A Method for Controlling the Microstructure of Ti60 Based on Ultrasonic Energy Field Assisted Laser Direct Energy Deposition

Abstract

The present invention discloses a method for regulating the microstructure of Ti60 based on ultrasonic energy field-assisted laser direct energy deposition, belonging to the technical field of metal additive manufacturing. The method includes: drying the Ti60 powder; grinding and cleaning the surface of the substrate; turning on the ultrasonic wave through the ultrasonic component, adjusting the frequency and power to make the substrate reach the resonant state; turning on the water cooling device; introducing the powder-carrying gas and the protective gas; after ensuring that the laser, the ultrasonic wave and the Ti60 powder converge at the same focal point on the substrate; conveying the Ti60 powder, starting the laser, forming a stable molten pool on the substrate, after the deposition is completed, turning off the laser and the ultrasonic wave in sequence, stopping the conveying of the Ti60 powder, turning off the water cooling device and the protective gas, and obtaining a Ti60 part with a fine equiaxed crystal structure. The water cooling device eliminates heat accumulation, ensures the stability of the resonant frequency of the substrate, and realizes the stable ultrasonic effect; through the cavitation effect and the acoustic streaming effect generated by the ultrasonic wave in the molten pool, the metallurgical behavior of the molten pool is regulated to realize the refinement and regulation of the grain structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal additive manufacturing, and particularly relates to a method for regulating the microstructure of Ti60 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 aero-engines are increasing day by day. Among them, the thrust-to-weight ratio, as one of the key indicators for measuring the performance of an engine, its continuous improvement has directly promoted the innovation of aero-engine design and manufacturing technologies. In this process, as the core component of an aero-engine, the continuous increase in the outlet temperature of the compressor poses a more severe challenge to the high-temperature performance of materials. Although traditional superalloys meet the usage 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, more excellent thermal stability, and lighter weight have become the key factors to promote the progress of aero-engine technology. Near-α titanium alloys, especially high-performance titanium alloys such as Ti60, are regarded as important material choices to replace some traditional superalloys and achieve the lightweight of aircraft due to their unique thermal strength and thermal stability, as well as their long-term working ability at 600 °C or even higher temperatures. These titanium alloys have shown broad application prospects in the fields of high-temperature components of aero-engines, thermal protection systems of hypersonic aircraft, etc., and are of great significance for improving the overall performance and reliability of aircraft.

[0003] Regarding the additive manufacturing of near-α titanium alloys such as Ti60, the laser direct energy deposition (LDED) technology has received extensive attention in the aerospace field because it can directly perform the integrated forming of complex structures according to the design model. The LDED technology realizes the rapid conversion from design to solid parts through the layer-by-layer and channel-by-channel melting and deposition of powder materials, and is particularly suitable for the large-scale and rapid forming of large structural parts. However, the unique process characteristics such as the rapid cooling of the micro-melting pool, large temperature gradient solidification, and layer-by-layer reciprocating reheating cycle during the LDED process also bring difficulties in tissue control and performance optimization. In order to improve the microstructure of near-α titanium alloys such as Ti60 formed by LDED, researchers have tried various 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 certain results to a certain extent, but there are still problems such as coarse grain structures and obvious mechanical property anisotropy, and the addition of alloying elements may change the composition and performance balance of the original alloy.

[0004] Although the 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 urgently. First, due to the rapid solidification characteristics of the micro-melting pool during the LDED process, large columnar grains that grow epitaxially along the deposition layer are likely to appear inside the parts. This anisotropic tissue characteristic seriously affects the mechanical properties and reliability of the parts. Second, although the tissue can be improved to a certain extent by adjusting process parameters and adding alloying elements, these methods are often accompanied by an increase in process complexity and a change in alloy composition, which not only increases the manufacturing cost but also may introduce new performance uncertainties. In addition, how to effectively refine the tissue and comprehensively improve the mechanical properties while maintaining the original excellent properties of the alloy is still a major technical problem in the field of LDED forming near-α titanium alloys. Therefore, exploring a simple, efficient method that can take into account tissue refinement and performance improvement is of great significance for promoting the application of LDED technology in the additive manufacturing field of high-performance titanium alloys. Summary of the Invention

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

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] The present invention discloses a method for regulating the Ti60 tissue based on ultrasonic energy field-assisted laser direct energy deposition, and uses an ultrasonic energy field-assisted laser direct energy deposition device to regulate the Ti60 tissue; the ultrasonic energy field-assisted laser direct energy deposition device includes a laser direct energy deposition forming device, a water cooling device, and an ultrasonic energy field assisting device connected in sequence; the laser direct energy deposition forming device provides laser; the ultrasonic energy field assisting device includes a substrate and an ultrasonic component connected to the substrate; the method includes:

[0008] Step 1: Dry the Ti60 powder.

[0009] Step 2: Grind and clean the surface of the substrate.

[0010] Step 3: Turn on the ultrasonic through the ultrasonic component, and adjust the frequency and power to make the substrate reach the resonant state.

[0011] Step 4: Turn on the water cooling device wound on the substrate.

[0012] Step 5: Introduce the powder-carrying gas and the protective gas.

[0013] Step 6: After ensuring that the laser, ultrasound, and Ti60 powder converge at the same focal point on the substrate; convey the Ti60 powder, start the laser, form a stable molten pool on the substrate, control the movement of the laser cladding head on the substrate surface, and perform deposition to obtain the deposited multi-layer metal. Regulate the metallurgical behavior of the molten pool through the cavitation effect and acoustic streaming effect generated by ultrasound in the molten pool;

[0014] Step 7: After the deposition is completed, turn off the laser and ultrasound in sequence, stop conveying the Ti60 powder, turn off the water cooling device and the protective gas, and obtain a Ti60 part with a fine equiaxed crystal structure.

[0015] Preferably, in Step 1, the Ti60 powder is prepared by the plasma rotating electrode process.

[0016] Preferably, in Step 1, the particle size range of the Ti60 powder is 53 - 150 μm.

[0017] Preferably, in Step 1, the conditions for the drying treatment are: drying at 80 - 150 °C for 2 - 3 h.

[0018] Preferably, in Step 2, sandpaper with 500 - 1000 meshes is used for grinding; alcohol is used for cleaning.

[0019] Preferably, in Step 3, the surface amplitude of the substrate reaching the resonant state is adjusted within the range of 0 - 9 μm.

[0020] Preferably, in Step 4, a thermal conductive adhesive is filled between the water cooling device and the substrate.

[0021] Preferably, in Step 5, the powder-carrying gas is argon or helium; the protective gas is argon or helium.

[0022] Preferably, in Step 6, the powder feeding rate of the 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 the laser cladding head of 0.1 - 0.2 mm.

[0023] Preferably, the laser direct energy deposition forming device further includes a powder feeding nozzle for conveying the Ti60 powder;

[0024] The laser melts the Ti60 powder to form a molten pool on the substrate surface; the laser, ultrasound, and Ti60 powder converge at the molten pool;

[0025] The water cooling device is a cooling pipe wound around the substrate;

[0026] The ultrasonic component includes an ultrasonic horn, an ultrasonic emitter, and an ultrasonic energy controller that are sequentially connected to a substrate.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention discloses a method for regulating the microstructure of Ti60 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 defects such as pores from being generated during the laser cladding process, improve the density and mechanical properties of the deposited layer, and ensure that the used Ti60 powder has a consistent composition and particle size distribution, which is the basis for obtaining a high-quality deposited layer, and the loading and substrate setting are completed. The oxide layer, oil stain, and other impurities on the surface of the substrate are removed by grinding to improve the bonding strength between the substrate and the deposited layer. Cleaning further ensures the cleanliness of the substrate surface, reduces the presence of contaminants, and provides good interfacial conditions for the subsequent deposition process. An ultrasonic energy field is introduced to provide assistance for the subsequent laser cladding process. By precisely adjusting the frequency and power of the ultrasonic wave, the substrate reaches the resonant state, which helps to generate stronger cavitation effects and acoustic streaming effects in the molten pool, thereby optimizing the metallurgical behavior of the molten pool. The present invention realizes its function by utilizing the resonant characteristics of the substrate under the action of ultrasonic waves. However, the resonant frequency of the substrate will fluctuate with temperature changes. During the laser cladding process, the substrate will be subjected to high temperatures. 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 action can be maintained during the LDED forming process; effectively reduces the heat accumulation of the substrate and keeps the resonant frequency of the substrate stable, ensuring a stable ultrasonic action effect during the deposition process, preventing deformation and cracks caused by overheating, and also helps to increase the cooling rate of the deposited layer, thereby obtaining a finer grain microstructure. Prepare the equipment and ensure that the laser, ultrasonic wave, and Ti60 powder converge at the same focus (molten pool) of the substrate to improve the deposition accuracy and efficiency. Forming a stable molten pool is the key to obtaining a high-quality deposited layer. By controlling the movement of the laser cladding head and implementing single-pass, multi-pass, and multi-layer depositions according to specific forming requirements, a uniform and continuous deposition process is achieved. Through the precise control of the entire process, the regulation of the microstructure of Ti60 based on ultrasonic energy field-assisted laser direct energy deposition is successfully realized, and a deposited layer with excellent microstructure and properties is obtained. This method can effectively ensure the stability of the ultrasonic energy field during the deposition process, and at the same time, the Ti60 prepared by this method has a more uniform and finer equiaxed crystal microstructure. The present invention has strong operability and applicability. During the actual application process, different laser and ultrasonic process matching parameters can be selected according to the specific forming requirements of different metal parts.

[0029] Furthermore, adjust the ultrasonic energy controller 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 grains, reduce segregation, and promote uniform distribution of elements, etc., thus significantly improving the microstructure and properties of the deposited layer.

[0030] Furthermore, the Ti60 powder is prepared by the plasma rotating electrode method, which can produce Ti60 powder with high sphericity, uniform particle size distribution, and high purity, facilitating the improvement of the quality and properties of the deposited layer.

[0031] Furthermore, the Ti60 powder used in the present invention is spherical Ti60 titanium alloy powder, 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 deposited layer.

[0032] Furthermore, drying at 80 - 150 °C for 2 - 3 h can fully remove the moisture and humidity in the Ti60 powder, prevent defects such as pores from occurring during the laser cladding process, and will not damage the original properties of the Ti60 powder due to over - drying.

[0033] 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, providing good interfacial conditions for the deposition process.

[0034] Furthermore, the surface amplitude of the substrate reaching the resonant state is adjusted within the range of 0 - 9 μm, and the action intensity of the ultrasonic energy field 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.

[0035] Furthermore, the filling of thermal conductive adhesive can improve the heat conduction efficiency between the water - cooling device and the substrate, enabling the substrate to dissipate heat faster during the laser cladding process, thus ensuring the stability of the resonant frequency and providing a more stable ultrasonic action effect for the deposition process.

[0036] Furthermore, the powder - carrying gas stably transports the Ti60 powder to the laser molten pool, ensuring the uniform distribution and effective utilization of the Ti60 powder. The protective gas prevents oxidation and inclusion contamination of the alloy during the forming process, prevents the molten pool from reacting with oxygen, nitrogen, etc. in the air under the action of the laser, generating defects such as oxidation, nitridation, and inclusions, and protects the quality and properties of the deposited layer. High - purity argon or high - purity helium as the powder - carrying gas can ensure the stability and purity of the Ti60 powder during transportation, avoiding the introduction of impurities. High - purity argon or high - purity helium as the protective gas can effectively prevent the molten pool from reacting with oxygen and nitrogen, etc. in the air under the action of the laser, protecting the quality and properties of the deposited layer.

[0037] Furthermore, a power of 600 - 800 W can provide good energy input, enabling the Ti60 powder to fully melt and form a good metallurgical bond with the substrate. A scanning speed of 8 - 12 mm / s, while maintaining the stability of the molten pool, also ensures the deposition efficiency. A spot diameter of 3 - 5 mm can ensure uniform distribution of laser energy over a large area, making the molten pool more uniform and the quality of the deposited layer higher. An overlap rate of 50% - 70% can ensure good bonding between adjacent tracks, avoiding the generation of cracks or unfused regions. At the same time, appropriate overlap can also improve the overall density and mechanical properties of the deposited layer. A lift of 0.1 - 0.2 mm can ensure good bonding between layers while guaranteeing the deposition efficiency, avoiding the generation of unfused regions.

[0038] Furthermore, an ultrasonic energy field-assisted laser direct energy deposition device is used for Ti60 microstructure control. This 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 the ultrasonic energy field-assisted laser direct energy deposition device for Ti60 microstructure control, the grain structure of Ti60 can be refined without any post-treatment, obtaining more excellent service performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is the implementation schematic diagram of the ultrasonic energy field-assisted laser direct energy deposition device of the present invention;

[0040] Figure 2 is the grain structure diagram of laser direct energy deposition of Ti60 with and without ultrasonic energy field assistance of the present invention; among them, (a) is without ultrasonic action; (b) is with ultrasonic action.

[0041] Wherein: 1. Deposited multi-layer 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 horn; 10. Ultrasonic transmitter; 11. Ultrasonic energy controller; 12. Ammeter; 13. Frequency adjustment knob; 14. Power adjustment knob; 15. Workbench plane. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0043] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0044] The present invention will be further described in detail below with reference to the drawings:

[0045] Figure 1This is the implementation schematic diagram of the ultrasonic energy field assisted laser direct energy deposition device of the present invention; 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 consists of a substrate 8, an ultrasonic horn 9, an ultrasonic emitter 10, and an ultrasonic energy controller 11 connected in sequence. The substrate 8, the ultrasonic horn 9, and the ultrasonic emitter 10 are rigidly connected to each other, and the bottom of the ultrasonic emitter 10 is fixed on the workbench plane 15. The ultrasonic energy controller 11 controls the ultrasonic frequency output by the ultrasonic emitter 10 through the frequency adjustment knob 13, and observes the current indication of the ammeter 12 to make the substrate 8 reach the resonant state. The ultrasonic energy controller 11 controls the ultrasonic power output by the ultrasonic emitter 10 through the power adjustment knob 14, thereby adjusting the surface amplitude of the substrate 8. A dial indicator is used to measure the amplitude of the substrate 8 surface to ensure that the ultrasonic intensity meets the experimental requirements. The water cooling device is a cooling pipe 7 wound around the substrate 8, and thermal conductive glue is filled in the gap between the cooling pipe 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 consists 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. The laser 3 melts the Ti60 powder 5 to form a molten pool 2. Subsequently, the laser cladding head moves on the surface of the substrate 8 and deposits to obtain the deposited multi-layer metal 1. The ultrasonic energy field assisted laser direct energy deposition device utilizes the resonant characteristics of the substrate 8 to generate cavitation effects and acoustic streaming effects in the molten pool 2. 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 heterogeneous grain nucleation sites to promote the growth of equiaxed grains. Through the above ultrasonic action effects, Ti60 parts with fine equiaxed grain structures can be obtained without post-treatment.

[0046] Figure 2The grain microstructure diagrams of Ti60 with and without ultrasonic energy field assistance for the present invention; among them, (a) is without ultrasonic action; (b) is with ultrasonic action; it can be seen from the figure that without ultrasonic action, Ti60 is composed of coarse columnar crystal structures; during the LDED forming process, due to the ultra-high temperature gradient and ultra-fast cooling rate conditions, the Ti60 alloy tends to form coarse columnar crystal structures. This kind of structure usually grows along the direction with the fastest heat dissipation, that is, the temperature gradient direction, resulting in a large aspect ratio of grains and uneven structure. When introducing the ultrasonic energy field, the acoustic streaming effect and cavitation effect generated by the ultrasonic in the molten pool 2 can break the original thermal equilibrium state and promote the convection and stirring inside the melt. This dynamic effect 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 acoustic streaming effect of the ultrasonic can produce a strong mechanical stirring effect, intensifying the melt flow in the molten pool 2, thereby reducing the temperature gradient inside the melt and increasing the compositional uniformity, which is beneficial to the nucleation and growth of equiaxed crystals. The ultrasonic can also generate a cavitation effect, that is, forming tiny bubbles in the melt and quickly collapsing. The energy released during this process can promote the nucleation of the melt, increase the number of crystal nuclei, and in addition, can break the formed columnar grains, thus achieving the effect of grain refinement. Under the action of the ultrasonic, the grain microstructure of Ti60 is effectively refined to form fine equiaxed crystal structures.

[0047] A method for controlling the microstructure of Ti60 based on ultrasonic energy field assisted laser direct energy deposition disclosed by the present invention includes: preparing spherical Ti60 powder 5; drying the Ti60 powder 5; polishing and cleaning the surface of the substrate 8; preparing the equipment and turning on the ultrasonic energy controller 11 to make the substrate 8 reach the resonant state; winding the cooling pipe 7 on the substrate 8 and turning on the water cooling device; selecting high-purity argon or high-purity helium as the powder-carrying gas and the shielding gas to ensure that the laser 3, the ultrasonic wave, and the Ti60 powder 5 converge at the same focal point molten pool 2 on the substrate 8, turning on the delivery of the Ti60 powder 5 and starting the laser 3 for deposition; and turning off all the equipment after the deposition. Through the auxiliary action of the ultrasonic energy field, this method realizes the precise deposition of the Ti60 titanium alloy, and improves the microstructure uniformity and mechanical properties of the deposited layer. The resonant state of the substrate 8 under the action of the ultrasonic wave is adjusted by the frequency adjustment knob 13 and the power adjustment knob 14, and a dial indicator is used to measure the amplitude of the surface of the substrate 8 to ensure that the ultrasonic intensity meets the experimental requirements. The resonant frequency and amplitude of the substrate 8 can be precisely controlled, thereby ensuring the stability of the ultrasonic energy field and improving the deposition effect. The cooling pipe 7 is wound around the substrate 8 in multiple layers, and the gap between the cooling pipe 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. The ultrasonic wave generates cavitation effect and acoustic streaming effect in the molten pool 2 to regulate the metallurgical behavior of the molten pool 2. The cavitation effect and acoustic streaming effect of the ultrasonic wave can refine the grain structure and improve the mechanical properties and corrosion resistance of the deposited layer.

[0048] A method for controlling the microstructure of Ti60 based on ultrasonic energy field assisted laser direct energy deposition disclosed by the present invention specifically includes the following steps:

[0049] Step 1: The Ti60 powder 5 is prepared by the plasma rotating electrode method, and its particle size range is 53 - 150 μm. It is dried in a vacuum drying oven at 80 - 150 °C for 2 - 3 h to remove the absorbed moisture, and after drying, it is cooled to room temperature in the furnace and then taken out.

[0050] Step 2: The surface of the substrate 8 is polished with 500 - 1000 mesh sandpaper to remove the oxide layer, and then washed and dried with alcohol to remove the residual oil stains on the surface.

[0051] Step 3: According to Figure 1Prepare the equipment according to the principle shown. Turn on the ultrasonic energy controller 11. At this time, ultrasonic waves are output from the ultrasonic emitter 10 and transmitted to the inside of the substrate 8 through the ultrasonic horn 9. Adjust the output frequency through 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 the resonance state and undergoes cyclic elastic deformation, and uniform vibrations are generated on the surface of the substrate 8. Adjust the output power through 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 amplitude of the surface of the substrate 8 can be freely adjusted within the range of 0 - 9 μm.

[0052] Step 4: Wind the cooling tube 7 around the substrate 8 in multiple layers to increase the heat dissipation area, and fill the gap between the cooling tube 7 and the substrate 8 with thermal conductive glue to further increase the heat dissipation area, then turn on the water cooling device. The water cooling device includes the cooling tube 7, a condenser and a water pump connected to the cooling tube 7.

[0053] Step 5: Select high-purity argon with a volume percentage of 99.99% - 99.999% or helium with a volume percentage of 99.99% - 99.999% as the powder-carrying gas and the protective gas. Start the protective gas to prevent oxidation and inclusion contamination of the alloy during the forming process. During the experiment, the oxygen content in the atmosphere inside the forming chamber is controlled below 200 ppm.

[0054] Step 6: Ensure that the laser 3, the ultrasonic waves emitted by the ultrasonic emitter 10, and the Ti60 powder 5 sent out by the powder feeding nozzle 4 converge at the same focal point molten pool 2 on the substrate 8. Turn on the delivery of the Ti60 powder 5, and set the powder feeding amount 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 is 600 - 800 W, scanning speed is 8 - 12 mm / s, spot diameter is 3 - 5 mm, the overlap rate between adjacent tracks is 50% - 70%, and the lifting amount of the laser cladding head is 0.1 - 0.2 mm.

[0055] Step 7: Control the movement of the laser cladding head within the surface area of the substrate 8, and perform single-pass, multi-pass and multi-layer deposition according to specific forming requirements to obtain the deposited multi-layer metal 1 until the part forming is completed.

[0056] Step 8: After the deposition is completed, turn off the laser 3, ultrasonic waves, the delivery of the Ti60 powder 5, water cooling and the protective gas in sequence.

[0057] The material of the cooling tube 7 includes any one of silicone, pure copper and stainless steel. The substrate 8 is a solid cylinder, and the material includes any one of pure titanium, TC4 titanium alloy and Ti60 titanium alloy.

[0058] The Ti60 powder 5 used in this method is spherical powder of Ti60 titanium alloy, and the powder particle size range is 53 - 150 μm. Before the deposition test, the Ti60 powder 5 needs to be dried to remove the absorbed moisture, and then the loading of the Ti60 powder 5 and the setting of the substrate 8 are completed. 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 to make the surface amplitude of the substrate 8 reach the experimental requirements. Start the protective gas to prevent oxidation and inclusion contamination of the alloy during the forming process. Start the delivery of the Ti60 powder 5, and at the same time start the laser 3 to form a stable molten pool 2 on the substrate 8. The process parameters of the laser 3 are determined by the characteristics and structural parts of the Ti60 powder 5 material. By controlling the movement of the laser cladding head within the surface area of the substrate 8, single-pass, multi-pass, and multi-layer depositions are carried out according to specific forming requirements until the part forming is completed. After the deposition is completed, turn off the laser 3, ultrasound, Ti60 powder 5 delivery, water cooling, and protective gas in sequence.

[0059] The present invention realizes the function by utilizing the resonance characteristics of the substrate 8 under the action of ultrasound. However, the resonance frequency of the substrate 8 will fluctuate with the change of temperature. Therefore, turn on the water cooling device to eliminate the heat generated during the deposition process, so as to ensure the stability of the resonance 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 at the same time, the Ti60 powder 5 prepared by this method has a more uniform and fine equiaxed crystal structure. The present invention realizes the LDED forming of parts with a uniform equiaxed crystal structure through the action of a stable ultrasonic energy field. The changes in relevant details such as the application method of the ultrasonic energy field, the ultrasonic wave 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 the Ti60 powder 5 material are all within the scope of the claims of the present invention.

[0060] This method effectively reduces the heat accumulation of the substrate 8 by installing a water cooling device on the substrate 8, keeps the resonance frequency of the substrate 8 stable, and ensures a stable ultrasonic action effect during the deposition process. Utilize ultrasound 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; while under the action of ultrasound, the device effectively refines the grain structure of Ti60 to form a fine equiaxed crystal structure.

[0061] The usage method of the ultrasonic energy field assisted laser direct energy deposition device disclosed in the present invention includes: Ti60 powder 5 is ejected from the powder feeding nozzle 4 along with the powder carrying gas, the laser 3 melts the Ti60 powder 5 to form a molten pool 2, and then the laser cladding head moves on the surface of the substrate 8 and deposits to obtain the deposited multi-layer 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 is connected to the substrate 8 with thermal conductive adhesive. There is a rigid connection among the substrate 8, the ultrasonic horn 9 and the ultrasonic emitter 10, and the bottom of the ultrasonic emitter 10 is fixed on the workbench plane 15. The ultrasonic energy controller 11 controls the ultrasonic frequency output by the ultrasonic emitter 10 through the frequency adjustment knob 13 to make the current indication of the ammeter 12 stable at 1 - 1.5 A. The ultrasonic energy controller 11 controls the ultrasonic power output by the ultrasonic emitter 10 through the power adjustment knob 14 to adjust the surface amplitude of the substrate 8.

[0062] The present invention has strong operability and applicability. During the actual application process, different lasers 3 and ultrasonic process matching parameters can be selected according to the specific forming requirements of different metal parts.

[0063] Example 1

[0064] A method for regulating the Ti60 microstructure based on ultrasonic energy field assisted laser direct energy deposition includes the following steps:

[0065] Step 1: The Ti60 powder 5 is prepared by the plasma rotating electrode method, and its particle size is 53 - 150 μm. It is dried in a vacuum drying oven at 80 °C for 3 h to remove the absorbed moisture, and after drying, it is taken out after being cooled to room temperature in the furnace.

[0066] Step 2: The surface of the substrate 8 is polished with 500 - mesh sandpaper to remove the oxide layer, and then it is cleaned with alcohol and dried to remove the residual oil stain on the surface.

[0067] Step 3: Turn on the ultrasonic energy controller 11, the ultrasonic emitter 10 outputs ultrasonic waves, and transmits them to the inside of the substrate 8 through the ultrasonic horn 9. Adjust the output frequency through the frequency adjustment knob 13 until the current indication of the ammeter 12 is 1 A. At this time, the substrate 8 reaches the resonance state and undergoes cyclic elastic deformation, and uniform vibration is generated on the surface of the substrate 8. Adjust the output power through the power adjustment knob 14 to change the surface amplitude of the substrate 8, and use a micrometer to measure the surface amplitude of the substrate 8 to be 1 μm to ensure that the ultrasonic intensity meets the experimental requirements.

[0068] Step 4: Wind the cooling pipe 7 around the substrate 8 in multiple layers to increase the heat dissipation area, fill the gap between the cooling pipe 7 and the substrate 8 with thermal conductive adhesive to further increase the heat dissipation area, and turn on the water cooling device.

[0069] Step 5: Select high-purity argon as the powder-carrying gas and the 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 is controlled at 200 ppm.

[0070] Step 6: Ensure that the laser 3, the ultrasound emitted by the ultrasonic emitter 10, and the Ti60 powder 5 delivered by the powder feeder nozzle 4 converge at the same focal point molten pool 2 on the substrate 8. Start the delivery of the Ti60 powder 5, and set the powder feeding 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 lifting amount of the laser cladding head 0.1 mm.

[0071] Step 7: Control the movement of the laser cladding head within the surface area of the substrate 8, and perform single-pass, multi-pass, and multi-layer depositions according to specific forming requirements to obtain the deposited multi-layer metal 1 until the part forming is completed.

[0072] Step 8: After the deposition is completed, turn off the laser 3, ultrasound, the delivery of the Ti60 powder 5, water cooling, and the shielding gas in sequence.

[0073] Example 2

[0074] A method for regulating the microstructure of Ti60 based on ultrasonic energy field-assisted laser direct energy deposition includes the following steps:

[0075] Step 1: The Ti60 powder 5 is prepared by the plasma rotating electrode method, and its particle size is 53 - 150 μm. Dry it in a vacuum drying oven at 150 °C for 2 h to remove the absorbed moisture. After drying, cool it in the furnace to room temperature and then take it out.

[0076] Step 2: Polish the surface of the substrate 8 with 1000-mesh sandpaper to remove the oxide layer, and then clean and dry it with alcohol to remove the residual oil stains on the surface.

[0077] Step 3: Turn on the ultrasonic energy controller 11, output ultrasonic waves from the ultrasonic emitter 10, and transmit them to the inside of the substrate 8 through the ultrasonic horn 9. Adjust the output frequency through the frequency adjustment knob 13 until the current reading of the ammeter 12 is 1.5 A. At this time, the substrate 8 reaches the resonant state and undergoes cyclic elastic deformation, and uniform vibrations are generated on the surface of the substrate 8. Adjust the output power through 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 be 9 μm to ensure that the ultrasonic intensity meets the experimental requirements.

[0078] Step 4: Wind the cooling pipe 7 around the substrate 8 in multiple layers to increase the heat dissipation area, fill the gap between the cooling pipe 7 and the substrate 8 with thermal conductive glue to further increase the heat dissipation area, and turn on the water cooling device.

[0079] Step 5: Select high-purity helium as the powder-carrying gas and the protective gas. Start the helium protective gas to prevent oxidation and inclusion contamination of the alloy during the forming process. During the experiment, the oxygen content in the forming chamber is controlled at 150 ppm.

[0080] Step 6: Ensure that the laser 3, the ultrasound emitted by the ultrasonic emitter 10, and the Ti60 powder 5 delivered by the powder feeder nozzle 4 converge at the same focal point molten pool 2 on the substrate 8. Start the delivery of the Ti60 powder 5, and set the powder feeding 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 lifting amount of the laser cladding head 0.15 mm.

[0081] Step 7: Control the movement of the laser cladding head within the surface area of the substrate 8, and perform single-pass, multi-pass, and multi-layer depositions according to specific forming requirements to obtain the deposited multi-layer metal 1 until the part forming is completed.

[0082] Step 8: After the deposition is completed, turn off the laser 3, ultrasound, delivery of the Ti60 powder 5, water cooling, and protective gas in sequence.

[0083] Example 3

[0084] A method for regulating the microstructure of Ti60 based on ultrasonic energy field-assisted laser direct energy deposition, comprising the following steps:

[0085] Step 1: The Ti60 powder 5 is prepared by the plasma rotating electrode method, and its particle size is 53 - 150 μm. It is dried in a vacuum drying 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 then taken out.

[0086] Step 2: Polish the surface of the substrate 8 with 800-mesh sandpaper to remove the oxide layer, and then clean and dry it with alcohol to remove the residual oil stains on the surface.

[0087] Step 3: Turn on the ultrasonic energy controller 11, output ultrasonic waves from the ultrasonic emitter 10, and transmit them to the inside of the substrate 8 through the ultrasonic horn 9. Adjust the output frequency through the frequency adjustment knob 13 until the current reading of the ammeter 12 is 1.2 A. At this time, the substrate 8 reaches the resonant state and undergoes cyclic elastic deformation, and uniform vibrations are generated on the surface of the substrate 8. Adjust the output power through 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 be 3 μm to ensure that the ultrasonic intensity meets the experimental requirements.

[0088] Step 4: Wind the cooling pipe 7 around the substrate 8 in multiple layers to increase the heat dissipation area, fill the gap between the cooling pipe 7 and the substrate 8 with thermal conductive adhesive to further increase the heat dissipation area, and turn on the water cooling device.

[0089] Step 5: Select high-purity argon as the powder-carrying gas and the 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 is controlled at 100 ppm.

[0090] Step 6: Ensure that the laser 3, the ultrasonic wave emitted by the ultrasonic emitter 10, and the Ti60 powder 5 delivered by the powder feeding nozzle 4 converge at the same focal point molten pool 2 on the substrate 8. Turn on the delivery of the Ti60 powder 5, and set the powder feeding 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 lifting amount of the laser cladding head 0.2 mm.

[0091] Step 7: Control the movement of the laser cladding head within the surface area of the substrate 8, and perform single-pass, multi-pass, and multi-layer depositions according to specific forming requirements to obtain the deposited multi-layer metal 1 until the part forming is completed.

[0092] Step 8: After the deposition is completed, turn off the laser 3, ultrasonic wave, delivery of the Ti60 powder 5, water cooling, and shielding gas in sequence.

[0093] The above content is only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls 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 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 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 substrate (8) is a solid cylinder; 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 ultrasound through the ultrasonic component, and adjust the frequency and power so that the substrate (8) reaches a resonant state; the surface amplitude of the substrate (8) reaching the resonant state is adjusted within a range of 0 to 9 μm; Step 4: Turn on the water cooling device wound on the substrate (8); ensure the stability of the resonant frequency; ensure that a stable ultrasonic effect can be maintained during the LDED forming process; 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 focus of the substrate (8); conveying Ti60 powder (5), starting the laser (3), forming a stable molten pool (2) on the substrate (8), controlling the movement of the laser cladding head on the surface of the substrate (8) and performing deposition to obtain a deposited multilayer metal (1), and regulating the metallurgical behavior of the molten pool (2) by the cavitation effect and acoustic streaming effect generated by ultrasound in the molten pool (2); 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 lifting amount of the laser cladding head of 0.1-0.2 mm; thermal conductive glue is filled between the water cooling device and the substrate (8); Step 7: After the deposition is completed, the laser (3) and the ultrasound are turned off in sequence, the conveying of the Ti60 powder (5) is stopped, and the water cooling device and the protective gas are turned off to obtain a Ti60 part with a fine equiaxed crystal structure; 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 a substrate (8); the substrate (8), the ultrasonic horn (9) and the ultrasonic transmitter (10) are rigidly connected.

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 is characterized in that: In step 5, the powder-carrying gas is argon or helium; and the protective gas is argon or helium.

Images