDED, researchers have tried a variety of methods, including periodically adjusting the scanning speed and laser power to obtain finer equiaxed crystal structures, and enhancing the mechanical properties of parts by adding alloying elements or ceramic particles. These studies have achieved results to a certain extent, but there are still problems such as coarse grain structure and obvious anisotropy of mechanical properties, and the addition of alloying elements may change the composition and performance balance of the original alloy.

[0004] Although LDED technology has shown great potential in the additive manufacturing of near-α titanium alloys, the current technology still faces a series of problems that need to be solved. First, due to the rapid solidification characteristics of the micro-melting pool during the LDED process, coarse columnar crystals that grow epitaxially along the deposition layer are prone to appear inside the parts. This anisotropic organizational feature seriously affects the mechanical properties and reliability of the parts. Secondly, although the organization can be improved to a certain extent by adjusting process parameters and adding alloying elements, these methods are often accompanied by increased process complexity and changes in alloy composition, which not only increases the manufacturing cost, but also may introduce new performance uncertainties. In addition, how to achieve effective organization refinement and comprehensive improvement of mechanical properties while maintaining the original excellent properties of the alloy is still a major technical problem in the field of LDED forming of near-α titanium alloys. Therefore, exploring a new method that is simple, efficient, and can take into account both organization refinement and performance improvement is of great significance to promoting the application of LDED technology in the field of high-performance titanium alloy additive manufacturing. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a Ti60 tissue control method based on ultrasonic energy field assisted laser direct energy deposition, so as to solve how to effectively refine and homogenize the grain structure of the part through the action of a stable ultrasonic energy field during the LDED forming process of the near-α-type titanium alloy Ti60, thereby overcoming the technical problems of coarse grain structure and obvious anisotropy of mechanical properties in traditional LDED technology.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention discloses a Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition, wherein an ultrasonic energy field assisted laser direct energy deposition device is used to regulate Ti60 tissue; the ultrasonic energy field assisted laser direct energy deposition device comprises a laser direct energy deposition forming device, a water cooling device and an ultrasonic energy field assisted device connected in sequence; the laser direct energy deposition forming device provides laser; the ultrasonic energy field assisted device comprises a substrate and an ultrasonic component connected to the substrate; the method comprises: Step 1: Drying Ti60 powder; Step 2: Polish and clean the substrate surface; Step 3: Turn on the ultrasound through the ultrasonic component, and adjust the frequency and power to make the substrate reach a resonant state; Step 4: Turn on the water cooling device wrapped around the substrate; Step 5: introducing powder-carrying gas and protective gas; Step 6: After ensuring that the laser, ultrasound and Ti60 powder converge at the same focus of the substrate; transport Ti60 powder, start the laser, form a stable molten pool on the substrate, and control the movement of the laser cladding head on the substrate surface to deposit multiple layers of metal. The metallurgical behavior of the molten pool is regulated by the cavitation effect and acoustic streaming effect generated by ultrasound in the molten pool; Step 7: After the deposition is completed, turn off the laser and ultrasound in turn, stop feeding the Ti60 powder, turn off the water cooling device and the protective gas, and obtain a Ti60 part with a fine equiaxed crystal structure.

[0007] Preferably, in step 1, Ti60 powder is prepared by a plasma rotating electrode method.

[0008] Preferably, in step 1, the particle size of the Ti60 powder is in the range of 53-150 μm.

[0009] Preferably, in step 1, the drying conditions are: drying at 80-150° C. for 2-3 h.

[0010] Preferably, in step 2, 500-1000 mesh sandpaper is used for polishing; and alcohol is used for cleaning.

[0011] Preferably, in step 3, the surface amplitude of the substrate reaching a resonant state is adjusted within a range of 0 to 9 μm.

[0012] Preferably, in step 4, thermally conductive glue is filled between the water cooling device and the substrate.

[0013] Preferably, in step 5, the powder-carrying gas is argon or helium; and the protective gas is argon or helium.

[0014] Preferably, in step 6, the powder feeding rate of Ti60 powder is 8-12 g / min; the energy deposition parameters of the laser include: laser power of 600-800 W, scanning speed of 8-12 mm / s, spot diameter of 3-5 mm, overlap rate between adjacent tracks of 50%-70%, and lifting amount of laser cladding head of 0.1-0.2 mm.

[0015] Preferably, the laser direct energy deposition forming device further comprises a powder feeding nozzle for conveying Ti60 powder; Laser melts Ti60 powder to form a molten pool on the substrate surface; laser, ultrasound and Ti60 powder converge in the molten pool; The water cooling device is a cooling tube wound around the base plate; The ultrasonic component comprises an ultrasonic horn, an ultrasonic transmitter and an ultrasonic energy controller which are sequentially connected to the substrate.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a Ti60 tissue control method based on ultrasonic energy field assisted laser direct energy deposition. Before the deposition test, the Ti60 powder is dried to remove the absorbed moisture, prevent the generation of defects such as pores during the laser cladding process, improve the compactness and mechanical properties of the deposited layer, ensure that the Ti60 powder used has a consistent composition and particle size distribution, which is the basis for obtaining a high-quality deposited layer, and complete the filling and substrate setting. The oxide layer, oil stains and other impurities on the surface of the substrate are removed by grinding, and the bonding force between the substrate and the deposited layer is improved. Cleaning further ensures the cleanliness of the substrate surface, reduces the presence of pollutants, and provides good interface conditions for subsequent deposition processes. The ultrasonic energy field is introduced to provide assistance for the subsequent laser cladding process. By accurately adjusting the frequency and power of the ultrasound, the substrate reaches a resonant state, which helps to produce stronger cavitation effects and acoustic streaming effects in the molten pool, thereby optimizing the metallurgical behavior of the molten pool. The present invention realizes the function by utilizing the resonant characteristics of the substrate under the action of ultrasound. However, the resonant frequency of the substrate will fluctuate with temperature changes. During the laser cladding process, the substrate will be subjected to high temperature. Turning on the water cooling device can effectively eliminate the heat generated during the deposition process, thereby ensuring the stability of the resonant frequency. This measure ensures that a stable ultrasonic effect can be maintained during the LDED forming process; effectively reduces the heat accumulation of the substrate to keep the resonant frequency of the substrate stable, ensures a stable ultrasonic effect during the deposition process, prevents deformation and cracks caused by overheating, and also helps to increase the cooling rate of the deposited layer, thereby obtaining a finer grain structure. Prepare equipment and ensure that the laser, ultrasound and Ti60 powder converge at the same focus (molten pool) of the substrate to improve the accuracy and efficiency of deposition. Forming a stable molten pool is the key to obtaining a high-quality deposited layer. By controlling the movement of the laser cladding head, single-pass, multi-pass and multi-layer deposition is implemented according to specific forming requirements to achieve a uniform and continuous deposition process. Through precise control of the entire process, Ti60 tissue regulation based on ultrasonic energy field-assisted laser direct energy deposition is successfully realized, and a deposited layer with excellent organization and performance is obtained. The method can effectively ensure the stability of the ultrasonic energy field during the deposition process, and the Ti60 prepared by the method has a more uniform and fine equiaxed crystal structure. The invention has strong operability and applicability. In the actual application process, different laser and ultrasonic process matching parameters can be selected according to the specific forming requirements of different metal parts.

[0017] Furthermore, the ultrasonic energy controller is adjusted to make the amplitude on the substrate surface meet the experimental requirements. The cavitation effect and acoustic streaming effect generated by ultrasound in the molten pool can refine the grains, reduce segregation, promote uniform distribution of elements, etc., thereby significantly improving the structure and performance of the deposited layer.

[0018] Furthermore, Ti60 powder is prepared by a plasma rotating electrode method, which can produce Ti60 powder with high sphericity, uniform particle size distribution and high purity, which is beneficial to improving the quality and performance of the deposited layer.

[0019] Furthermore, the Ti60 powder used in the present invention is a spherical powder of Ti60 titanium alloy, and its powder particle size range is 53~150 μm, which can ensure good fluidity and uniform distribution of the powder during the laser cladding process, avoid powder agglomeration or clogging, and is also conducive to obtaining a dense deposition layer.

[0020] Furthermore, drying at 80-150 °C for 2-3 h can fully remove the water and moisture in the Ti60 powder, preventing defects such as pores from being generated during the laser cladding process, while also not destroying the original properties of the Ti60 powder due to over-drying.

[0021] Furthermore, 500-1000 mesh sandpaper can carefully remove the oxide layer and impurities on the substrate surface, while alcohol cleaning can further ensure the cleanliness of the substrate surface and provide good interface conditions for the deposition process.

[0022] Furthermore, the surface amplitude of the substrate reaching a resonant state is adjusted in the range of 0 to 9 μm, and the intensity of the ultrasonic energy field acting on the substrate can be adjusted according to actual needs, thereby optimizing the metallurgical behavior of the molten pool and the quality of the deposited layer.

[0023] Furthermore, the filling of thermal conductive adhesive can improve the heat conduction efficiency between the water cooling device and the substrate, so that the substrate can dissipate heat faster during the laser cladding process, thereby ensuring the stability of the resonant frequency and providing a more stable ultrasonic effect for the deposition process.

[0024] Furthermore, the powder-carrying gas stably transports the Ti60 powder into the laser molten pool, ensuring the uniform distribution and effective utilization of the Ti60 powder. The protective gas prevents the alloy from being oxidized and contaminated by inclusions during the forming process, and prevents the molten pool from reacting with oxygen, nitrogen, etc. in the air under the action of the laser to produce defects such as oxidation, nitridation and inclusions, thereby protecting the quality and performance of the deposited layer. High-purity argon or high-purity helium as a powder-carrying gas can ensure the stability and purity of the Ti60 powder during the transportation process and avoid the introduction of impurities. High-purity argon or high-purity helium as a protective gas can effectively prevent the molten pool from reacting with oxygen and nitrogen in the air under the action of the laser, thereby protecting the quality and performance of the deposited layer.

[0025] Furthermore, the power of 600~800 W can provide good energy input, so that the Ti60 powder can be fully melted and form a good metallurgical bond with the substrate. The scanning speed of 8~12 mm / s can ensure the deposition efficiency while maintaining the stability of the molten pool. The spot diameter of 3~5 mm can ensure that the laser energy is evenly distributed over a large range, making the molten pool more uniform and the quality of the deposited layer higher. The overlap rate of 50%~70% can ensure good bonding between adjacent tracks and avoid cracks or unfused areas. At the same time, appropriate overlap can also improve the overall density and mechanical properties of the deposited layer. The lift of 0.1~0.2 mm can ensure good bonding between layers while ensuring deposition efficiency and avoid unfused areas.

[0026] Furthermore, an ultrasonic energy field assisted laser direct energy deposition device is used to control the organization of Ti60. The ultrasonic energy field assisted laser direct energy deposition device can introduce a stable ultrasonic energy field during the LDED forming process, and change the solidification process of the molten pool through the cavitation effect and acoustic streaming effect generated by ultrasound in the molten pool. By using an ultrasonic energy field assisted laser direct energy deposition device to control the organization of Ti60, the grain structure of Ti60 can be refined without any post-processing, and more excellent service performance can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the implementation principle of the ultrasonic energy field assisted laser direct energy deposition device of the present invention; Figure 2 The Ti60 grain organization diagram with and without ultrasonic energy field assisted laser direct energy deposition according to the present invention; wherein (a) is without ultrasonic effect; and (b) is with ultrasonic effect.

[0028] Among them: 1. deposited multilayer metal; 2. molten pool; 3. laser; 4. powder feeding nozzle; 5. Ti60 powder; 61. cooling water inlet; 62. cooling water outlet; 7. cooling pipe; 8. substrate; 9. ultrasonic amplitude transformer; 10. ultrasonic transmitter; 11. ultrasonic energy controller; 12. ammeter; 13. frequency adjustment knob; 14. power adjustment knob; 15. workbench plane. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings: Figure 1The schematic diagram of the implementation principle of the ultrasonic energy field assisted laser direct energy deposition device of the present invention is shown in the figure; it can be seen from the figure that the ultrasonic energy field assisted laser direct energy deposition device can be divided into three parts, namely, the ultrasonic energy field assisted device, the water cooling device and the laser direct energy deposition forming device. First, the ultrasonic energy field assisted device is composed of a substrate 8, an ultrasonic horn 9, an ultrasonic transmitter 10 and an ultrasonic energy controller 11 connected in sequence. The substrate 8, the ultrasonic horn 9 and the ultrasonic transmitter 10 are rigidly connected, and the bottom of the ultrasonic transmitter 10 is fixed on the workbench plane 15. The ultrasonic energy controller 11 controls the ultrasonic frequency output by the ultrasonic transmitter 10 through the frequency adjustment knob 13, and observes the current reading of the ammeter 12 to make the substrate 8 reach a resonant state. The ultrasonic energy controller 11 controls the ultrasonic power output by the ultrasonic transmitter 10 through the power adjustment knob 14, thereby adjusting the surface amplitude of the substrate 8. The amplitude of the surface of the substrate 8 is measured using a micrometer to ensure that the ultrasonic intensity meets the experimental requirements. The water cooling device is a cooling tube 7 wound on the substrate 8, and the thermal conductive glue fills the gap between the cooling tube 7 and the substrate 8. The circulating cooling water flows in from the cooling water inlet 61 and flows out from the cooling water outlet 62. The laser direct energy deposition forming device is composed of a powder feeding nozzle 4, Ti60 powder 5 and a laser 3. The Ti60 powder 5 is ejected from the powder feeding nozzle 4 under the action of the powder-carrying gas, and the laser 3 melts the Ti60 powder 5 and forms a molten pool 2. Then the laser cladding head moves on the surface of the substrate 8 and deposits to obtain a deposited multilayer metal 1. The ultrasonic energy field assisted laser direct energy deposition device generates cavitation effect and acoustic streaming effect in the molten pool 2 by utilizing the resonance characteristics of the substrate 8. The cavitation effect can break the columnar grains generated by solidification in the molten pool 2. The broken columnar crystal fragments are evenly distributed in the molten pool 2 under the action of the acoustic streaming effect and serve as nucleation sites for heterogeneous grains, promoting the growth of equiaxed crystal grains. Through the above-mentioned ultrasonic effect, a Ti60 part with a fine equiaxed crystal structure can be obtained without post-processing.

[0032] Figure 2The figure is a grain structure diagram of Ti60 with or without ultrasonic energy field assisted laser direct energy deposition of the present invention; wherein, (a) is without ultrasonic effect; (b) is with ultrasonic effect; it can be seen from the figure that without ultrasonic effect, Ti60 is composed of coarse columnar crystal structure; in the LDED forming process, due to the ultra-high temperature gradient and ultra-fast cooling rate conditions, Ti60 alloy tends to form coarse columnar crystal structure. This structure usually grows along the direction of fastest heat dissipation, that is, the temperature gradient direction, resulting in a large grain aspect ratio and uneven structure. When the ultrasonic energy field is introduced, the acoustic streaming effect and cavitation effect generated by ultrasound in the molten pool 2 can break the original thermal equilibrium state and promote convection and stirring inside the melt. This dynamic action helps to break the growth conditions of columnar crystals and promote the formation of equiaxed crystals. The grain size of equiaxed crystals is smaller and the distribution is more uniform, which is beneficial to improving the overall performance of the material. The ultrasonic acoustic streaming effect can produce a strong mechanical stirring effect, which intensifies the melt flow in the molten pool 2, thereby reducing the temperature gradient inside the melt and increasing the composition uniformity, which is beneficial to the nucleation and growth of equiaxed crystals. Ultrasound can also produce cavitation effect, that is, tiny bubbles are formed in the melt and quickly collapse. The energy released in this process can promote the nucleation of the melt and increase the number of crystal nuclei. In addition, it can also break the formed columnar grains, thereby achieving the effect of grain refinement. Under the action of ultrasound, the grain structure of Ti60 is effectively refined to form a fine equiaxed crystal structure.

[0033] The present invention discloses a Ti60 tissue control method based on ultrasonic energy field assisted laser direct energy deposition, which includes the following steps: preparing spherical Ti60 powder 5; drying Ti60 powder 5; polishing and cleaning the surface of substrate 8; preparing equipment and turning on ultrasonic energy controller 11 to make substrate 8 reach a resonant state; winding cooling tube 7 on substrate 8 and turning on water cooling device; selecting high-purity argon or high-purity helium as powder carrier gas and protective gas to ensure that laser 3, ultrasound and Ti60 powder 5 converge in the same focal molten pool 2 of substrate 8, turning on Ti60 powder 5 delivery and starting laser 3 for deposition; and closing all equipment after deposition. The method realizes the precise deposition of Ti60 titanium alloy through the auxiliary effect of ultrasonic energy field, and improves the tissue uniformity and mechanical properties of the deposited layer. The resonant state of substrate 8 under ultrasonic action is adjusted by frequency adjustment knob 13 and power adjustment knob 14, and the surface amplitude of substrate 8 is measured by micrometer to ensure that the ultrasonic intensity meets the experimental requirements. The resonant frequency and amplitude of substrate 8 can be accurately controlled, thereby ensuring the stability of ultrasonic energy field and improving deposition effect. The cooling tube 7 is wound on the substrate 8 in multiple layers, and the gap between the cooling tube 7 and the substrate 8 is filled with thermal conductive glue to increase the heat dissipation area. The heat accumulation of the substrate 8 is effectively reduced, the resonant frequency of the substrate 8 is kept stable, and the stability of the ultrasonic action during the deposition process is ensured. Ultrasound produces cavitation effect and acoustic streaming effect in the molten pool 2, regulating the metallurgical behavior of the molten pool 2. The cavitation effect and acoustic streaming effect of ultrasound can refine the grain structure and improve the mechanical properties and corrosion resistance of the deposited layer.

[0034] The present invention discloses a Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition, which specifically includes the following steps: Step 1: Ti60 powder 5 is prepared by a plasma rotating electrode method, and its particle size ranges from 53 to 150 μm. It is dried in a vacuum oven at 80 to 150 °C for 2 to 3 h to remove the absorbed moisture, and after drying, it is cooled to room temperature in the furnace and taken out.

[0035] Step 2: Grind the surface of the substrate 8 with 500-1000 grit sandpaper to remove the oxide layer, then clean it with alcohol and blow it dry to remove residual oil on the surface.

[0036] Step 3: Basis Figure 1Prepare the equipment according to the principle shown. Turn on the ultrasonic energy controller 11. At this time, the ultrasound is output by the ultrasonic transmitter 10 and transmitted to the substrate 8 through the ultrasonic horn 9. Adjust the output frequency by the frequency adjustment knob 13 until the current reading of the ammeter 12 is greater than 1 A. At this time, the substrate 8 reaches a resonant state and undergoes cyclic elastic deformation, and the surface of the substrate 8 produces uniform vibration. Adjust the output power by the power adjustment knob 14 to change the amplitude of the surface of the substrate 8, and use a micrometer to measure the amplitude of the surface of the substrate 8 to ensure that the ultrasonic intensity meets the experimental requirements. In this device, the surface amplitude of the substrate 8 can be freely adjusted in the range of 0~9 μm.

[0037] Step 4: Wrap the cooling tube 7 on the substrate 8 in multiple layers to increase the heat dissipation area, fill the gap between the cooling tube 7 and the substrate 8 with thermal conductive glue to further increase the heat dissipation area, and turn on the water cooling device. The water cooling device includes the cooling tube 7, a condenser connected to the cooling tube 7, and a water pump.

[0038] Step 5: Use high-purity argon with a volume percentage of 99.99% to 99.999% or helium with a volume percentage of 99.99% to 99.999% as the powder carrier gas and shielding gas. Start the shielding gas to prevent oxidation and inclusion contamination of the alloy during the forming process. During the experiment, the oxygen content of the atmosphere in the forming chamber was controlled below 200 ppm.

[0039] Step 6: Ensure that the laser 3, the ultrasound emitted by the ultrasonic transmitter 10 and the Ti60 powder 5 delivered by the powder delivery nozzle 4 converge on the same focal molten pool 2 of the substrate 8. Turn on the Ti60 powder 5 delivery, and set the powder delivery rate to 8-12 g / min. Start the laser 3 to form a stable molten pool 2 on the substrate 8. The parameters of the energy deposition of the laser 3 include: laser power of 600-800 W, scanning speed of 8-12 mm / s, spot diameter of 3-5 mm, overlap rate between adjacent tracks of 50%-70%, and laser cladding head lifting amount of 0.1-0.2 mm.

[0040] Step 7: By controlling the laser cladding head to move in the surface area of ​​the substrate 8, single-pass, multi-pass and multi-layer deposition is performed according to specific forming requirements to obtain deposited multi-layer metal 1 until the part is formed.

[0041] Step 8: After the deposition is completed, the laser 3, ultrasound, the conveying of Ti60 powder 5, water cooling and protective gas are turned off in sequence.

[0042] The cooling tube 7 is made of any one of silica gel, pure copper and stainless steel. The substrate 8 is a solid cylinder, and the material is any one of pure titanium, TC4 titanium alloy and Ti60 titanium alloy.

[0043] The Ti60 powder 5 used in this method is a spherical powder of Ti60 titanium alloy, and its powder particle size ranges from 53 to 150 μm. Before the deposition test, the Ti60 powder 5 needs to be dried to remove the absorbed moisture, and then the Ti60 powder 5 is loaded and the substrate 8 is set. Prepare the equipment and ensure that the laser 3, ultrasound and Ti60 powder 5 converge at the same focus (molten pool 2) of the substrate 8. Adjust the ultrasonic energy controller 11 so that the surface amplitude of the substrate 8 meets the experimental requirements. Start the protective gas to prevent oxidation and inclusion contamination of the alloy during the forming process. Start the Ti60 powder 5 delivery, and start the laser 3 to form a stable molten pool 2 on the substrate 8 at the same time. The process parameters of the laser 3 are determined by the characteristics of the Ti60 powder 5 material and the structural parts. By controlling the movement of the laser cladding head in the surface area of ​​the substrate 8, single-channel, multi-channel and multi-layer deposition are implemented according to the specific forming requirements until the part is formed. After the deposition is completed, the laser 3, ultrasound, Ti60 powder 5 delivery, water cooling and protective gas are turned off in sequence.

[0044] The present invention realizes the function by utilizing the resonant characteristics of the substrate 8 under the action of ultrasound. However, the resonant frequency of the substrate 8 will fluctuate with temperature changes. Therefore, the water cooling device is turned on to eliminate the heat generated during the deposition process, thereby ensuring the stability of the resonant frequency. This measure ensures that a stable ultrasonic action can be maintained during the LDED forming process. This method can effectively ensure the stability of the ultrasonic energy field during the deposition process, and the Ti60 powder 5 prepared by this method has a more uniform and fine equiaxed crystal structure. The present invention realizes LDED forming of parts with uniform equiaxed crystal structure through the action of a stable ultrasonic energy field. Changes in the relevant details such as the application method of the ultrasonic energy field, the ultrasonic frequency and intensity, the form of the heat source of the laser 3, the scanning speed and strategy of the laser 3, and the type of Ti60 powder 5 material are all within the scope of the present invention.

[0045] This method effectively reduces the heat accumulation of the substrate 8 by installing a water cooling device on the substrate 8, so that the resonant frequency of the substrate 8 remains stable, ensuring a stable ultrasonic effect during the deposition process. Ultrasound is used to improve the structure of LDED parts. Through the synergistic effect of the cavitation effect and the acoustic streaming effect generated by ultrasound in the molten pool 2, the metallurgical behavior of the molten pool 2 is regulated to achieve the optimization of the grain structure. Without the action of ultrasound, Ti60 presents a coarse columnar crystal structure; under the action of ultrasound, the device effectively refines the grain structure of Ti60 to form a fine equiaxed crystal structure.

[0046] The method for using the ultrasonic energy field assisted laser direct energy deposition device disclosed in the present invention includes: Ti60 powder 5 is ejected from the powder delivery nozzle 4 along with the powder-carrying gas, the laser 3 melts the Ti60 powder 5 and forms a molten pool 2, and then the laser cladding head moves on the surface of the substrate 8 and deposits to obtain a deposited multilayer metal 1. The circulating cooling water flows in from the cooling water inlet 61 and flows out from the cooling water outlet 62. The cooling pipe 7 and the substrate 8 are connected by thermal conductive glue. The substrate 8, the ultrasonic horn 9 and the ultrasonic transmitter 10 are rigidly connected, and the bottom of the ultrasonic transmitter 10 is fixed on the workbench plane 15. The ultrasonic energy controller 11 controls the ultrasonic frequency output by the ultrasonic transmitter 10 through the frequency adjustment knob 13, so that the current reading of the ammeter 12 is stable at 1~1.5 A. The ultrasonic energy controller 11 controls the ultrasonic power output by the ultrasonic transmitter 10 through the power adjustment knob 14, thereby adjusting the surface amplitude of the substrate 8.

[0047] The present invention has strong operability and applicability. In actual application, different laser and ultrasonic process matching parameters can be selected according to specific forming requirements of different metal parts.

[0048] Example 1 A Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition comprises the following steps: Step 1: Ti60 powder 5 is prepared by plasma rotating electrode method, and its particle size is 53-150 μm. It is dried in a vacuum oven at 80 °C for 3 h to remove the absorbed moisture, and after drying, it is cooled to room temperature in the furnace and taken out.

[0049] Step 2: Grind the surface of the substrate 8 with 500-grit sandpaper to remove the oxide layer, then clean it with alcohol and blow it dry to remove residual oil on the surface.

[0050] Step 3: Turn on the ultrasonic energy controller 11, and the ultrasonic transmitter 10 outputs ultrasound, which is transmitted to the substrate 8 via the ultrasonic horn 9. The output frequency is adjusted by the frequency adjustment knob 13 until the current reading of the ammeter 12 is 1 A. At this time, the substrate 8 reaches a resonant state and undergoes cyclic elastic deformation, and the surface of the substrate 8 produces uniform vibration. The output power is adjusted by the power adjustment knob 14 to change the amplitude of the surface of the substrate 8. The amplitude of the surface of the substrate 8 is measured by a micrometer to be 1 μm to ensure that the ultrasonic intensity meets the experimental requirements.

[0051] Step 4: Wrap the cooling tube 7 on the substrate 8 in multiple layers to increase the heat dissipation area, fill the gap between the cooling tube 7 and the substrate 8 with thermal conductive glue to further increase the heat dissipation area, and start the water cooling device.

[0052] Step 5: Select high-purity argon as the powder carrier gas and shielding gas. Start the argon shielding gas to prevent oxidation and inclusion contamination of the alloy during the forming process. During the experiment, the oxygen content in the forming chamber was controlled at 200 ppm.

[0053] Step 6: Ensure that the laser 3, the ultrasound emitted by the ultrasonic transmitter 10 and the Ti60 powder 5 delivered by the powder delivery nozzle 4 converge on the same focal molten pool 2 of the substrate 8. Turn on the Ti60 powder 5 delivery, and set the powder delivery rate to 8 g / min. Start the laser 3 to form a stable molten pool 2 on the substrate 8. The parameters of the energy deposition of the laser 3 include: laser power 600 W, scanning speed 8 mm / s, spot diameter 3 mm, overlap rate between adjacent tracks 50%, and laser cladding head lifting amount 0.1 mm.

[0054] Step 7: By controlling the laser cladding head to move in the surface area of ​​the substrate 8, single-pass, multi-pass and multi-layer deposition is performed according to specific forming requirements to obtain deposited multi-layer metal 1 until the part is formed.

[0055] Step 8: After the deposition is completed, the laser 3, ultrasound, the conveying of Ti60 powder 5, water cooling and protective gas are turned off in sequence.

[0056] Example 2 A Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition comprises the following steps: Step 1: Ti60 powder 5 is prepared by a plasma rotating electrode method, and its particle size is 53-150 μm. It is dried in a vacuum oven at 150 °C for 2 h to remove the absorbed moisture, and after drying, it is cooled to room temperature in the furnace and then taken out.

[0057] Step 2: Grind the surface of the substrate 8 with 1000-grit sandpaper to remove the oxide layer, then clean it with alcohol and blow it dry to remove residual oil on the surface.

[0058] Step 3: Turn on the ultrasonic energy controller 11, and the ultrasonic transmitter 10 outputs ultrasound, which is transmitted to the substrate 8 via the ultrasonic horn 9. The output frequency is adjusted by the frequency adjustment knob 13 until the current reading of the ammeter 12 is 1.5 A. At this time, the substrate 8 reaches a resonant state and undergoes cyclic elastic deformation, and the surface of the substrate 8 produces uniform vibration. The output power is adjusted by the power adjustment knob 14 to change the amplitude of the surface of the substrate 8. The amplitude of the surface of the substrate 8 is measured by a micrometer to be 9 μm to ensure that the ultrasonic intensity meets the experimental requirements.

[0059] Step 4: Wrap the cooling tube 7 on the substrate 8 in multiple layers to increase the heat dissipation area, fill the gap between the cooling tube 7 and the substrate 8 with thermal conductive glue to further increase the heat dissipation area, and start the water cooling device.

[0060] Step 5: Select high-purity helium as the powder carrier gas and shielding gas. Start the helium shielding gas to prevent oxidation and inclusion contamination of the alloy during the forming process. During the experiment, the oxygen content in the forming chamber was controlled at 150 ppm.

[0061] Step 6: Ensure that the laser 3, the ultrasound emitted by the ultrasonic transmitter 10 and the Ti60 powder 5 delivered by the powder delivery nozzle 4 converge on the same focal molten pool 2 of the substrate 8. Turn on the Ti60 powder 5 delivery, and set the powder delivery rate to 12 g / min. Start the laser 3 to form a stable molten pool 2 on the substrate 8. The parameters of the energy deposition of the laser 3 include: laser power 800 W, scanning speed 12 mm / s, spot diameter 5 mm, overlap rate between adjacent tracks 60%, and laser cladding head lift 0.15 mm.

[0062] Step 7: By controlling the laser cladding head to move in the surface area of ​​the substrate 8, single-pass, multi-pass and multi-layer deposition is performed according to specific forming requirements to obtain deposited multi-layer metal 1 until the part is formed.

[0063] Step 8: After the deposition is completed, the laser 3, ultrasound, the conveying of Ti60 powder 5, water cooling and protective gas are turned off in sequence.

[0064] Example 3 A Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition comprises the following steps: Step 1: Ti60 powder 5 is prepared by a plasma rotating electrode method, and its particle size is 53-150 μm. It is dried in a vacuum oven at 120 °C for 2.5 h to remove the absorbed moisture, and after drying, it is cooled to room temperature in the furnace and taken out.

[0065] Step 2: Grind the surface of the substrate 8 with 800-grit sandpaper to remove the oxide layer, then clean it with alcohol and blow it dry to remove residual oil on the surface.

[0066] Step 3: Turn on the ultrasonic energy controller 11, and the ultrasonic transmitter 10 outputs ultrasound, which is transmitted to the substrate 8 via the ultrasonic horn 9. The output frequency is adjusted by the frequency adjustment knob 13 until the current reading of the ammeter 12 is 1.2 A. At this time, the substrate 8 reaches a resonant state and undergoes cyclic elastic deformation, and uniform vibration occurs on the surface of the substrate 8. The output power is adjusted by the power adjustment knob 14 to change the amplitude of the surface of the substrate 8. The amplitude of the surface of the substrate 8 is measured by a micrometer to be 3 μm to ensure that the ultrasonic intensity meets the experimental requirements.

[0067] Step 4: Wrap the cooling tube 7 on the substrate 8 in multiple layers to increase the heat dissipation area, fill the gap between the cooling tube 7 and the substrate 8 with thermal conductive glue to further increase the heat dissipation area, and start the water cooling device.

[0068] Step 5: Select high-purity argon as the powder carrier gas and shielding gas. Start the argon shielding gas to prevent oxidation and inclusion contamination of the alloy during the forming process. During the experiment, the oxygen content in the forming chamber was controlled at 100 ppm.

[0069] Step 6: Ensure that the laser 3, the ultrasound emitted by the ultrasonic transmitter 10 and the Ti60 powder 5 delivered by the powder delivery nozzle 4 converge on the same focal molten pool 2 of the substrate 8. Turn on the Ti60 powder 5 delivery, and set the powder delivery rate to 10 g / min. Start the laser 3 to form a stable molten pool 2 on the substrate 8. The parameters of the energy deposition of the laser 3 include: laser power 700 W, scanning speed 10 mm / s, spot diameter 3 mm, overlap rate between adjacent tracks 70%, and laser cladding head lift 0.2 mm.

[0070] Step 7: By controlling the laser cladding head to move in the surface area of ​​the substrate 8, single-pass, multi-pass and multi-layer deposition is performed according to specific forming requirements to obtain deposited multi-layer metal 1 until the part is formed.

[0071] Step 8: After the deposition is completed, the laser 3, ultrasound, the conveying of Ti60 powder 5, water cooling and protective gas are turned off in sequence.

[0072] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition, characterized in that: An ultrasonic energy field assisted laser direct energy deposition device is used to perform Ti60 tissue regulation; the ultrasonic energy field assisted laser direct energy deposition device comprises a laser direct energy deposition forming device, a water cooling device and an ultrasonic energy field assisted device which are connected in sequence; the laser direct energy deposition forming device provides laser light (3); the ultrasonic energy field assisted device comprises a substrate (8) and an ultrasonic component connected to the substrate (8); the method comprises: Step 1: Drying the Ti60 powder (5); Step 2: polishing and cleaning the surface of the substrate (8); Step 3: Turn on the ultrasound through the ultrasonic component, and adjust the frequency and power to make the substrate (8) reach a resonant state; Step 4: Turn on the water cooling device wound on the base plate (8); Step 5: introducing powder-carrying gas and protective gas; Step 6: After ensuring that the laser (3), ultrasound and Ti60 powder (5) converge at the same focal point of the substrate (8); conveying Ti60 powder (5), starting the laser (3), forming a stable molten pool (2) on the substrate (8), and controlling the movement of the laser cladding head on the surface of the substrate (8) to perform deposition to obtain deposited multilayer metals (1), and regulating the metallurgical behavior of the molten pool (2) through the cavitation effect and acoustic streaming effect generated by ultrasound in the molten pool (2); Step 7: After the deposition is completed, the laser (3) and ultrasound are turned off in sequence, the delivery of Ti60 powder (5) is stopped, the water cooling device and the protective gas are turned off, and a Ti60 part with a fine equiaxed crystal structure is obtained.

2. The Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition according to claim 1 is characterized in that: In step 1, the Ti60 powder (5) is prepared by a plasma rotating electrode method.

3. The Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition according to claim 1, characterized in that: In step 1, the particle size of the Ti60 powder (5) is in the range of 53-150 μm.

4. The Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition according to claim 1, characterized in that: In step 1, the drying condition is: drying at 80-150°C for 2-3 hours.

5. The Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition according to claim 1 is characterized in that: In step 2, use 500~1000 grit sandpaper for polishing; use alcohol for cleaning.

6. The Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition according to claim 1, characterized in that: In step 3, the surface amplitude of the substrate (8) reaching a resonant state is adjusted within a range of 0 to 9 μm.

7. The Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition according to claim 1 is characterized in that: In step 4, heat-conducting glue is filled between the water cooling device and the substrate (8).

8. The Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition according to claim 1 is characterized in that: In step 5, the powder-carrying gas is argon or helium; and the protective gas is argon or helium.

9. The Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition according to claim 1, characterized in that: In step 6, the powder feeding rate of the Ti60 powder (5) is 8-12 g / min; the energy deposition parameters of the laser (3) include: laser power of 600-800 W, scanning speed of 8-12 mm / s, spot diameter of 3-5 mm, overlap rate between adjacent tracks of 50%-70%, and laser cladding head lifting amount of 0.1-0.2 mm.

10. The Ti60 tissue regulation method based on ultrasonic energy field assisted laser direct energy deposition according to claim 1, characterized in that: The laser direct energy deposition forming device further comprises a powder delivery nozzle (4) for delivering Ti60 powder (5); The laser (3) melts the Ti60 powder (5) to form a molten pool (2) on the surface of the substrate (8); the laser (3), ultrasound and the Ti60 powder (5) converge in the molten pool (2); The water cooling device is a cooling pipe (7) wound on a base plate (8); The ultrasonic component comprises an ultrasonic horn (9), an ultrasonic transmitter (10) and an ultrasonic energy controller (11) which are sequentially connected to the base plate (8).

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