A short pulse laser milling process for laser deposited parts

Abstract

The present invention relates to a short-pulse laser milling process for laser-deposited parts, belonging to the field of micro-nano processing technology. The process includes the following steps: S1: Material preparation: Selecting a 316 stainless steel plate with dimensions of 200mm×200mm×16mm as the deposition substrate, ensuring that the substrate surface is clean and free of oil; S2: Laser deposition process, equipment configuration: Selecting a RofinFL040 kilowatt-class fiber laser; S3: Laser cleaning process; S4: Laser milling process; S5: Data recording and analysis; S6: Process parameter optimization response surface analysis; S7: Result feedback: Adjusting process parameters based on experimental results to optimize milling results; S8: Stability verification and application. The present invention can effectively improve the material removal rate and surface quality during laser milling, and reduce the thickness of the recast layer, thereby overcoming the bottlenecks faced by traditional processing methods in the manufacture of high-complexity, high-precision parts, and has wide applicability.

Description

Technical Field

[0001] The present invention relates to the technical field of laser processing, in particular to a short-pulse laser milling process for laser deposited parts. Background Art

[0002] Inconel 718 nickel-based superalloy is widely used in hot-end components of aircraft engines and industrial gas turbines due to its excellent strength, corrosion resistance, and oxidation resistance above 600°C, showing broad application prospects in fields such as aerospace. Traditional manufacturing methods such as casting and forging are costly and have geometric limitations, making it difficult to meet the manufacturing needs of complex parts. In recent years, the aerospace and related industries have increased demand for lightweight and complex components, and traditional methods have been unable to adapt. Laser additive manufacturing technology has become an effective solution due to its high material utilization and low manufacturing cost, but there is still room for improvement in part dimensional accuracy and surface quality, and post-processing steps are usually required. For complex internal surfaces and narrow internal cavity structures, subsequent mechanical processing is extremely challenging, so additive and subtractive composite manufacturing technology has gradually attracted attention. This technology combines additive manufacturing with traditional machining or high-energy beam subtractive technology.

[0003] Research on laser milling of metal materials is gradually increasing. Laser milling technology has the advantages of non-contact processing, no tool wear, high efficiency and precise control, and is suitable for manufacturing complex parts such as microchannels and cooling channels. However, the current research on laser subtraction of metal additively formed parts is still insufficient, and most of it is focused on mechanical processing. Therefore, conducting research on laser precision subtraction of metal additively formed parts has important scientific significance and engineering value. It can promote the development of additive and subtractive composite manufacturing technology and solve the manufacturing bottleneck problem of high-complexity and high-precision parts. Especially in the field of difficult-to-process materials such as aerospace, the prospects are broad. To this end, a short-pulse laser milling process for laser deposition parts is proposed. Summary of the Invention

[0004] The present invention provides a short-pulse laser milling process for laser-deposited parts, which solves the problems raised by the above-mentioned background technology. It can effectively improve the material removal rate and surface quality during the laser milling process and reduce the thickness of the recast layer, thereby overcoming the bottleneck faced by traditional processing methods in the manufacture of high-complexity and high-precision parts, and has wide applicability.

[0005] The present invention solves the above technical problems with the following solution: a short pulse laser milling process for laser deposited parts, the process method comprising the following steps:

[0006] S1: Select a 316 stainless steel plate with dimensions of 200mm×200mm×16mm as the deposition substrate. Ensure that the substrate surface is clean and free of oil. Use Inconel718 nickel-based alloy powder with an average particle size of 50-150μm. Ensure that the chemical composition of the powder meets the standards. The main components include Fe, Cr, Ni, and Nb.

[0007] S2: Use a Rofin FL040 kilowatt-class fiber laser with an output power of 4000W, a wavelength of 1070nm, and a spot diameter of 1.5mm. Ensure that the laser's cooling system operates normally to avoid overheating.

[0008] S3: Deposition parameter settings: laser power is set to 1000 W, scanning speed is set to 10 mm / s, powder feeding rate is set to 11.3 g / min, and shielding gas flow rate is set to 15 L / min;

[0009] S4: Fix the 316 stainless steel substrate on the workbench of the deposition equipment, turn on the laser, and perform layer-by-layer deposition. The thickness of each layer is controlled at 0.5-1 mm until an Inconel718 laser-deposited part with a final size of 17 mm × 38 mm × 8 mm is formed. The milling parameters are set, the scanning speed is set between 4000-6000 mm / s, the filling spacing is set to 0.01-0.03 mm, and the number of scans is set to 400-800 times;

[0010] S5: Use short pulse laser for cleaning, ensure operation in an inert gas environment, and use nitrogen or helium as the inert gas to prevent oxidation;

[0011] S6: Focus the laser beam on the surface of the deposited part and move it evenly to remove the powder and oxide layer on the surface, achieving a surface roughness Ra of 12.09 μm;

[0012] S7: Laser milling is performed on the surface of the Inconel718 deposited part to mill multiple microchannels with a size of 1 mm × 24 mm. By adjusting the position and movement speed of the laser beam, local melting and removal of the material are achieved;

[0013] S8: The process parameters during milling, including laser power, scanning speed, filling spacing, and number of scans, were recorded. The material removal rate (MRR), surface roughness (Ra), and thickness of the recast layer of the milled parts were measured and evaluated. Laser confocal microscopy and scanning electron microscopy (SEM) were used for detailed observation and characterization.

[0014] On the basis of the above technical solution, the present invention can also be improved as follows.

[0015] Furthermore, in said S5, when setting the cleaning parameters, the power is adjusted to be between 50-100W according to the cleaning needs, a short pulse laser is used, the pulse width is set to 72ns, and the repetition frequency is 100kHz.

[0016] Furthermore, in S4, milling is performed using an RFL-P100M short pulse laser.

[0017] Furthermore, in S4, the parameters of the milling process are set as pulse width: 72 ns, single pulse energy: 1 mJ, maximum power: 100 W, focus spot diameter: 70 μm, and repetition frequency: 100 kHz.

[0018] The beneficial effects of the present invention are as follows: the present invention provides a short-pulse laser milling process for laser deposition parts, which has the following advantages:

[0019] 1. Based on response surface analysis, a mathematical model was established to determine the relationship between laser milling parameters, material removal rate, surface quality, and recast layer. Variance analysis and model validation demonstrated that the model can be used to predict microchannel morphology and optimize process parameters.

[0020] 2. For material removal rate, the number of scans has the most significant impact, followed by the scanning speed. The change of the filling spacing alone has no significant effect on it. However, the interaction between the filling spacing, scanning speed, and the number of scans has an impact on the material removal rate. For surface quality and recast layer, the most significant factor is the scanning speed. The higher the scanning speed, the less recast layer, the fewer defects such as pits and pores at the bottom of the microchannel, and the better the surface quality.

[0021] 3. Through the multi-objective optimization method, the laser milling process parameters were optimized while ensuring the minimum surface roughness and recast layer thickness and the material removal rate. The optimization results were compared with the experimental results, and the optimal process parameters for milling microchannels were obtained: scanning speed 6000mm / s, filling spacing 0.02mm, and scanning times 800 times. Under this parameter, the depth of the microgroove is 921.36, the width is 945.84μm, the bottom surface roughness is 4.97μm, and the left and right wall roughnesses are 2.71μm and 8.49μm respectively; the average thickness of the bottom reconstructed layer is 8.44μm, the thickness of the left and right wall recast layers are 2.97μm and 10.84μm respectively, and the material removal rate is 2.37mm3 / min.

[0022] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and to implement it according to the contents of the description, the following preferred embodiments of the present invention are described in detail with reference to the accompanying drawings. The specific implementation methods of the present invention are given in detail by the following embodiments and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 A schematic diagram of a process flow for a short-pulse laser milling process for laser deposited parts provided by one embodiment of the present invention;

[0025] Figure 2 A schematic diagram of the principle of a short-pulse laser milling process for laser deposited parts provided by one embodiment of the present invention;

[0026] Figure 3 A schematic diagram of measuring surface roughness and recast layer in a short-pulse laser milling process for a laser deposited part according to an embodiment of the present invention;

[0027] Figure 4 A diagram showing the influence of process parameters on MRR in a short-pulse laser milling process for laser deposited parts provided by one embodiment of the present invention;

[0028] Figure 5 A Vickers hardness diagram of a microchannel along a cross section under optimal milling parameters in a short-pulse laser milling process for a laser deposition part provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following is combined with Figure 1-5 The principles and features of the present invention are described, and the examples given are only for the purpose of explaining the present invention and are not intended to limit the scope of the present invention. The following paragraphs describe the present invention in more detail by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are in a very simplified form and are not in exact proportions, and are only used for the purpose of conveniently and clearly assisting in illustrating the embodiments of the present invention.

[0030] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a central component. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a central component. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a central component. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] like Figure 1-5 As shown, the present invention provides a short pulse laser milling process for laser deposited parts, comprising the following steps:

[0033] S1: Material Preparation: Select a 316 stainless steel plate with dimensions of 200mm × 200mm × 16mm as the deposition substrate. Ensure that the substrate surface is clean and free of oil and dirt. Powder Material Preparation: Use Inconel 718 nickel-based alloy powder and confirm that the average particle size of the powder particles is 50-150μm. Ensure that the chemical composition of the powder meets the standards. The main components, including Fe, Cr, Ni, and Nb, meet the following specifications: Cr: 18.72%, Ni: 51.09%, Nb: 5.43%, Mo: 2.88%;

[0034] S2: Laser deposition process, equipment configuration: Use Rofin FL040 kilowatt-class fiber laser with an output power of 4000W, a wavelength of 1070nm, and a spot diameter of 1.5mm. Ensure that the laser's cooling system operates normally to avoid overheating;

[0035] Deposition parameter settings:

[0036] Laser power: 1000W

[0037] Scanning speed: 10mm / s

[0038] Powder feeding rate: 11.3g / min

[0039] Shielding gas flow rate: 15L / min

[0040] Deposition process: The 316 stainless steel substrate is fixed on the workbench of the deposition equipment, the laser is turned on, and the deposition is carried out layer by layer. The thickness of each layer is controlled between 0.5-1mm until the final size of the Inconel718 laser-deposited part with a size of 17mm×38mm×8mm is formed;

[0041] S3: Laser cleaning process

[0042] Equipment configuration: Use short pulse laser for cleaning, ensure operation in an inert gas environment. Nitrogen or helium can be used as a protective gas to prevent oxidation.

[0043] Cleaning parameter settings:

[0044] Laser power: Set between 50-100W according to cleaning needs.

[0045] Pulse width: 72ns

[0046] Repetition frequency: 100kHz

[0047] Cleaning process: Focus the laser beam on the surface of the deposited part and move it evenly to remove the powder and oxide layer on the surface, ensuring that the surface roughness Ra is 12.09μm;

[0048] S4: Laser milling process

[0049] Equipment configuration: RFL-P100M short pulse laser is used for milling. The specific parameters are: pulse width: 72ns, single pulse energy: 1mJ, maximum power: 100W, focus spot diameter: 70μm, repetition rate: 100kHz

[0050] Milling parameter settings:

[0051] Scanning speed: set between 4000-6000mm / s, initially set to 5000mm / s;

[0052] Filling spacing: set to 0.01-0.03mm, initially selected 0.02mm;

[0053] Scan times: set to 400-800 times, initially selected 600 times;

[0054] Milling process:

[0055] Laser milling was performed on the surface of the Inconel 718 deposit, creating multiple microchannels measuring 1mm x 24mm. Localized melting and removal of the material was achieved by adjusting the position and speed of the laser beam.

[0056] S5: Data Recording and Analysis

[0057] Record the process parameters during milling, including laser power, scanning speed, filling spacing and number of scans;

[0058] Measuring and evaluating the properties of milled parts:

[0059] Material removal rate (MRR)

[0060] Surface roughness (Ra)

[0061] Thickness of the recast layer

[0062] Equipment used: Laser confocal microscopy and scanning electron microscopy (SEM) were used for detailed observation and characterization to record the 3D morphology and surface features of the microchannels;

[0063] S6: Response surface analysis for process parameter optimization: Design-Expert V8.0.6 software was used for statistical analysis to optimize process parameters to ensure the best material removal rate, surface quality, and recast layer thickness.

[0064] S7: Result feedback: Based on the experimental results, adjust the process parameters to optimize the milling effect, paying special attention to the interactive effect of scanning speed and filling spacing to maximize processing efficiency and surface quality;

[0065] S8: Stability Verification and Application: Conduct multiple tests to verify the stability of the process to ensure that the expected surface quality and performance requirements can be achieved after each milling process; apply the final prepared Inconel718 laser deposited parts to actual scenarios to evaluate their performance and reliability to verify the practical application value of the process.

[0066] Through the above implementation plan, the short-pulse laser milling process of Inconel718 laser-deposited parts can be effectively realized, the processing accuracy and performance of parts can be improved, and the high requirements of aerospace and other fields can be met.

[0067] Figure 1 (a) Short-pulse laser milling system; (b) Short-pulse laser spot overlap; (c) Schematic diagram of short-pulse laser milling.

[0068] Figure 2 (a) Surface roughness; (b) recast layer;

[0069] Figure 3 (a) The influence of a single factor on MRR; (b) The influence of AB interaction on MRR; (c) The influence of AC interaction on MRR; (d) The influence of BC interaction on MRR;

[0070] It should be noted that, in this document, relational terms such as first and second are used solely to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. Matters not described in detail in this specification are well known to those skilled in the art.

[0071] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A short pulse laser milling process for laser deposited parts, characterized by: The process comprises the following steps: S1: Select a 316 stainless steel plate with dimensions of 200mm×200mm×16mm as the deposition substrate. Ensure that the substrate surface is clean and free of oil. Use Inconel718 nickel-based alloy powder with an average particle size of 50-150μm. Ensure that the chemical composition of the powder meets the standards. The main components include Fe, Cr, Ni, and Nb. S2: Use a Rofin FL040 kilowatt-class fiber laser with an output power of 4000W, a wavelength of 1070nm, and a spot diameter of 1.5mm. Ensure that the laser's cooling system operates normally to avoid overheating. S3: Deposition parameter settings: laser power is set to 1000 W, scanning speed is set to 10 mm / s, powder feeding rate is set to 11.3 g / min, and shielding gas flow rate is set to 15 L / min; S4: Fix the 316 stainless steel substrate on the workbench of the deposition equipment, turn on the laser, and perform layer-by-layer deposition. The thickness of each layer is controlled at 0.5-1 mm until an Inconel718 laser-deposited part with a final size of 17 mm × 38 mm × 8 mm is formed. The milling parameters are set, the scanning speed is set between 4000-6000 mm / s, the filling spacing is set to 0.01-0.03 mm, and the number of scans is set to 400-800 times; S5: Use short pulse laser for cleaning, ensure operation in an inert gas environment, and use nitrogen or helium as the inert gas to prevent oxidation; S6: Focus the laser beam on the surface of the deposited part and move it evenly to remove the powder and oxide layer on the surface, achieving a surface roughness Ra of 12.09 μm; S7: Laser milling is performed on the surface of the Inconel718 deposited part to mill multiple microchannels with a size of 1 mm × 24 mm. By adjusting the position and movement speed of the laser beam, local melting and removal of the material are achieved; S8: The process parameters during milling, including laser power, scanning speed, filling spacing, and number of scans, were recorded. The material removal rate (MRR), surface roughness (Ra), and thickness of the recast layer of the milled parts were measured and evaluated. Laser confocal microscopy and scanning electron microscopy (SEM) were used for detailed observation and characterization.

2. The short pulse laser milling process for laser deposited parts according to claim 1, characterized in that: In said S5, when setting the cleaning parameters, the power is adjusted to be between 50-100 W according to the cleaning needs, a short pulse laser is used, the pulse width is set to 72 ns, and the repetition frequency is set to 100 kHz.

3. The short pulse laser milling process for laser deposition parts according to claim 1, characterized in that: In S4, milling is performed using an RFL-P100M short pulse laser.

4. The short pulse laser milling process for laser deposited parts according to claim 1, characterized in that: In the S4 , the parameters of the milling process are set as pulse width: 72 ns, single pulse energy: 1 mJ, maximum power: 100 W, focus spot diameter: 70 μm, and repetition frequency: 100 kHz.

Images