Ultrafast laser composite additive manufacturing method for high-temperature alloy difficult to weld

Abstract

The invention relates to an ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, which comprises the following steps: determining the particle size and physical parameters of the difficult-to-weld high-temperature alloy, determining the melting technical parameters and laser shock peening parameters of a laser powder bed based on the particle size and physical parameters of the difficult-to-weld high-temperature alloy, and flatly laying the difficult-to-weld high-temperature alloy on a workbench for printing. Additive laser and ultrafast laser are subjected to layer-by-layer strengthening or follow-up strengthening printing to obtain a difficult-to-weld high-temperature alloy forging test piece, the difficult-to-weld high-temperature alloy forging printing test piece is subjected to machining and heat treatment to obtain a difficult-to-weld high-temperature alloy additive test piece, the difficult-to-weld high-temperature alloy forging printing test piece is cut off from a base plate through machining, and the surface of the difficult-to-weld high-temperature alloy forging printing test piece is kept flat; and then heat treatment is performed to eliminate internal defects to obtain the refractory high-temperature alloy additive test piece.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing and laser surface modification, and in particular to an ultrafast laser composite additive manufacturing method for difficult-to-weld high-temperature alloys. Background Art

[0002] Difficult-to-weld superalloys, such as nickel-based superalloys, are suitable for applications such as turbine blades, gas turbines, turbocharger rotors, and nuclear reactors. Operating temperatures can exceed 700°C, and they exhibit resistance to creep, fatigue, oxidation, and corrosion. Difficult-to-weld superalloys are considered unweldable when the aluminum and titanium content exceeds 5wt%. Because Al and Ti are the primary strengthening phases in superalloys, rapid thermal cycling and complex thermal stress distribution during additive manufacturing can increase the material's cracking susceptibility. Furthermore, the high melting points and poor thermal conductivity of these alloying elements can lead to segregation at high-angle grain boundaries, causing a liquefaction effect. This makes it difficult to stably control the temperature and flow fields of the melt pool during printing, thus affecting the microstructure and performance of the final product. Furthermore, regarding process control, the process parameters for difficult-to-weld superalloys are interconnected, such as scanning speed, spot diameter, layer thickness, and scanning pitch. Even small changes in these parameters can significantly impact the quality and performance of the superalloy specimen. Due to the complexity and variability of the additive manufacturing process, the quality of test pieces often varies significantly between batches. This quality inconsistency not only increases the difficulty of subsequent quality inspection and repair, but also limits the application of printing technology in large-scale production. Finally, the high price of high-performance, difficult-to-weld high-temperature alloys leads to high production costs, making large-scale promotion and application difficult.

[0003] Therefore, in summary, the additive manufacturing technology of difficult-to-weld high-temperature alloys faces urgent problems in terms of material properties, process optimization, quality consistency and cost.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0005] This invention provides an ultrafast laser composite additive manufacturing method and system for difficult-to-weld high-temperature alloys. By combining additive manufacturing with ultrafast lasers, high-pressure shock waves are introduced to modify the surface of the resulting molten layer, enabling precise control of the stress field within the molten layer. This method addresses various defects caused by uneven internal thermal stress in difficult-to-weld high-temperature alloys during additive manufacturing, such as microcracks, holes, and deformation. Furthermore, the invention also improves the mechanical properties of high-temperature alloy specimens.

[0006] An ultrafast laser composite additive manufacturing method for difficult-to-weld high-temperature alloys includes: Step S1: determining the particle size and physical parameters of the difficult-to-weld high-temperature alloy, and determining the size of the difficult-to-weld high-temperature alloy additive test piece to be manufactured based on the particle size and physical parameters of the difficult-to-weld high-temperature alloy, wherein the physical parameters include element content and melting point; Step S2: Determine laser powder bed fusion technical parameters and laser shock peening parameters based on the particle size and physical parameters of the difficult-to-weld high-temperature alloy. The laser powder bed fusion technical parameters include the laser scanning path, scanning speed, layer thickness, scanning spacing of the additive laser, and the rotation angle between the starting point of the next layer and the angle of the previous layer after each layer is printed. The laser shock peening parameters include the pulse energy, pulse width, wavelength, frequency, spot diameter, overlap rate, scanning path, scanning spacing of the ultrafast laser, and the rotation angle between the starting point of the next layer and the angle of the previous layer after each layer is printed. Step S3: The difficult-to-weld high-temperature alloy is laid flat on a workbench and prepared for printing based on the size of the difficult-to-weld high-temperature alloy additive manufacturing specimen to be manufactured. The substrate is preheated to a predetermined temperature, the laser printing position is adjusted, the wind speed is set, the hatch is closed, and the argon shielding gas is turned on to ensure that the oxygen content is less than 0.3wt%. Step S4: The additive laser and the ultrafast laser perform layer-by-layer strengthening or follow-up strengthening printing to obtain a forged specimen of a difficult-to-weld high-temperature alloy. In the layer-by-layer strengthening, the additive laser prints a layer and then the ultrafast laser performs strengthening. The time interval between the additive laser and the ultrafast laser is based on the time it takes for the additive laser to complete a layer. In the follow-up strengthening, the paths of the additive laser and the ultrafast laser are kept consistent. The additive laser prints and the ultrafast laser follows to perform strengthening. The interval time is set according to the distance between the additive laser and the ultrafast laser, and the interval time is ≥ 0s. Step S5: The difficult-to-weld high-temperature alloy forged printed specimen is subjected to mechanical processing and heat treatment to obtain a difficult-to-weld high-temperature alloy additive specimen, wherein the difficult-to-weld high-temperature alloy forged printed specimen is cut from the substrate by mechanical processing while keeping the surface flat, and then the difficult-to-weld high-temperature alloy additive specimen is obtained by heat treatment to eliminate internal defects.

[0007] In the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, the total content of aluminum and titanium in the difficult-to-weld high-temperature alloy exceeds 5wt%, and the ultrafast laser includes a picosecond laser and a femtosecond laser.

[0008] In the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, the difficult-to-weld high-temperature alloy is in powder form with a particle size of 10μm to 100μm; the difficult-to-weld high-temperature alloy includes alloying elements such as Ni, Cr, Ti, Al, W, and Mo, and the operating temperature of the difficult-to-weld high-temperature alloy is 600°C to 1100°C.

[0009] In the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, the size of the difficult-to-weld high-temperature alloy additive test piece is related to its hardness, micromorphology and metallography.

[0010] In the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, the laser powder bed melting technical parameters include a laser scanning path including an offset scanning path, a strip path, or a grid path, a scanning speed of 200 mm / s to 2000 mm / s, a scanning pitch of 50 mm to 200 mm, a layer thickness of micrometers to millimeters, and a rotation speed of 67°C or 90°C.

[0011] In the ultrafast laser composite additive manufacturing method for difficult-to-weld high-temperature alloys, the scanning pitch is related to the overlap rate of the light spots, the offset scanning path includes a Z-shaped path, and the scanning path, scanning speed, and rotation speed of the ultrafast laser are the same as the scanning path, scanning speed, and rotation speed of the additive laser.

[0012] In the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, the laser shock peening parameters include a pulse width of picosecond and femtosecond scales; a wavelength of 1064 nm, a frequency of 10 kHz to 2 MHz, a spot diameter of 40 μm to 350 μm; and an overlap rate of 50% to 75%.

[0013] In the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, the predetermined temperature of the substrate does not exceed 200° C.; and the wind field speed is 2.6 mm / s.

[0014] In the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, mechanical processing includes a first step of wire cutting or electric spark cutting, a second step of cutting or lathe processing to maintain surface smoothness and flatness, and heat treatment includes annealing, normalizing, quenching, solution treatment or aging treatment.

[0015] A manufacturing system for implementing the method includes: A workbench comprising, substrate, which supports the difficult-to-solder high-temperature alloy, a working chamber, which seals the substrate and provides an argon protective atmosphere, An additive laser, which prints difficult-to-weld high-temperature alloys in the working chamber based on laser powder bed fusion technology parameters, Ultrafast laser, which prints difficult-to-weld high-temperature alloys based on laser shock peening parameters in the working chamber, and additive laser and ultrafast laser perform layer-by-layer strengthening or follow-up strengthening printing to obtain difficult-to-weld high-temperature alloy forging specimens, Machining unit, which cuts the hard-to-weld high-temperature alloy forging print specimen from the substrate and keeps the surface flat, The heat treatment unit heat treats the difficult-to-weld high-temperature alloy forged printed specimen to eliminate internal defects and obtain a difficult-to-weld high-temperature alloy additive specimen.

[0016] Compared with the existing technology, the present invention has the following advantages: the present invention combines additive technology with ultrafast laser surface strengthening technology. On the one hand, it can accurately adjust the stress field of the molten layer, solve the problem of residual stress inside the components during the additive manufacturing process, and reduce defects such as deformation, cracking and holes in the components; on the other hand, the present invention can refine the grains, precipitate the hardened phase, and convert internal residual tensile stress into compressive stress at the micro level, thereby significantly improving the mechanical properties of the components; on the third hand, the present invention integrates the design of components, greatly reducing the complexity of the component processing process and other problems, and can effectively improve manufacturing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are intended only to illustrate preferred embodiments and are not to be construed as limiting the present invention. It should be understood that the drawings described below are merely examples of the present invention, and that those skilled in the art will be able to derive other drawings from these drawings without inventive effort. Throughout the drawings, identical reference numerals are used to denote identical components.

[0018] In the attached figure: Figure 1 1 is a schematic diagram of the system structure of a preferred embodiment of the present invention; Figure 2 FIG. 1 is a schematic diagram of a scanning path of a preferred embodiment of the present invention, wherein: Figure 2 (a) is the bias scan; Figure 2 (b) in the middle is a strip scan; Figure 2 Middle (c) is a chessboard scan; Figure 3 It is a schematic diagram of a method flow chart of a preferred embodiment of the present invention; Figure 4 Schematic diagrams of the surface morphology of three embodiments of the present invention.

[0019] The present invention will be further explained below with reference to the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0020] Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0021] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of the present invention shall be as defined in the attached claims.

[0022] To facilitate understanding of the embodiments of the present invention, further explanation will be given below using specific embodiments as examples in conjunction with the accompanying drawings, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0023] like Figures 1 to 4 As shown in FIG, the ultrafast laser composite additive manufacturing method for difficult-to-weld high-temperature alloys includes the following steps: Step S1: Determine the particle size and physical parameters of the difficult-to-weld high-temperature alloy, and determine the size of the difficult-to-weld high-temperature alloy additive test piece to be manufactured based on the particle size and physical parameters of the difficult-to-weld high-temperature alloy. The physical parameters include element content and melting point. The powder particle size is 18um~53um, and the test piece size is determined based on the equipment format, which can be 150mm. 150mm, or 300mm 300mm; the physical parameters include element content and melting point; Step S2: Determine laser powder bed fusion technical parameters and laser shock peening parameters based on the particle size and physical parameters of the difficult-to-weld high-temperature alloy. The laser powder bed fusion technical parameters include the laser scanning path, scanning speed, layer thickness, scanning spacing of the additive laser, and the rotation angle between the starting point of the next layer and the angle of the previous layer after each layer is printed. The laser shock peening parameters include the pulse energy, pulse width, wavelength, frequency, spot diameter, overlap rate, scanning path, scanning spacing of the ultrafast laser, and the rotation angle between the starting point of the next layer and the angle of the previous layer after each layer is printed. Step S3: The difficult-to-weld high-temperature alloy is laid flat on a workbench and prepared for printing based on the size of the difficult-to-weld high-temperature alloy additive manufacturing specimen to be manufactured. The substrate is preheated to a predetermined temperature, the laser printing position is adjusted, the wind speed is set, the hatch is closed, and the argon shielding gas is turned on to ensure that the oxygen content is less than 0.3wt%. Step S4: The additive laser and the ultrafast laser perform layer-by-layer strengthening or follow-up strengthening printing to obtain a forged specimen of a difficult-to-weld high-temperature alloy. In the layer-by-layer strengthening, the additive laser prints a layer and then the ultrafast laser performs strengthening. The time interval between the additive laser and the ultrafast laser is based on the time it takes for the additive laser to complete a layer. In the follow-up strengthening, the paths of the additive laser and the ultrafast laser are kept consistent. The additive laser prints and the ultrafast laser follows to perform strengthening. The interval time is set according to the distance between the additive laser and the ultrafast laser, and the interval time is ≥ 0s. Step S5: The difficult-to-weld high-temperature alloy forged printed specimen is subjected to mechanical processing and heat treatment to obtain a difficult-to-weld high-temperature alloy additive specimen, wherein the difficult-to-weld high-temperature alloy forged printed specimen is cut from the substrate by mechanical processing while keeping the surface flat, and then the difficult-to-weld high-temperature alloy additive specimen is obtained by heat treatment to eliminate internal defects.

[0024] In a preferred embodiment of the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, the total content of aluminum and titanium in the difficult-to-weld high-temperature alloy exceeds 5wt%, and the ultrafast laser includes a picosecond laser and a femtosecond laser.

[0025] In a preferred embodiment of the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, the difficult-to-weld high-temperature alloy is in powder form with a particle size of 10μm to 100μm; the difficult-to-weld high-temperature alloy includes alloying elements of Ni, Cr, Ti, Al, W and Mo, and the operating temperature of the difficult-to-weld high-temperature alloy is 600℃ to 1100℃.

[0026] In a preferred embodiment of the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, the size of the difficult-to-weld high-temperature alloy additive manufacturing specimen is related to its hardness, micromorphology and metallography.

[0027] In a preferred embodiment of the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, among the laser powder bed melting technical parameters, the laser scanning path includes an offset scanning path, a strip path or a grid path, the scanning speed is 200 mm / s to 2000 mm / s, the scanning spacing is 50 mm to 200 mm, the layer thickness is in the micron to millimeter range, and the rotation speed is 67°C or 90°C.

[0028] In a preferred embodiment of the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, the scanning pitch is related to the overlap rate of the light spots, the offset scanning path includes a Z-shaped path, and the scanning path, scanning speed, and rotation speed of the ultrafast laser are the same as the scanning path, scanning speed, and rotation speed of the additive laser.

[0029] In a preferred embodiment of the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, the laser shock peening parameters include a pulse width of picosecond and femtosecond scales; a wavelength of 1064 nm, a frequency of 10 kHz to 2 MHz, a spot diameter of 40 μm to 350 μm, and an overlap rate of 50% to 75%.

[0030] In a preferred embodiment of the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, the predetermined temperature of the substrate does not exceed 200° C.; and the wind field speed is 2.6 mm / s.

[0031] In a preferred embodiment of the ultrafast laser composite additive manufacturing method for a difficult-to-weld high-temperature alloy, mechanical processing includes a first step of wire cutting or electric spark cutting, a second step of cutting or lathe processing to maintain surface smoothness and flatness, and heat treatment includes annealing, normalizing, quenching, solution treatment or aging treatment.

[0032] A manufacturing system for implementing the method includes: A workbench comprising, substrate, which supports the difficult-to-solder high-temperature alloy, a working chamber, which seals the substrate and provides an argon protective atmosphere, An additive laser, which prints difficult-to-weld high-temperature alloys in the working chamber based on laser powder bed fusion technology parameters, Ultrafast laser, which prints difficult-to-weld high-temperature alloys based on laser shock peening parameters in the working chamber, and additive laser and ultrafast laser perform layer-by-layer strengthening or follow-up strengthening printing to obtain difficult-to-weld high-temperature alloy forging specimens, Machining unit, which cuts the hard-to-weld high-temperature alloy forging print specimen from the substrate and keeps the surface flat, The heat treatment unit heat treats the difficult-to-weld high-temperature alloy forged printed specimen to eliminate internal defects and obtain a difficult-to-weld high-temperature alloy additive specimen.

[0033] In one embodiment, the pulse energy is 100 uJ~2.5 mJ.

[0034] In one embodiment, the method comprises the following steps: S1: Determine the size of the difficult-to-weld high-temperature alloy additive test piece, determine the particle size and physical parameters of the high-temperature alloy, such as element content and melting point, and select the high-temperature alloy material that meets the processing purpose; S2: Determine the laser powder bed fusion (L-PBF) and laser shock peening (LSP) parameters in the slicing software. L-PBF parameters include the laser scanning path, scanning speed, layer thickness, scanning spacing, and rotation angle. LSP parameters include pulse energy, pulse width, wavelength, frequency, spot diameter, overlap ratio, scanning path, scanning spacing, and rotation angle. S3: Preparation for high-temperature alloy equipment printing. The printing process requires an oxygen-free atmosphere, so argon is selected as the shielding gas. This process requires setting the following parameters, including substrate temperature, oxygen content, wind speed, etc. Printing can only be performed when all conditions are met. S4: Import the slice number model into the device, and the ordinary additive laser and the strengthening laser work simultaneously to print. This step requires setting the interval time between the two laser beams. Two printing methods are used: layer-by-layer strengthening and follow-up strengthening. S5: Post-processing of the hard-to-weld high-temperature alloy forged printed specimens. Post-processing consists of two steps: the first is machining to cut the high-temperature alloy specimen from the substrate and ensure surface flatness; the second is heat treatment of the high-temperature alloy specimen to eliminate internal defects, improve the specimen's microstructure, and enhance its performance.

[0035] In the step S1, the difficult-to-weld high-temperature alloy is mainly nickel-based high-temperature alloy, including but not limited to Mar-M247, GH4169, K438, etc. The high-temperature alloy is in powder form with a particle size of 10μm~100μm; the alloying elements are mainly Ni, and also include Cr, Ti, Al, W, Mo and other elements. The working temperature of different high-temperature alloys varies from 600℃ to 1100℃, which needs to be determined according to the physical properties of each high-temperature alloy.

[0036] The size of the difficult-to-weld high-temperature alloy specimen in step S1 can be determined according to the test performance requirements. For example, hardness, micromorphology, metallography, etc. The specimen size can be set to 10mm 10mm 10mm; if mechanical properties testing is required, refer to the relevant national standards. For example, metallography can be performed according to GB / T13298-2015 Metal Microstructure Test Methods, hardness tests can be performed according to GB 2024-2019-T-610, etc. Mechanical properties include durability tests according to GB 6395-1986 "Metals High-Temperature Tensile Test Methods," high-temperature fatigue tests according to GB / T 3075-2021 "Metallic Materials Fatigue Test - Axial Force Control Methods," and creep tests according to GB / T 2039-2012 "Metallic Materials Uniaxial Tension Creep Test Methods."

[0037] Regarding the L-PBF parameters in the S2 step, the laser scanning path is in a "Z" shape, which can also be called an "S" shape, also known as offset scanning; other scanning paths include strip-shaped, checkerboard-shaped, etc.; the scanning speed is 200mm / s~2000mm / s; the scanning spacing can be determined according to the overlap rate, generally set to 50mm~200mm; the layer thickness can be from micron level to millimeter level, and can be specifically set according to the specimen size, including but not limited to, for example, the height dimension of the K438 additive specimen is 10mm, and the layer thickness can be selected as 0.05mm, so 200 layers need to be printed.

[0038] In step S2, the LSP parameters for laser energy are set based on the laser type. The pulse width is also determined based on the laser type and can be in picosecond (ps) or femtosecond (fs) scales. The wavelength is set to 1064 nm. Pulse energy can be in μj, mj, or j scales. The spot diameter is set in the range of 40 μm to 350 μm. The overlap ratio, which refers to the overlap between the spots, can be set between 50% and 75%.

[0039] The scanning path and scanning speed in the LSP parameters in step S2 can be consistent with the additive manufacturing path, and can also be set as needed; the frequency can be set from 10 kHz to 2 MHz. The rotation angle is the angle between the starting point of the next layer and the previous layer after each layer is printed, and is generally set to 67° or 90°.

[0040] Step S3 is the preparation for high-temperature alloy printing. Ensure inert gas protection throughout the printing process, using argon as the equipment shielding gas. The oxygen content must be controlled below 0.3wt% for printing. The substrate temperature is set based on the equipment temperature setting and basic temperature resistance, including but not limited to 316L substrate temperatures not exceeding 200°C. The wind speed is required to blow out impurities and ablation gases, and is also determined based on the material. For difficult-to-weld high-temperature alloys, the wind speed can be set at 2.6mm / s.

[0041] The model in step S4 refers to the printed model, which can be a block object, a cylindrical object, an actual printed component model, etc. The interval between the ordinary additive laser and the intense fast laser can be set according to experimental needs, and the interval time is ≥ 0s.

[0042] The two printing modes in step S4 are layer-by-layer enhancement and follow-up enhancement. Layer-by-layer enhancement involves the ultrafast laser performing enhancement after conventional additive printing completes a layer. The time interval between the two laser beams is based on the time it takes for the conventional additive laser to complete a layer. Follow-up enhancement, however, sets the interval based on the distance between the two laser beams. It can be set to 0s for simultaneous output; other time intervals can also be set. The two laser beams maintain the same path, with conventional additive printing and the enhancement laser following behind to enhance the print.

[0043] In step S5, the high-temperature alloy forging specimen is post-processed. The post-processing mainly includes two steps: machining and heat treatment.

[0044] Machining is a two-step process. The first step involves sorting the high-temperature alloy additive parts, which requires cutting technology. Wire cutting is typically used, but EDM can also be used. However, EDM can easily generate oxides, which can interfere with analysis. The second step involves processing the cut additive parts. This includes, but is not limited to, machining or lathing if the surface is rough, ultimately ensuring the surface finish and flatness of the high-temperature alloy additive parts.

[0045] Heat treatment of difficult-to-weld high-temperature alloy additive manufacturing parts. Heat treatment methods for high-temperature alloy additive manufacturing specimens vary depending on the material type. These include annealing, normalizing, quenching, solution treatment, and aging. These procedures are carried out in accordance with national standards GB / T12603-2005, "Metal Heat Treatment Process Code," and GB / T39247-2020, "Specifications for Heat Treatment Processes Between Metals in Additive Manufacturing." Finally, cooling is performed to obtain qualified specimens.

[0046] Example 1: Using K438 as an example, this paper describes a method for high-performance ultrafast laser composite additive manufacturing of difficult-to-weld high-temperature alloys. The specific implementation steps are as follows: S1: Select K438 nickel-based high-temperature alloy powder with a particle size of 18μm~53μm, of which the Cr element content is 15.7%~16.3%, the W element content is 2.4%~2.8%, the Al element content is 3.2%~3.7%, the Ti element content is 3.00%~3.50%, and also includes Mo, Mn, C, Nb, Ta and other elements.

[0047] After determining the high-temperature alloy powder, determine the size of the high-temperature alloy additive test piece; the print size in this example is 56mm 16mm 3mm specimen. Both S1s are the contents of the above S1 step. Of course, you can merge them according to the general format and requirements of patent applications. The following S2 step is the same.

[0048] S2: Based on the properties of K438 alloy powder, L-PBF parameters were determined. The laser scanning path was in a "Z" shape, the scanning speed was set to 1000 mm / s, the layer thickness was 0.05 mm, 60 layers were required to print the sample, and the scanning interval was set to 50 μm.

[0049] Determine the LSP parameters, keeping the scanning path, scanning speed, and scanning spacing consistent with the L-PBF parameters. For picosecond lasers, set the pulse width to 1 ps to 50 ps, ​​the laser energy to 100 μJ to 2.5 mJ, the spot diameter to 40 μm to 200 μm, and the overlap ratio to 50% and 75%. For femtosecond lasers, set the pulse width to 0 to 1 ps, the laser energy to 100 μJ to 10 mJ, the spot diameter to 40 μm to 350 μm, and the overlap ratio to 50%.

[0050] S3: Preparation of the high-temperature alloy forging printing equipment: Spread the K438 nickel-based high-temperature alloy powder evenly on the workbench; preheat the substrate to 150°C and install the scraper; adjust the laser printing position to ensure that it acts on the substrate; set the wind field speed to 2.6mm / s, close the hatch, turn on the protective gas to ensure that the oxygen content is less than 0.3wt%, and wait for the equipment to meet the setting conditions.

[0051] S4: Slice the K438 nickel-based superalloy specimen, then import the model into the instrument. Open the instrument software and load the model. Select follow-up strengthening based on the experimental requirements. Set the interval between the conventional additive laser and the ultrafast laser to 0-1000ms.

[0052] S5: Post-processing of the K438 superalloy specimens involves wire cutting to separate the specimen from the substrate. Cutting and grinding are then used to ensure a smooth surface. Heat treatment is then performed using a combination of solution treatment and aging. Solution treatment is performed at 1120°C for 2 hours, followed by cooling under an argon atmosphere, then at 845°C for 24 hours, followed by air cooling.

[0053] Example 2: This paper uses GH4169 as an example to illustrate a method for high-performance ultrafast laser composite additive manufacturing of difficult-to-weld high-temperature alloys. The specific implementation steps are as follows: S1: Select K438 nickel-based high-temperature alloy powder with a particle size of 18μm~53μm, of which the Cr element content is 17%~21%, the Mo element content is 2.8%~3.3%, the Al element content is 0.3%~0.7%, the Ti element content is 0.75%~1.15%, the Ni element content is 50%~55%, and other elements include C, Nb, Ta, etc.

[0054] After determining the high-temperature alloy powder, determine the size of the high-temperature alloy additive test piece; the print size in this example is 56mm 16mm 3mm specimen.

[0055] S2: Based on the properties of GH4169 alloy powder, L-PBF parameters were determined. The laser scanning path was strip-shaped, the scanning speed was selected to be 1250 mm / s, and the layer thickness was 0.04 mm. The former sample had a total of 1400 printed layers, and the scanning pitch was set to 35 μm.

[0056] Determine the LSP parameters, keeping the scanning path, scanning speed, and scanning spacing consistent with the L-PBF parameters. For picosecond lasers, set the pulse width to 1 ps to 50 ps, ​​the laser energy to 100 μJ to 2500 μJ, the spot diameter to 40 μm to 200 μm, and the overlap ratio to 50% and 75%. For femtosecond lasers, set the pulse width to 0 to 1 ps, the laser energy to 100 μJ to 10 mJ, the spot diameter to 40 μm to 350 μm, and the overlap ratio to 50% and 75%.

[0057] S3: Preparation of the high-temperature alloy forging printing equipment: Spread the GH4169 nickel-based high-temperature alloy powder evenly on the workbench; preheat the substrate to 150°C and install the scraper; adjust the laser printing position to ensure that it acts on the substrate; set the wind field speed to 2.6mm / s, close the hatch, turn on the protective gas to ensure that the oxygen content is less than 0.25wt%, and wait for the equipment to meet the setting conditions.

[0058] S4: Slice the GH4169 nickel-based superalloy specimen, then import the model into the instrument. Open the instrument software and load the model. Select follow-up strengthening based on the experimental requirements. Set the interval between the conventional additive laser and the ultrafast laser to 0-1000ms.

[0059] S5: Post-processing of the GH4169 superalloy specimens involves wire cutting to separate the specimen from the substrate. Cutting and grinding are then used to ensure a smooth surface. Heat treatment is then performed using a combination of solution treatment and aging. Solution annealing is performed at 1050°C for 1 hour, followed by water quenching. Aging is performed at 850°C for 8 hours, followed by cooling.

[0060] Example 3: This paper uses In738 as an example to illustrate a method for high-performance ultrafast laser composite additive manufacturing of difficult-to-weld high-temperature alloys. The specific implementation steps are as follows: S1: Select K438 nickel-based high-temperature alloy powder with a particle size of 18μm~53μm, of which the Cr element content is 16.04%, the Co element content is 8.59%, the W element content is 2.49%, the Nb element content is 0.99%, the Ti element content is 3.41%, and also includes Mo, Mn, C, Ni, Ta and other elements.

[0061] After determining the high-temperature alloy powder, determine the size of the high-temperature alloy additive test piece; the print size in this example is 10mm 10mm 10mm specimen.

[0062] S2: Based on the properties of the In738 alloy powder, the L-PBF parameters were determined. The laser scanning path was a checkerboard pattern, with a scanning speed of 1200 mm / s, a layer thickness of 0.04 mm, 250 layers of printing required, and a scan interval of 100 μm.

[0063] Determine the LSP parameters, keeping the scanning path, scanning speed, and scanning spacing consistent with the L-PBF parameters. For a picosecond laser, set the pulse width to 13.05 ps, the laser energy to a range of 100 μJ to 2.5 mJ, the spot diameter to 60 μm, and the overlap ratio to 90%.

[0064] S3: Preparation of the high-temperature alloy forging printing equipment: Spread the In738 nickel-based high-temperature alloy powder evenly on the workbench; preheat the substrate to 150°C and install the scraper; adjust the laser printing position to ensure that it acts on the substrate; set the wind field speed to 2.6mm / s, close the hatch, turn on the protective gas to ensure that the oxygen content is less than 0.3wt%, and wait for the equipment to meet the setting conditions.

[0065] S4: Slice the In738 nickel-based superalloy specimen, then import the model into the instrument. Open the instrument software and load the model. Select follow-up strengthening based on the experimental requirements. Set the interval between the conventional additive laser and the ultrafast laser to 0-5000ms.

[0066] S5: Post-processing of the In738 superalloy specimens involved wire cutting to separate the specimen from the substrate. Cutting and grinding were then used to ensure a smooth surface. Heat treatment followed, using a combination of solution treatment and aging. Hot isostatic pressing (HIPP) was performed at 1200°C and 120 MPa for 240 minutes. The specimens were then aged at 1120°C for 2 hours and finally at 845°C for 24 hours.

[0067] like Figure 4As shown, a large amount of carbides and unmelted particles precipitated on the surfaces of Examples 2 and 3, resulting in a high surface roughness, while the surface of Example 1 was smoother and had only a small amount of precipitates. This indicates that Example 1 has better process parameters and surface morphology than the other examples.

[0068] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments and application fields. The above-mentioned specific embodiments are merely illustrative and instructive, and are not restrictive. A person skilled in the art, guided by this specification and without departing from the scope of protection of the claims of the present invention, may also devise various forms, all of which fall within the scope of protection of the present invention.

Claims

1. An ultrafast laser composite additive manufacturing method for difficult-to-weld high-temperature alloys, characterized in that: The steps include: Step S1: determining the particle size and physical parameters of the difficult-to-weld high-temperature alloy, and determining the size of the difficult-to-weld high-temperature alloy additive test piece to be manufactured based on the particle size and physical parameters of the difficult-to-weld high-temperature alloy, wherein the physical parameters include element content and melting point; Step S2: Determine laser powder bed fusion technical parameters and laser shock peening parameters based on the particle size and physical parameters of the difficult-to-weld high-temperature alloy. The laser powder bed fusion technical parameters include the laser scanning path, scanning speed, layer thickness, scanning spacing of the additive laser, and the rotation angle between the starting point of the next layer and the angle of the previous layer after each layer is printed. The laser shock peening parameters include the pulse energy, pulse width, wavelength, frequency, spot diameter, overlap rate, scanning path, scanning spacing of the ultrafast laser, and the rotation angle between the starting point of the next layer and the angle of the previous layer after each layer is printed. Step S3: The difficult-to-weld high-temperature alloy is laid flat on a workbench and prepared for printing based on the size of the difficult-to-weld high-temperature alloy additive manufacturing specimen to be manufactured. The substrate is preheated to a predetermined temperature, the laser printing position is adjusted, the wind speed is set, the hatch is closed, and the argon shielding gas is turned on to ensure that the oxygen content is less than 0.3wt%. Step S4: The additive laser and the ultrafast laser perform layer-by-layer strengthening or follow-up strengthening printing to obtain a forged specimen of a difficult-to-weld high-temperature alloy. In the layer-by-layer strengthening, the additive laser prints a layer and then the ultrafast laser performs strengthening. The time interval between the additive laser and the ultrafast laser is based on the time it takes for the additive laser to complete a layer. In the follow-up strengthening, the paths of the additive laser and the ultrafast laser are kept consistent. The additive laser prints and the ultrafast laser follows to perform strengthening. The interval time is set according to the distance between the additive laser and the ultrafast laser, and the interval time is ≥ 0s. Step S5: The difficult-to-weld high-temperature alloy forged printed specimen is subjected to mechanical processing and heat treatment to obtain a difficult-to-weld high-temperature alloy additive specimen, wherein the difficult-to-weld high-temperature alloy forged printed specimen is cut from the substrate by mechanical processing while keeping the surface flat, and then the difficult-to-weld high-temperature alloy additive specimen is obtained by heat treatment to eliminate internal defects.

2. The ultrafast laser composite additive manufacturing method for difficult-to-weld high-temperature alloys according to claim 1, characterized in that: Preferably, the total content of aluminum and titanium in the difficult-to-weld high-temperature alloy exceeds 5 wt %, and the ultrafast laser includes a picosecond laser and a femtosecond laser.

3. The ultrafast laser composite additive manufacturing method for difficult-to-weld high-temperature alloys according to claim 1, characterized in that: The difficult-to-weld high-temperature alloy is in powder form with a particle size of 10μm~100μm; the difficult-to-weld high-temperature alloy includes Ni, Cr, Ti, Al, W and Mo alloy elements, and the operating temperature of the difficult-to-weld high-temperature alloy is 600℃~1100℃.

4. The ultrafast laser composite additive manufacturing method for difficult-to-weld high-temperature alloys according to claim 1, characterized in that: The dimensions of difficult-to-weld high-temperature alloy additive specimens are related to their hardness, micromorphology, and metallography.

5. The ultrafast laser composite additive manufacturing method for difficult-to-weld high-temperature alloys according to claim 1, characterized in that: Among the technical parameters of laser powder bed fusion, the laser scanning path includes offset scanning path, strip path or grid path, the scanning speed is 200mm / s~2000mm / s, the scanning spacing is 50mm~200mm, the layer thickness is from micron to millimeter level, and the rotation speed is 67°C or 90°C.

6. The ultrafast laser composite additive manufacturing method for difficult-to-weld high-temperature alloys according to claim 5, characterized in that: The scanning pitch is related to the overlap rate of the overlap rate between the light spots, the offset scanning path includes a zigzag path, and the scanning path, scanning speed and rotation speed of the ultrafast laser are the same as the scanning path, scanning speed and rotation speed of the additive laser.

7. The ultrafast laser composite additive manufacturing method for difficult-to-weld high-temperature alloys according to claim 1, characterized in that: Among the laser shock peening parameters, the pulse width is in the picosecond and femtosecond scales; the wavelength is 1064nm, the frequency is 10KHz~2MHz, the spot diameter is 40μm~350μm; and the overlap rate is 50%-75%.

8. The ultrafast laser composite additive manufacturing method for difficult-to-weld high-temperature alloys according to claim 1, characterized in that: The predetermined temperature of the substrate does not exceed 200° C.; the wind speed is 2.6 mm / s.

9. The ultrafast laser composite additive manufacturing method for difficult-to-weld high-temperature alloys according to claim 1, characterized in that: Machining includes the first step of wire cutting or electric spark cutting, the second step of cutting or lathe processing to maintain surface finish and flatness, and heat treatment including annealing, normalizing, quenching, solution treatment or aging treatment.

10. A manufacturing system for implementing the method according to any one of claims 1 to 9, characterized in that: It includes, A workbench comprising, substrate, which supports the difficult-to-solder high-temperature alloy, a working chamber, which seals the substrate and provides an argon protective atmosphere, An additive laser, which prints difficult-to-weld high-temperature alloys in the working chamber based on laser powder bed fusion technology parameters, Ultrafast laser, which prints difficult-to-weld high-temperature alloys based on laser shock peening parameters in the working chamber, and additive laser and ultrafast laser perform layer-by-layer strengthening or follow-up strengthening printing to obtain difficult-to-weld high-temperature alloy forging specimens, Machining unit, which cuts the hard-to-weld high-temperature alloy forging print specimen from the substrate and keeps the surface flat, The heat treatment unit heat treats the difficult-to-weld high-temperature alloy forged printed specimen to eliminate internal defects and obtain a difficult-to-weld high-temperature alloy additive specimen.

Images