Preparation method of IN718 alloy through ultrasonic shot peening strengthening and laser directional deposition

Abstract

The invention relates to the technical field of metal material surface engineering and additive manufacturing, in particular to a preparation method of an IN718 alloy through ultrasonic shot peening strengthening and laser directional deposition. According to the composite manufacturing method, through the steps of matrix pretreatment, DED preparation, surface precision treatment and ultrasonic shot blasting treatment, a gradient nanostructure is induced to be generated on the surface layer of the IN 718 alloy, and the microhardness, the wear resistance, the corrosion resistance and the wear-corrosion resistance synergistic performance of the IN 718 alloy are synchronously improved. While near-net forming of a component is achieved through the laser directional energy deposition technology, high dislocation density and high-value residual compressive stress are introduced to the surface layer of a material through subsequent ultrasonic shot peening treatment, grains are remarkably refined, and the effects of regulating and controlling the microstructure and eliminating defects are achieved; and finally, comprehensive improvement of the surface mechanical property and the environmental damage resistance of the component is achieved.

Description

Technical Field

[0001] This invention relates to the field of surface engineering technology for metallic materials, specifically to a method for preparing IN718 alloy by ultrasonic shot peening and laser-directed deposition. Background Technology

[0002] Nickel-based superalloys, especially Inconel 718 (IN718 alloy), are widely used in core components in aerospace (such as aero-engine blades, turbine disks, and casings), energy and power (such as hot-end components of gas turbines), and petrochemical industries due to their excellent high-temperature strength, superior creep resistance, good fatigue resistance, and outstanding corrosion resistance. Laser-directed energy deposition (DED) technology, as an advanced additive manufacturing technology, enables rapid prototyping, near-net-shape forming, and in-service repair of complex IN718 components, offering significant advantages such as high forming freedom, high material utilization, and short manufacturing cycles.

[0003] However, the inherent high energy input, rapid melting and solidification, and repeated thermal cycling characteristics of DED technology easily lead to a series of microstructural defects in the prepared IN718 alloy. These defects mainly include: coarse columnar crystal structures epitaxially growing along the fabrication direction, microscopic segregation of alloying elements (such as Nb and Mo) (forming brittle Laves phase, δ phase, and other harmful precipitates), and high residual tensile stress due to non-uniform thermal stress. These microstructural defects severely restrict the surface integrity of the material, directly manifesting as insufficient surface hardness, poor wear resistance, and decreased corrosion resistance (especially sensitivity to pitting and stress corrosion cracking), making it difficult to meet the stringent requirements of high performance and long service life for critical components under extreme conditions such as high temperature, high stress, and corrosive media. Currently, common methods for improving the surface properties of additively manufactured components include ultrasonic shot peening, laser shock peening, and heat treatment. Ultrasonic shot peening, as a highly efficient surface nanostructuring technology, has been proven to induce gradient nanostructures and residual compressive stress on the surface of traditional metallic materials, thereby improving the fatigue performance and wear resistance of the materials.

[0004] Chinese patent application CN119407196A discloses a method for controlling laser additive manufacturing of nickel-based superalloys using a portable ultrasonic impact device. Through alternating layer-by-layer deposition and ultrasonic impact, grain refinement and hardness enhancement are achieved, with a hardness value reaching approximately 350 HV0.2. Chinese patent application CN118792647A discloses a method for controlling laser cladding of nickel-based superalloy coatings using an integrated lattice ultrasonic vibration device. This method enhances molten pool flow through ultrasonic-assisted technology to promote uniform carbide distribution, and combines this with an in-situ synthesis process to allow C and Nb elements to react and generate a strengthening phase, thereby completely eliminating the harmful Laves phase and improving the coating's wear resistance by 40.5%. Chinese patent application CN120026265A discloses a method for ultrasonic-assisted laser modification to improve the corrosion resistance of magnesium alloys. This method involves ultrasonic-assisted laser treatment of the magnesium alloy surface under a protective atmosphere to form a dense, fine-grained remelted layer with a thickness of approximately 35 μm and a grain size of 1–2 μm. Ultrasonic vibration effectively breaks dendrites, promotes molten pool flow, reduces segregation, significantly refines the microstructure, and improves density, thereby reducing self-corrosion current density and enhancing corrosion resistance. This method is simple, has a short cycle time, and shows good prospects for industrial application.

[0005] However, existing technologies mostly focus on improving traditional bulk materials or single properties (such as hardness or wear resistance). For IN718 alloys specifically prepared using DED technology, how to simultaneously improve wear resistance, corrosion resistance, and, more importantly, the comprehensive performance of wear-corrosion synergy (abrasion resistance) on complex components through systematically optimized ultrasonic shot peening process parameters still lacks in-depth and systematic research, as well as mature and reliable comprehensive process solutions. In particular, existing technologies have not yet provided a clear and effective solution for suppressing the synergistic effect of wear and corrosion failure modes.

[0006] Therefore, there is an urgent need and significant engineering application value to develop a highly efficient and portable surface strengthening method specifically for DED-IN718 alloy components that combines excellent microstructure refinement, hardness enhancement, and corrosion resistance improvement. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for preparing DED-IN718 alloy by ultrasonic shot peening and laser-directed deposition. The process is simple and the strengthening effect is significant. The method prepares a modified layer with a gradient structure on the surface of DED-IN718 alloy, which simultaneously improves its microhardness, wear resistance, corrosion resistance and resistance to wear-corrosion synergistic damage.

[0008] The technical solution adopted is as follows: A method for preparing IN718 alloy by ultrasonic shot peening and laser-directed deposition includes the following steps: a. Substrate pretreatment: 45 steel was selected as the deposition substrate, and the surface was degreased and derusted; b. DED preparation: IN718 alloy samples were prepared on the pretreated substrate using laser-directed energy deposition technology; c. Surface finishing: Mechanical grinding and polishing are performed on the surface of the deposited sample to achieve a certain surface finish and ensure the uniformity of the ultrasonic shot peening effect.

[0009] d. Ultrasonic shot peening: The surface of the sample from step c is strengthened using a portable ultrasonic shot peening device; e. Post-treatment: Ultrasonic cleaning of the sample surface is used to remove surface contaminants and ensure the accuracy and reliability of subsequent analysis, testing or experimental results.

[0010] Preferably, in step a, the substrate is derusted using an angle grinder and then wiped with anhydrous ethanol to remove oil stains, controlling the surface roughness Ra to be between 3.2 and 6.3 μm.

[0011] Preferably, in step b, the alloy powder used for laser directional energy deposition is IN718 nickel-based high-temperature alloy powder with a particle size of 50-150 μm; Place IN718 nickel-based high-temperature alloy powder in the powder feeder and run it for 10-20 seconds to ensure uniform powder feeding and guarantee deposition quality.

[0012] Preferred, set up The laser power is set to 1000W-1800W, the scanning speed is 4-10mm / s, the powder feeding rate is 0.8-1.5r / min, and the layer height is 0.5-0.8mm.

[0013] Preferably, the overlap ratio is set to 1-1.5mm, and the protective gas is argon.

[0014] Preferably, the argon gas has a purity of 99% or higher and a flow rate of 15-25 L / min.

[0015] Preferably, there are at least two deposition layers; after the first layer is deposited, the second, third, and fourth layers are deposited, and so on.

[0016] Preferably, in step c, after fine treatment, the surface roughness Ra is 1.6-3.2 μm.

[0017] Preferably, in step d, the instrument power is set to 55%-70% of the rated power, the working frequency is 18-22kHz, and the ultrasonic shot peening time is 5-40min; the shot used is a quenched steel ball with a diameter of 1-8mm.

[0018] Preferably, after ultrasonic shot peening, the surface microhardness of the IN718 alloy component reaches 400-500HV0.2.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: Significant tissue refinement effect: Ultrasonic shot peening effectively breaks the coarse columnar crystals of DED-IN718, refining the average grain size from 50-100μm to 2-5μm, forming a continuous gradient nanostructure on the surface and eliminating anisotropy.

[0020] The mechanical properties are comprehensively improved: the surface microhardness is increased from 250-300HV0.2 to 400-500HV0.2, an increase of 60%-100%, which is more significant than the hardness improvement in Chinese patent application CN119407196A. The hardness is distributed in a smooth gradient, avoiding interface failure.

[0021] Significantly improved wear resistance: The coefficient of friction under dry sliding wear conditions decreased from 0.6 to 0.5. The high hardness directly endowed it with excellent resistance to abrasive cutting, and the wear rate was reduced by 32.7%.

[0022] Significantly improved corrosion resistance: In a 3.5 wt.% NaCl solution, the corrosion potential shifted positively from -0.21 V to -0.18 V, and the corrosion current density increased from 3.36 × 10⁻⁻⁻⁶. 7 A / cm² decreased to 8.56×10⁻ 8 A / cm², charge transfer resistance is increased by 50%-100%, and passivation film stability is enhanced.

[0023] Excellent anti-wear and corrosion performance: Under the synergistic effect of wear and corrosion, the total material loss is reduced by 50%-70%, effectively suppressing the mutual acceleration effect of wear and corrosion, and maintaining stable low friction characteristics in corrosive media.

[0024] The process has significant advantages: high processing efficiency, processing time ≤30min, portable equipment, suitable for on-site operations and complex geometric components, green and environmentally friendly, pollution-free, low cost, simple operation, and easy to industrialize.

[0025] This invention utilizes an optimized ultrasonic shot peening process to construct a gradient nanostructure on the surface of DED-IN718 alloy, achieving simultaneous improvement in wear resistance, corrosion resistance, and anti-erosion properties. This provides an effective technical solution for surface strengthening of key components in aerospace, energy, and chemical industries. Attached Figure Description

[0026] Figure 1The image shows a comparison of the microstructure of the DED-IN718 nickel-based superalloy prepared in Example 1(b) and Comparative Example 1(a) of this invention using scanning electron microscopy. Figure 2 The electron backscatter diffraction (EBSD) patterns of the DED-IN718 nickel-based superalloys prepared in Example 1(b) and Comparative Example 1(a) of the present invention are shown.

[0027] Figure 3 This is a comparison diagram of the microhardness gradient distribution from the surface to the core of the DED-IN718 nickel-based superalloy prepared in Example 1 and Comparative Example 1 of the present invention.

[0028] Figure 4 The friction coefficient curve (a) and wear rate (b) of the DED-IN718 nickel-based superalloy prepared in Example 1 and Comparative Example 1 under dry sliding wear conditions are compared. Figure 5 The potentiodynamic polarization curves of the DED-IN718 nickel-based superalloy prepared in Example 1 and Comparative Example 1 of this invention in 3.5 wt.% NaCl solution are shown. Figure 6 The graph shows a comparison of the OCP (a), friction coefficient curve (b), and wear rate (c) of the nickel-based superalloys prepared in Example 1 and Comparative Example 1 under the synergistic effect of wear and corrosion. Detailed Implementation

[0029] The accompanying drawings are for illustrative purposes only; the technical solutions of the present invention will be described in detail below with reference to specific embodiments and the accompanying drawings.

[0030] It should be understood that prior art and common knowledge may be omitted, and the technical solution of the present invention is not limited to the following embodiments.

[0031] Example 1 A method for preparing IN718 alloy by ultrasonic shot peening and laser-directed deposition includes the following steps: (1) Substrate pretreatment: 45 steel was selected as the deposition substrate and surface degreasing and derusting treatment was performed. The pretreatment method was to use an angle grinder to remove rust from the substrate and then wipe the substrate with anhydrous ethanol to remove surface oil and control the surface roughness Ra to 4.5μm.

[0032] (2) IN718 alloy samples were prepared on the pretreated substrate using laser directional energy deposition technology. The substrate after removing oil was placed on the worktable, and IN718 nickel-based high-temperature alloy powder with a particle size of about 80 μm was placed in the powder feeder and run for 15 s to ensure uniform powder feeding and guarantee deposition quality.

[0033] In an argon atmosphere, IN718 nickel-based superalloy powder from a powder feeder is laser-directed energy deposition (LDED) onto a substrate. The laser power for LDED is 1500W, the scanning speed is 8mm / s, the powder feeding rate is 1r / min, and the number of deposition layers is 3.

[0034] (3) Surface finishing: Mechanical grinding and polishing are performed on the surface of the deposited sample to achieve a certain surface finish and ensure the uniformity of the ultrasonic shot peening effect.

[0035] (4) Ultrasonic shot peening. The deposited layer on the surface-finished nickel-based superalloy substrate was subjected to ultrasonic impact using a portable ultrasonic shot peening device. The working frequency was 20kHz, the ultrasonic shot peening power was 60% of the rated power, the ultrasonic shot peening time was 20min, and the shot used was a quenched steel ball with a diameter of 4mm.

[0036] (5) Post-treatment: Ultrasonic cleaning is used. ， To eliminate surface contaminants and ensure the accuracy and reliability of subsequent analysis, testing, or experimental results, it is designated as USP-1.

[0037] Comparative Example 1 A method for preparing enhanced laser-directed deposition IN718 alloy includes the following steps: (1) Substrate pretreatment: 45 steel was selected as the deposition substrate and surface degreasing and derusting treatment was performed. The pretreatment method was to use an angle grinder to remove rust from the substrate and then wipe the substrate with anhydrous ethanol to remove surface oil and control the surface roughness Ra to 4.5μm.

[0038] (2) IN718 alloy samples were prepared on the pretreated substrate using laser directional energy deposition technology. The substrate after removing oil was placed on the worktable, and IN718 nickel-based high-temperature alloy powder with a particle size of about 80 μm was placed in the powder feeder and run for 15 s to ensure uniform powder feeding.

[0039] In an argon atmosphere, IN718 nickel-based superalloy powder from a powder feeder is laser-directed energy deposition (LDED) onto a substrate. The laser power for LDED is 1500W, the scanning speed is 8mm / s, and the powder feeding rate is 1r / min. The number of deposition layers is 3.

[0040] (3) Surface treatment. The deposited nickel-based alloy microstructure is mechanically ground and polished to remove the uneven layer on the surface of the deposited nickel-based alloy, and a smooth and uniform surface is obtained with Ra of about 2.5 μm. The laser-directed deposited IN718 alloy component is obtained and denoted as ASP.

[0041] The gradient nanostructure alloy component USP-1 obtained in Example 1 was compared with the alloy component ASP obtained in the comparative example. Figure 1 The image shown is a comparison of microscopic tissue morphology obtained using scanning electron microscopy (SEM). Figure 1 In image (b), a gradient structure is formed after ultrasonic shot peening, while in image (a), although the structure is uniform, no gradient is visible. Through... Figure 2 As can be seen from the electron backscatter diffraction (EBSD) pattern, Figure 2 In (b), after ultrasonic shot peening, the grains of the material are significantly refined and the number of grain boundaries is significantly increased, which indirectly indicates that beneficial compressive residual stress may be introduced on the surface, which is conducive to inhibiting crack initiation and propagation, thereby enhancing fatigue life.

[0042] like Figure 3 As shown, USP treatment creates a significant hardness gradient in the near-surface region of the material, with a surface hardness value much higher than ASP, gradually decreasing with increasing depth and approaching the matrix level. USP, through high-energy ultrasonic vibration, induces more intense and uniform plastic deformation of the material surface by the shot peening particles. This deformation directly leads to two key microstructural changes: a sharp increase in dislocation density and significant grain refinement (as shown in the EBSD image). Dislocation multiplication and interaction constitute a strengthened matrix; simultaneously, the finer grains further enhance strength and hardness according to the Hall-Page effect.

[0043] like Figure 4 As shown, the friction coefficient of the ASP sample fluctuated significantly with large amplitude throughout the test period. Its average value was high (approximately 0.5), and it did not exhibit a clear stable phase, remaining in a continuously unstable state. The friction coefficient of the USP-1 sample experienced a brief increase in the initial stage of the test (approximately 0-50 seconds), followed by a rapid decrease and entry into a stable phase. Its steady-state friction coefficient was low (approximately 0.35), and the curve was smooth throughout the test with minimal fluctuation. Furthermore, compared to ASP, the wear rate of USP-1 was reduced by approximately 32.7%. Surface nano-sizing / refining and increased hardness are the main reasons for this.

[0044] like Figure 5 As shown, the USP-1 sample has a higher corrosion potential and a lower corrosion current density, which indicates that the surface of the material treated with USP is more thermodynamically stable, less prone to corrosion, and has a slower corrosion reaction rate, meaning that it has better corrosion resistance in real-world environments.

[0045] like Figure 6As shown, the USP-1 sample maintained a consistently high and stable open-circuit potential throughout the entire 6000-second test, indicating an extremely stable surface condition. This suggests that the protective passivation film or reinforcement layer remained intact and effective in isolating the corrosive medium during wear. The ASP sample, on the other hand, exhibited a significantly lower open-circuit potential (approximately -0.4V to -0.5V) and drastically fluctuated. Frequent sharp negative shifts in potential (indicating surface activation / damage) followed by partial recovery (possibly due to temporary coverage by corrosion products) revealed the continuous damage and repeated exposure of its surface to fresh, active metal under wear. Under the synergistic effect of abrasion (wear + corrosion), the USP treatment's enhancement of the 718 alloy's surface microstructure altered the dominant mechanism of friction and wear, resulting in a higher average coefficient of friction than the softer ASP sample. Due to its extremely fine grains and high dislocation density, it facilitated the formation of an extremely thin (nanoscale), extremely hard, and highly adhesive Cr2O3-based passivation film in the corrosive medium. Under the mechanical action of wear, this hard and brittle nano-oxide film is easily broken, peeling off to form nanoscale hard oxide abrasive grains (such as Cr2O3, NiO, etc.). These hard abrasive grains, originating from their own passivation film, have a hardness far exceeding that of the alloy matrix. Their retention at the friction interface generates significant plowing and micro-cutting effects. This three-body abrasive wear mechanism requires a large amount of energy, directly leading to a substantial increase in the coefficient of friction.

[0046] However, the wear rate of USP-1 is significantly lower than that of ASP. In practical engineering, especially in abrasive environments, the primary criterion for judging the success or failure of surface treatment is the rate and total amount of material loss (i.e., wear rate or weight loss). USP-1 achieves extremely low material loss at the cost of higher frictional energy consumption, which is a fundamental victory for extending the life of critical components.

[0047] Example 2 A method for preparing IN718 alloy by ultrasonic shot peening and laser-directed deposition includes the following steps: (1) Substrate pretreatment: 45 steel was selected as the deposition substrate and surface degreasing and derusting treatment was performed. The pretreatment method was to use an angle grinder to remove rust from the substrate and then wipe the substrate with anhydrous ethanol to remove surface oil and control the surface roughness Ra to 5.5 μm.

[0048] (2) IN718 alloy samples were prepared on the pretreated substrate using laser-directed energy deposition technology. The substrate after removing oil was placed on the worktable, and IN718 nickel-based high-temperature alloy powder with a particle size of 80μm was placed in the powder feeder and run for 15s to ensure uniform powder feeding and guarantee deposition quality.

[0049] In an argon atmosphere, IN718 nickel-based superalloy powder from a powder feeder is laser-directed energy deposition (LDED) onto a substrate. The laser power for LDED is 1000W, the scanning speed is 8mm / s, and the powder feeding rate is 1r / min. The number of deposition layers is 3.

[0050] (3) Surface finishing: Mechanical grinding and polishing are performed on the surface of the deposited sample to achieve a certain surface finish and ensure the uniformity of the ultrasonic shot peening effect.

[0051] (4) Ultrasonic shot peening: The deposited layer on the surface-finished nickel-based alloy substrate can be ultrasonically impacted using a portable ultrasonic shot peening device. Among them, work The operating frequency was 20kHz, the ultrasonic shot peening power was 60% of the rated power, the ultrasonic shot peening time was 20min, and the shot used was a quenched steel ball with a diameter of 4mm.

[0052] (5) Post-processing: Ultrasonic cleaning is used to remove surface contaminants and ensure the accuracy and reliability of subsequent analysis, testing or experimental results. The final alloy component is designated as USP-2.

[0053] Example 3 A method for preparing IN718 alloy by ultrasonic shot peening and laser-directed deposition, wherein the laser power of laser-directed energy deposition is 1800W, and the final alloy component is designated as USP-3.

[0054] Other areas not mentioned are the same as in Example 1.

[0055] Example 4 A method for preparing IN718 alloy by ultrasonic shot peening and laser-directed deposition, wherein the scanning speed of laser-directed energy deposition is 4 mm / s, and the final alloy component is designated as USP-4.

[0056] Other areas not mentioned are the same as in Example 1.

[0057] Example 5 A method for preparing IN718 alloy by ultrasonic shot peening and laser-directed deposition, wherein the scanning speed of laser-directed energy deposition is 6 mm / s, and the final alloy component is designated as USP-5.

[0058] Other areas not mentioned are the same as in Example 1.

[0059] Example 6 A method for preparing IN718 alloy by ultrasonic shot peening and laser-directed deposition, wherein the number of deposition layers in the laser-directed energy deposition is 2, and the final alloy component is designated as USP-6.

[0060] Other areas not mentioned are the same as in Example 1.

[0061] Example 7 A method for preparing an ultrasonic shot peening strengthened laser-directed deposition IN718 alloy, wherein the number of deposition layers in the laser-directed energy deposition is 4, and the final alloy component is designated as USP-7.

[0062] Other areas not mentioned are the same as in Example 1.

[0063] Example 8 A method for preparing IN718 alloy by ultrasonic shot peening and laser-directed deposition. overtake The acoustic shot peening power was 40% of the rated power, and the resulting alloy component was designated as USP-8.

[0064] Other areas not mentioned are the same as in Example 1.

[0065] Example 9 A method for preparing IN718 alloy by ultrasonic shot peening and laser directional deposition, wherein the shot used is a quenched steel ball with a diameter of 2 mm, and the final alloy component is designated as USP-9.

[0066] Other areas not mentioned are the same as in Example 1.

[0067] Example 10 A method for preparing IN718 alloy by ultrasonic shot peening enhanced laser directional deposition, wherein the ultrasonic shot peening time is 10 min, and the final alloy component is designated as USP-10.

[0068] Other areas not mentioned are the same as in Example 1.

[0069] Example 11 A method for preparing IN718 alloy by ultrasonic shot peening enhanced laser directional deposition, wherein the ultrasonic shot peening time is 30 min, and the final alloy component is designated as USP-11.

[0070] Other areas not mentioned are the same as in Example 1.

[0071] The IN718 alloy components prepared in Examples 1-11 were subjected to surface microhardness testing; the coefficient of friction under dry sliding wear conditions was tested; the corrosion potential and corrosion current density were tested in a 3.5 wt.% NaCl solution; the total material loss under the synergistic effect of wear and corrosion was tested, and the improvement rate of wear-corrosion resistance was calculated. The results are shown in Table 1.

[0072] Table 1. Performance comparison of IN718 alloy components prepared in Examples 1-11 As shown in Table 1, this study prepared USP series alloy components by systematically designing laser cladding and ultrasonic shot peening process parameters, and comprehensively evaluated their surface microhardness, electrochemical corrosion resistance, and wear-corrosion synergistic performance. The analysis results confirm that the USP-1 parameter combination of 1500W laser power, 8mm / s scanning speed, 60% ultrasonic power, 4mm diameter quenched steel ball, and 20min working time achieves optimal synergy and balance of various key performance characteristics, demonstrating comprehensive superiority.

[0073] Specifically, the USP-1 component exhibits the most outstanding corrosion protection, with the most positive corrosion potential (-0.186V) and the lowest corrosion current density (3.359×10⁻⁻⁶V). 7 The A / cm² (aluminum per square meter) indicates that its surface forms the most stable and densest microstructure, effectively inhibiting the electrochemical corrosion process. Simultaneously, its wear-corrosion resistance improvement rate reaches 63%, meaning that in harsh environments where wear and corrosion intensify, USP-1 exhibits the strongest overall ability to resist material loss, significantly superior to other parameter combinations. Furthermore, its surface microhardness reaches 489.095 HV, which, while not the highest, is ideally matched with optimal corrosion resistance and resistance to synergistic wear, avoiding the brittleness and reduced corrosion resistance that might result from simply pursuing high hardness.

[0074] Comparative analysis of other parameter groups reinforces this conclusion from the opposite perspective. Any deviation from a single parameter, such as a decrease or increase in laser power, a change in scanning speed, or insufficient ultrasonic power, will disrupt the delicate performance balance described above. For example, increasing the laser power (USP-3) slightly increases the hardness to 495.5 HV, but leads to overheating of the microstructure, resulting in a sharp deterioration in corrosion resistance and abrasion-corrosion resistance; decreasing the ultrasonic power (USP-6) weakens the grain refinement and densification effects, causing a comprehensive decline in all performance indicators. These results clearly demonstrate that the parameter window of USP-1 precisely controls the heat input, cooling rate, and microstructure evolution during the cladding process, making it the optimal process for obtaining strong, corrosion-resistant, and highly abrasion-corrosion-resistant materials. This has clear theoretical value and practical significance for guiding the actual preparation of high-performance surface protective coatings.

[0075] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for preparing IN718 alloy by ultrasonic shot peening and laser-directed deposition, characterized in that, Includes the following steps: a. Substrate pretreatment: 45 steel was selected as the deposition substrate, and the surface was degreased and derusted; b. DED preparation: IN718 alloy samples were prepared on the pretreated substrate using laser-directed energy deposition technology; c. Surface finishing: Mechanical grinding and polishing are performed on the surface of the deposited sample to achieve a certain surface finish; d. Ultrasonic shot peening: The surface of the sample from step c is strengthened using a portable ultrasonic shot peening device; e. Post-treatment: The sample surface is cleaned with ultrasonic waves to obtain a reinforced IN718 alloy component with a gradient nanostructure on the surface.

2. The method for preparing an ultrasonic shot-peening strengthened laser-directed deposition IN718 alloy according to claim 1, characterized in that, In step a, the substrate is derusted using an angle grinder and then wiped with anhydrous ethanol to remove oil stains, controlling the surface roughness Ra to be between 3.2 and 6.3 μm.

3. The method for preparing an ultrasonically shot-peened laser-directed deposition IN718 alloy according to claim 1, characterized in that, In step b, the alloy powder used for laser directional energy deposition is IN718 nickel-based high-temperature alloy powder with a particle size of 50-150 μm. Place IN718 nickel-based high-temperature alloy powder in the powder feeder and run it for 10-20 seconds to ensure uniform powder feeding.

4. The method for preparing an ultrasonically shot-peened laser-directed deposition IN718 alloy according to claim 3, characterized in that, Set the laser power to 1000W-1800W, scanning speed to 4-10mm / s, powder feeding rate to 0.8-1.5r / min, and layer height to 0.5-0.8mm.

5. The method for preparing an ultrasonically shot-peened laser-directed deposition IN718 alloy according to claim 4, characterized in that, The overlap ratio is set to 1-1.5mm, the layer thickness to 2-4mm, and the protective gas is argon.

6. The method for preparing an ultrasonically shot-peened laser-directed deposition IN718 alloy according to claim 5, characterized in that, Argon gas purity is above 99%, and flow rate is 15-25 L / min.

7. The method for preparing an ultrasonic shot-peening strengthened laser-directed deposition IN718 alloy according to claim 6, characterized in that, At least two layers should be deposited.

8. The method for preparing an ultrasonic shot-peening strengthened laser-directed deposition IN718 alloy according to claim 1, characterized in that, In step c, after fine treatment, the surface roughness Ra is 1.6-3.2 μm.

9. The method for preparing an ultrasonically shot-peened laser-directed deposition IN718 alloy according to claim 1, characterized in that, During step d, the instrument power is set to 55%-70% of the rated power, the working frequency is 18-22kHz, and the ultrasonic shot peening time is 5-40min; the shot used is a quenched steel ball with a diameter of 1-5mm.

10. The method for preparing an ultrasonically shot-peened laser-directed deposition IN718 alloy according to claim 1, characterized in that, After ultrasonic shot peening, the surface microhardness of the IN718 alloy component reaches 400-500HV0.2.

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