A method of additive manufacturing of a high temperature alloy process optimization

Abstract

The application provides a method for optimizing an additive manufacturing high-temperature alloy process, and relates to the field of metal additive manufacturing, and comprises the following steps: dividing a printing model of the additive manufacturing high-temperature alloy into multiple regions, and printing the multiple regions by using multiple preset process parameter groups respectively; and respectively characterizing and testing the microstructure and mechanical properties of the multiple regions after printing is completed, so as to screen the process parameters of the additive manufacturing high-temperature alloy. By dividing into multiple regions, printing the multiple regions by using multiple preset process parameter groups respectively, one-time forming of multiple process parameter group combinations in a single sample is realized, and the efficiency during process parameter screening is greatly improved; after printing is completed in one region, a next region to be printed is printed after a set interval time, so as to weaken the influence of subsequent heat input on the microstructure and performance characterization results of the printed region.

Description

Technical Field

[0001] This invention belongs to the field of metal additive manufacturing technology, specifically relating to a method for optimizing the additive manufacturing process of nickel-based superalloys by achieving efficient screening of process parameters through partitioned integrated printing and regional thermal interference control. Background Technology

[0002] Currently, key industrial sectors such as aerospace, defense equipment, and energy power are placing higher demands on the comprehensive performance of metal structural components, particularly in terms of lightweighting, integration, and high reliability. Simultaneously, the increasing demand for integrated manufacturing of large and complex components poses significant challenges to traditional manufacturing processes in terms of shape freedom, material utilization, and microstructure control. Metal additive manufacturing technology is a layer-by-layer forming technology based on digital models and powered by high-energy beams (such as lasers or electron beams). It achieves the direct manufacturing of complex components by selectively melting and rapidly solidifying metal powder. Compared to traditional casting, forging, and machining methods, additive manufacturing offers advantages such as no need for molds, high material utilization, short manufacturing cycles, and high structural design freedom. It also possesses the potential for on-demand control of local microstructure and properties, demonstrating broad application prospects in the field of high-performance component manufacturing.

[0003] Nickel-based superalloys are widely used in hot-end critical components such as aero-engines and gas turbines due to their excellent high-temperature strength, creep resistance, and oxidation and corrosion resistance. However, these alloys typically exhibit high alloy element content, narrow solidification temperature ranges, and complex precipitate evolution, leading to high hot cracking susceptibility during additive manufacturing processes such as Selective Laser Melting (SLM). This characteristic not only limits the density and stability of the formed product but also significantly increases the difficulty of optimizing process parameters. To obtain a microstructure with high density, low defect rate, and satisfactory performance, it is necessary to systematically optimize key process parameters such as layer thickness, laser power, scanning speed, scanning track spacing, and scanning strategy. However, the effective process window for nickel-based superalloys is usually quite narrow, and different parameter combinations have a significant impact on melt pool stability, grain morphology, microstructure evolution, and subsequent properties, necessitating multi-parameter synergistic screening within a larger parameter space.

[0004] In existing technologies, the optimization of process parameters for additive manufacturing of nickel-based superalloys often adopts a step-by-step experimental approach of "single parameter - single sample," meaning that each set of parameters corresponds to an independent printed sample. However, this step-by-step experimental method for optimizing the process is inefficient. Summary of the Invention

[0005] Therefore, the present invention provides a method for optimizing the additive manufacturing process of high-temperature alloys. The main purpose is to provide a method for optimizing the additive manufacturing process of nickel-based high-temperature alloys to solve the problems of low experimental efficiency, significant batch effect, and difficulty in reliably comparing different parameter combinations in the existing process parameter screening process.

[0006] To achieve the above objectives, the present invention provides a method for optimizing the additive manufacturing process of high-temperature alloys, comprising the following steps:

[0007] Step 1): Divide the additive manufacturing high-temperature alloy printing model into multiple regions, and print each region using a preset set of process parameters;

[0008] Step 2): The microstructure and mechanical properties of multiple regions after printing are characterized and tested to screen the process parameters for the additive manufacturing of the high-temperature alloy.

[0009] Furthermore, in step 1): when printing adjacent first and second regions consecutively, after the printing of the first region is completed, a set time interval is set to allow the temperature of the first region to drop below a preset cooling threshold before printing the second region.

[0010] Preferably, the additive manufacturing high-temperature alloy is a nickel-based high-temperature alloy; the preset cooling threshold is 50–200 °C below the γ′ phase solution temperature;

[0011] Preferably, the set time is 5 to 50 seconds; more preferably, it is 10 to 20 seconds.

[0012] Furthermore, in step 1):

[0013] A spatially offset scanning strategy is adopted for adjacent areas so that the scan lines of adjacent areas are spatially offset by a set amount, which is 0.3 to 1.5 times the spacing between scan tracks;

[0014] Preferably, the set offset is 0.5 to 1.0 times the scanning track spacing.

[0015] Furthermore, when printing adjacent first and second regions, after the first region is printed, scanning is performed using one or more of the following methods:

[0016] a. Perform a preheating scan on the side of the boundary between the first and second regions that is closer to the first region; preferably, the laser power of the preheating scan is 50-70% of the laser power used for printing the first region;

[0017] b. In the second region, the laser power of the first 2 to 5 scan lines near the boundary between the first and second regions decreases sequentially; preferably, the decrease is 10% to 40%.

[0018] c. Adjust the scanning direction of the second region so that the heat conduction direction of the molten pool points towards the first region.

[0019] Furthermore, in step 1): when printing adjacent first and second regions consecutively, an interval structure is set between the first and second regions.

[0020] Furthermore, the filling configuration of the spacer structure is one or more of a dot matrix structure, a honeycomb structure, and a discontinuous grid; and / or, the filling density of the spacer structure is 10% to 80%, preferably 20% to 60%.

[0021] Furthermore, the spacing structure includes a first segment and a second segment; wherein the first segment is adjacent to the first region and is printed using the same set of process parameters as the first region; the second segment is adjacent to the second region and is printed using the same set of process parameters as the second region.

[0022] Furthermore, in step 1), the process parameter set includes one or more of the following: layer thickness, laser power, scanning speed, scanning track spacing, and scanning strategy.

[0023] Preferably, the layer thickness is 0.02–0.12 mm; the laser power is 140–400 W; the scanning speed is 700–1100 mm / s; the scanning track spacing is 0.06–0.1 mm; and the scanning strategy is long straight-line scanning, checkerboard scanning, or spiral filling scanning. More preferably, the additive manufacturing high-temperature alloy is IN738 nickel-based high-temperature alloy; when the powder particle size of IN738 nickel-based high-temperature alloy is 15–53 μm, a layer thickness of 0.02–0.06 mm is used; when the powder particle size of IN738 nickel-based high-temperature alloy is 53–106 μm, a layer thickness of 0.06–0.12 mm is used.

[0024] To achieve the above objectives, the present invention provides the following technical solution: the model to be printed is divided into multiple construction regions, and different construction regions correspond to different sets of process parameters; after printing of a construction region is completed, the superposition of thermal effects between regions is reduced by setting region switching time, spatial misalignment scanning and boundary thermal guidance control;

[0025] Furthermore, there is one parameter that differs in the process parameter groups corresponding to adjacent regions.

[0026] Furthermore, in step 1), parameters in the process parameter group are selected based on the volumetric energy density model; where Ev = P / (v × h × t); and Ev is the volumetric energy density, in J / mm². 3 P is the laser power in W; v is the scanning speed in mm / s; h is the scanning track spacing in mm; t is the layer thickness in mm.

[0027] Preferably, Ev is 10–500 J / mm 3 Further preferred is 50–200 J / mm 3 .

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] 1. By constructing multiple process parameter regions in the same printing task, multiple sets of process parameters can be formed and compared simultaneously, significantly improving process screening efficiency and reducing sample quantity, material consumption, and equipment time.

[0030] 2. By setting area switching delay, spatial misalignment scanning, and boundary thermal guidance control, thermal interference between adjacent areas can be reduced, and the reliability of tissue and performance comparison between areas with different parameters can be improved.

[0031] 3. This invention can establish a parameter-microstructure-property mapping relationship in the same reference sample, and is applicable to precipitation-strengthened nickel-based superalloys, and is preferably applicable to the screening and optimization of process windows for IN738 nickel-based superalloys.

[0032] 4. By setting dense or non-dense intervals between adjacent parameter regions, the influence on the temperature field and tissue response of the main test area can be reduced, while improving the identifiability, traceability and subsequent sampling positioning accuracy of different parameter regions of high-throughput samples, thereby reducing the risk of sample confusion and improving the reliability of the parameter-tissue-performance mapping relationship. Attached Figure Description

[0033] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the overall process of the method of the present invention;

[0035] Figure 2 A schematic diagram illustrating the distribution of different process parameter regions along the construction direction (Z-axis);

[0036] Figure 3 A schematic diagram illustrating the division of the XY plane into different printing areas to achieve multi-parameter printing;

[0037] Figure 4 These are model diagrams of the areas printed using different parameters in Example 1;

[0038] Figure 5 This is a schematic diagram illustrating the relationship between process parameters, microstructure, and properties.

[0039] Figure 6 This is a diagram showing defects (such as cracks and holes) corresponding to some parameter areas in Example 1;

[0040] Figure 7 The relationship between the tissue images and energy density under an optical microscope of the printed area cross-section using different parameters in Example 1;

[0041] Figure 8 The relationship between density and energy density under an optical microscope for the cross-section of the printed region using different parameters in Example 1;

[0042] Figure 9 This is a model diagram of the printing area with different parameters in Example 2;

[0043] Figure 10 These are tissue images under an optical microscope (OM) of the printed area cross-sections using different parameters in Example 2;

[0044] Figure 11 These are comparative images of the microstructure under OM (Original Microstructure) of the printed area cross-section using different parameters in Example 2;

[0045] Figure 12 These are comparative images of tissues under EBSD printed with different parameters in Example 2;

[0046] Figure 13 To illustrate the structure of the sample used in Comparative Example 1, existing methods were employed to print the sample's structural diagram.

[0047] Figure 14 The model diagram shown in Comparative Example 2 is printed using blocks with different layer thicknesses.

[0048] Figure 15 To print a model diagram of non-dense regions between adjacent areas using different parameters. Detailed Implementation

[0049] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0050] Existing single-parameter, single-sample methods are not only inefficient and consume significant amounts of materials and time, but also prone to introducing systematic errors due to batch sample preparation, affecting the accuracy of parameter comparisons. This problem is particularly pronounced in the construction of small-scale additive manufacturing equipment with limited space. Therefore, there is an urgent need for an efficient process screening method that can integrate multiple sets of process parameters in the same component or sample to achieve parallel comparison of microstructure and properties under different parameter conditions, thereby accelerating the process optimization and engineering application of difficult-to-machine materials such as nickel-based superalloys in the field of additive manufacturing. The specific solution of this invention is as follows:

[0051] A method for optimizing the additive manufacturing process of high-temperature alloys includes the following steps:

[0052] Step 1): Divide the additive manufacturing high-temperature alloy printing model into multiple regions, and print each region using a preset set of process parameters;

[0053] Step 2): The microstructure and mechanical properties of multiple regions after printing are characterized and tested to screen the process parameters for the additive manufacturing of the high-temperature alloy.

[0054] This invention divides the printed model into multiple regions, and prints each region using a set of preset process parameters, thereby achieving one-time forming of multiple sets of process parameters within a single sample, which greatly improves the efficiency of process parameter selection; at the same time, it significantly reduces the number of samples, material consumption, and equipment time.

[0055] When dividing the printed model into regions, it can be done along the construction direction (Z direction) and / or along the same printing layer plane (XY direction).

[0056] For models divided along the same printing layer plane (XY direction), non-adjacent areas can be printed continuously. However, this method requires frequent switching between non-adjacent areas, increasing the idle travel distance and affecting the efficiency of printing and process parameter selection. Conversely, for models divided along the build direction, adjacent areas must be printed continuously.

[0057] Therefore, in some embodiments, when printing adjacent first and second regions consecutively, after the printing of the first region is completed, a set time interval is set to allow the temperature of the first region to drop below a preset cooling threshold before printing the second region; preferably, the additive manufacturing high-temperature alloy is a nickel-based high-temperature alloy; the preset cooling threshold is 50 to 200 °C below the γ′ phase solid solution temperature; preferably, the set time is 5 to 50 seconds; more preferably, it is 10 to 20 seconds.

[0058] By selecting the above temperature range, the printed area (first area) can enter a temperature range that is insensitive to the redissolution of the γ′ phase and the further evolution of the microstructure before being heated again, thus balancing the stability of the structure and the printing efficiency.

[0059] In some implementations, when printing adjacent first and second regions consecutively, an interval structure is set between the first and second regions. On the one hand, this can reduce the superposition of thermal effects between adjacent regions, thereby avoiding the impact of the superposition of thermal effects on the microstructure and properties of the (printed area). On the other hand, it can be used to distinguish adjacent regions, enabling accurate sampling of the corresponding regions when performing microstructure and mechanical property characterization.

[0060] like Figure 15 As shown, the aforementioned spacing structure can adopt either a dense spacing paradigm or a non-dense spacing paradigm. The dense spacing paradigm involves setting a dense transition zone or transition layer between adjacent regions, with a preferred thickness of 0.3–0.5 mm. It is preferably used for continuous regions divided along the construction direction to ensure forming continuity and interlayer stability. The non-dense spacing paradigm involves setting a non-dense region between adjacent regions, preferably used for dividing multi-parameter high-throughput regions within the same layer plane to improve region identification, traceability, and the accuracy of subsequent sampling and positioning.

[0061] In this invention, the main test areas (such as the first and second areas) are preferably formed into a continuous solid structure using a dense printing method, thereby constituting a continuous heat conduction path. The non-dense areas between adjacent main test areas are preferably formed using low-volume-fraction topologies such as lattice structures, honeycomb structures, or discontinuous grid structures, thereby constituting a discontinuous heat conduction path. Because the continuous solid skeleton is reduced in the non-dense areas, the continuous heat conduction and the superposition of molten pool heat input between adjacent test areas can be reduced. Therefore, by setting the main test areas as dense areas and the area separation structures as non-dense areas, the interference of boundary thermal effects on the microstructure and performance characterization results of the main test areas can be reduced while ensuring area identification.

[0062] Specifically, when the filler density is below 10%, the structural continuity and mechanical integrity of the non-dense area are insufficient, which is not conducive to forming stable and identifiable regional divisions and is prone to local damage during subsequent sample preparation. When the filler density is above 80%, the density difference between the non-dense area and the main test area decreases, and the number of continuous heat conduction paths increases, which is not conducive to reducing thermal crosstalk between adjacent areas. Therefore, limiting the filler density to 10%–80%, preferably 20%–60%, can reduce continuous heat conduction and heat accumulation at the boundary while ensuring regional identifiability and printing stability. From the perspective of heat conduction, the reduction of the filler density in the non-dense area corresponds to the reduction of the local relative density, thereby reducing the proportion of continuous solid skeleton and weakening cross-regional heat flow transfer; however, when the filler density is too low, the effective connection between melt channels is insufficient, which will reduce the forming continuity and structural stability of the non-dense area. Therefore, the filler density range defined in this application is not arbitrarily set, but is determined comprehensively based on regional identifiability, structural stability, and thermal effect control.

[0063] The interval structure includes a first segment and a second segment; the first segment is adjacent to the first region and is printed using the same set of process parameters as the first region; the second segment is adjacent to the second region and is printed using the same set of process parameters as the second region. This ensures clear assignment of region parameters and reduces the impact of boundary position parameter confusion on the microstructure and performance evaluation results.

[0064] like Figure 1 As shown, the method for optimizing the additive manufacturing process of high-temperature alloys provided by this invention specifically includes the following steps:

[0065] Parameter combination design → Region division and parameter mapping → Multi-parameter integrated printing → Regional characterization and analysis → Process collaborative evaluation.

[0066] I. Selection of Key Process Parameters and Determination of Process Window

[0067] First, from the process parameters that have a significant impact on the stability of the molten pool and the evolution of the microstructure during the additive manufacturing process, key parameters that need to be screened and optimized are selected. These key parameters include: layer thickness, laser power, scanning speed, scanning track spacing, and scanning strategy.

[0068] Specifically, the key process parameters are uniformly constrained using a volumetric energy density model, expressed as: Ev = P / (v×h×t); where Ev is the volumetric energy density, in J / mm². 3 P is the laser power in W; v is the scanning speed in mm / s; h is the scanning track spacing in mm; t is the layer thickness in mm.

[0069] Before formally conducting multi-parameter regional integrated printing, large-span tests were performed on the parameters through preliminary experiments to determine the volumetric energy density window Ev to be 10–500 J / mm². 3 Preferably, the J / mm² is 50–200 J / mm². 3 To determine the effective process window boundaries for each parameter. These effective process window boundaries include at least: a lower limit of non-melting where insufficient energy input results in incomplete powder melting; and an upper limit of energy input that leads to splashing, spheroidizing, or overheating.

[0070] In this invention, the layer thickness t is 20–120 μm (0.02–0.12 mm); the laser power P is 140–400 W; the scanning speed v is 700–1100 mm / s; the scanning track spacing h is 60–100 μm (0.06–0.1 mm); and the scanning strategies are long straight line scanning, checkerboard scanning, and spiral filling scanning.

[0071] II. Systematic Division and Parameter Mapping of Constructing Regions

[0072] In the slicing stage (3D modeling stage), based on the combination of process parameters designed in step 1, the printed component is divided into multiple construction regions in the construction direction (Z direction) and / or the same printing layer plane (XY direction), and each parameter combination is mapped to the corresponding region (that is, the printed model is divided into multiple regions).

[0073] In the construction direction, the region is divided according to the principle of single variable to reveal the independent influence of a single process parameter on the evolution of microstructure and properties along the construction direction; within the same printing layer plane, the region is divided according to the principle of gradient distribution to quickly capture the continuous response and abrupt change critical points of microstructure and properties as parameters change.

[0074] The single-variable principle involves fixing all parameters except for a target parameter within a set of process parameters, and only changing the target parameter to analyze its independent influence on the formed microstructure or defect behavior. The gradient distribution principle involves making a certain parameter or volumetric energy density exhibit continuous or stepwise changes within multiple sets of process parameters to analyze the continuous response and abrupt changes in microstructure or properties as a function of parameters (i.e., designing different sets of process parameters for different regions based on the single-variable principle or gradient distribution principle).

[0075] The parameter variation interval between adjacent parameter combinations is set based on the parameter influence sensitivity determined in the preliminary experiment: smaller variation intervals are used for parameters that are highly sensitive to tissue or defects; larger variation intervals are used for parameters that have a milder effect on tissue or defects.

[0076] In some implementations, the component is divided into multiple consecutive build regions along the build direction, each corresponding to a set of process parameter combinations. In multiple consecutively printed layers, all parameters except the target parameter are kept constant, while the target parameter is systematically changed between adjacent regions to reveal the influence of this parameter on the evolution of the microstructure along the build direction, such as... Figure 2 As shown, the deposition sample is divided into n+1 construction regions along the construction direction (Z-axis); among them, in layers 1-5, all parameters except the spacing (target parameter) are kept unchanged (i.e., following the single variable principle mentioned above).

[0077] In another embodiment, regions are divided simultaneously in the build direction and the printing layer plane, creating a parametric distribution structure of layers and regions within the component, such as... Figure 3 As shown, different printing areas are divided in the XY plane; among them, all parameters except scanning speed (target parameter) are kept constant in the same layer (i.e., following the single variable principle mentioned above), and the target parameter gradient changes in adjacent areas of the same layer (i.e., following the gradient distribution principle mentioned above). For example, the difference in scanning speed between area 2 and area 1 in the first layer is 100 mm / s.

[0078] III. Integrated Printing of Multi-Parameter Regions

[0079] During the printing process, based on the defined region division, different combinations of process parameters are used to print each construction region sequentially or in parallel, achieving one-time forming of multiple combinations of process parameters within a single sample. In this application, the relative independence of the microstructure between adjacent parameter regions means that the microstructure characteristics near the boundary of adjacent regions are basically consistent with the main microstructure of the corresponding region, and no significant abnormal microstructure evolution occurs due to the heat input from the printing of adjacent regions.

[0080] The variation intervals between key process parameters are based on the process window boundaries determined by pre-experiments and the sensitivity settings of the parameters' influence on microstructure, so that an energy density gradient with metallurgical significance is formed between adjacent regions, thereby ensuring that each parameter region can provide effective information for the identification of microstructure and properties.

[0081] During actual printing, in order to ensure the relative independence of the organization between adjacent parameter areas, after printing a region, a set time interval is set to allow the temperature of the printed region to drop below a preset cooling threshold; wherein, the preset cooling threshold is 50 to 200°C below the solid solution temperature of the γ′ phase, and the set time is preferably 5 to 50 seconds, and more preferably 10 to 20 seconds.

[0082] The reason for limiting the preset cooling threshold to 50–200°C below the γ′ phase solution temperature is that when the temperature of the printed area is still close to the γ′ phase solution temperature, the heat input introduced by subsequent printing of adjacent areas may still cause significant γ′ re-solution, fluctuations in precipitation state, and further evolution of local microstructure in that area, thereby weakening the microstructure independence between regions with different parameters. However, when the temperature drops to this range, the printed area enters a temperature range that is relatively insensitive to γ′ phase re-dissolution and further evolution of microstructure. Subsequent heat input significantly reduces the disturbance to the microstructure state of this area, which is more conducive to maintaining the microstructure and performance results of this area primarily determined by its own process parameters. If the area temperature only drops to a small range below the γ′ phase solution temperature, subsequent heat input can still easily cause significant microstructure disturbance; if the temperature drops too much, although the microstructure stability is further improved, the area switching waiting time is significantly prolonged, reducing the efficiency of multi-parameter screening. Therefore, limiting the preset cooling threshold to 50–200°C below the γ′ phase solution temperature achieves a balance between microstructure stability and printing efficiency. To evaluate the impact of the aforementioned region switching time and preset cooling threshold on tissue stability and printing efficiency, this invention further employs tissue stability indicators and printing efficiency indicators for comprehensive evaluation.

[0083] Under these conditions, the internal temperature gradient of the printed area is further reduced, and the impact of subsequent printing on its microstructure and performance characterization results can be significantly weakened.

[0084] The adjacent regions adopt a spatially staggered scanning strategy to set the spatial offset between the scan lines of the adjacent regions. The offset is set to 0.3 to 1.5 times the scanning track spacing; the offset is set to 0.5 to 1.0 times the scanning track spacing, thereby reducing the spatial overlap of the molten pool heat input between regions.

[0085] Furthermore, when printing adjacent first and second regions, after the first region is printed, scanning is performed using one or more of the following methods: a) preheating scan of the boundary between the first and second regions, closer to the first region; preferably, the laser power of the preheating scan is 50-70% of the laser power used during the printing of the first region; b) the laser power of the first 2-5 scan lines in the second region, closer to the boundary between the first and second regions, decreases sequentially; preferably, the decrease is 10-40%; c) the scanning direction of the second region is adjusted so that the heat conduction direction of the molten pool points towards the first region. Through the adjustment of the above boundary scanning strategy, the heat from the boundary region diffuses mainly to the already solidified large-volume region, rather than concentrating on the newly printed adjacent region, thereby avoiding thermal interference between the microstructures of the regions.

[0086] During the region switching process, a time-space thermal input decoupling control strategy is adopted. This involves using a skip scanning sequence between adjacent regions, setting a scanning delay time (interval setting time) between high-energy and low-energy regions, and changing the scanning direction or scanning sequence between different regions. This prevents the thermally affected areas of adjacent regions from overlapping significantly, thereby ensuring that the microstructure formed by each parameter region is mainly controlled by its own process parameters.

[0087] To further evaluate the impact of region switching time and preset cooling threshold on tissue stability and printing efficiency, this invention employs a comprehensive evaluation using tissue stability and printing efficiency indicators. The tissue stability indicators include the average KAM difference ΔKAM between the boundary-adjacent region and the main body center region, the microhardness difference ΔHV, and the crack density difference Δρ. crack One or more of the following. The smaller the difference, the closer the microstructure and properties are to the boundary region and the central region of the main body, the weaker the thermal influence superposition between adjacent parameter regions, and the better the relative independence of the microstructure. Printing efficiency indicators include one or more of the following: the number of prints required to complete the same parameter screening task, the number of samples, the number of substrates, the equipment forming time, the number of atmosphere replacements, the protective gas consumption, and the number of parameter groups that can be screened per unit print task. The above indicators can be used to quantitatively evaluate the comprehensive effect of this invention in terms of microstructure stability and parameter screening efficiency.

[0088] IV. Establishing the parameter-organization-performance mapping relationship

[0089] The printed integrated sample is dissected or sampled regionally for microstructural characterization and performance testing. Considering the significant heat-affected zone and the impact of heat treatment, the center of each region (construction area) is preferred for sampling to avoid mutual interference between regions.

[0090] The region designed based on the single variable principle is used to directly establish the independent influence law of a single process parameter on microstructure and properties;

[0091] The region, designed based on the gradient distribution principle, is used to continuously capture the response behavior of tissue and properties as parameters change, and to accurately locate the critical process conditions where abrupt changes occur, thereby obtaining a reliable quantitative mapping relationship between parameters, tissue, and properties.

[0092] The characterization content includes at least one or more of the following: grain size, crystal orientation, crack distribution, porosity, and precipitate phase state.

[0093] V. Evaluation of the Synergistic Effect between Process and Heat Treatment

[0094] Furthermore, the integrated sample with multiple parameters can be subjected to subsequent heat treatment. On the same reference sample, the microstructure response and evolution of regions with different initial printing parameters during the heat treatment process can be evaluated at one time, providing a basis for formulating the optimal "printing-heat treatment" composite process.

[0095] The sample material is preferably IN738 nickel-based high-temperature alloy, and the method can efficiently locate its critical process window with no cracks or low cracks.

[0096] In this design, each process parameter region is constructed within the same alloy sample to avoid thermal stress differences, compositional diffusion, and poor metallurgical bonding issues introduced by dissimilar material substrates, thereby improving the accuracy of parameter comparison.

[0097] The present invention will be further described below with reference to specific embodiments and comparative examples.

[0098] Example 1

[0099] This embodiment provides a method for screening the SLM process window for IN738 alloy based on a combination of XY plane partitioning and construction direction transition control, such as... Figure 4 As shown.

[0100] I. Materials and Equipment

[0101] Powder material: Gas-atomized IN738 nickel-based high-temperature alloy powder; particle size 15–53 μm;

[0102] The chemical composition (wt.%) of the IN738 nickel-based superalloy obtained using this powder material is: Ni-16Cr-8.5Co-1.75Mo-2.6W-3.2Ti-3.5Al-0.1C-0.01B-0.03Zr.

[0103] Printing equipment: SLM forming system (Yb fiber laser, spot diameter approximately 80μm).

[0104] Printing environment: High-purity argon gas protection, oxygen content ≤100ppm; substrate is stainless steel substrate.

[0105] II. Parameter Design and Region Division

[0106] (1) Initial screening and setting of parameters

[0107] Using volumetric energy density model Based on theoretical groundwork, the stable forming energy density window determined in preliminary experiments is 50–200 J / mm². 3 By simultaneously adjusting three key parameters—laser power (P), scanning speed (v), and scanning spacing (h)—the system constructed 125 combinations of process parameters.

[0108] The fixed parameters are set as follows:

[0109] The layer thickness t is 30 μm;

[0110] Scanning strategy: long straight-line scan, interlayer rotation 67°;

[0111] Protective atmosphere: High-purity argon (oxygen content ≤100ppm);

[0112] Multivariate parameter design: Using energy density window as a constraint, a full factorial experimental design method is employed to systematically adjust parameters. , , Three variables:

[0113] 1. Laser power Set 5 levels (140W, 180W, 220W, 260W, 300W);

[0114] 2. Scanning speed Set 5 horizontal speeds (700mm / s, 800mm / s, 900mm / s, 1000mm / s, 1100mm / s).

[0115] 3. Scanning Spacing Set 5 levels (60μm, 70μm, 80μm, 90μm, 100μm)

[0116] Based on the above parameter combinations, multiple regions are divided within the XY plane of the printing model, and different combinations of process parameters are mapped to different regions to achieve simultaneous selection of multiple parameters within a single printing task. Parameter combinations whose calculated volumetric energy density exceeds the preset window range are only used as objects for parameter space construction and are not included in actual printing or subsequent analysis.

[0117] Parameter combination calculation:

[0118] A parameter combination space was constructed using a 5×5×5 configuration. Typical parameter examples are shown in Table 1, from which parameters with volumetric energy densities ranging from 50 to 200 J / mm³ were selected. 3 The combinations within the range are used as the actual objects for printing and analysis.

[0119] Table 1 Actual process parameters for different parameter combinations

[0120]

[0121] (2) Spatial misalignment control

[0122] Each parameter sub-region is mainly arranged along the XY plane, and a spatially staggered scanning strategy is adopted between adjacent sub-regions to reduce the overlap of heat input at the boundary.

[0123] In the first to fifth layers, all parameters except the laser power P remain unchanged, i.e., the single variable principle is followed.

[0124] A transition layer of 0.3–0.5 mm (approximately 8–12 layers) is set between adjacent parameter areas. The transition layer is printed using the parameters of the previous area and does not participate in the organization and performance analysis.

[0125] The height of each parameter region is greater than the height of the heat-affected zone of the IN738 alloy under this process condition (<1.5mm), which geometrically ensures that the steady-state microstructure of adjacent regions does not overlap spatially.

[0126] (3) Time window control

[0127] After printing a parameter area, a 10-20 second area-level cooling time (i.e., interval setting time or area switching time) is introduced.

[0128] Printing of the next parameter area only begins after the surface temperature of the area is confirmed to have dropped below the preset threshold (below the sensitive temperature zone where the γ′ phase is significantly redissolved) by the equipment temperature control and infrared monitoring.

[0129] This time window ensures that the microstructure of the previous region has been "locked in," preventing resolution or abnormal grain growth caused by subsequent printing.

[0130] (4) Regional boundary thermal guidance control

[0131] Within the two to three scanning tracks before and after the boundary of the parameter region, the following boundary scanning strategy is adopted: the laser power is reduced by 10 to 20% per track; the scanning direction is rotated 90° from the main scanning direction.

[0132] By guiding heat in the above manner, it is preferable to diffuse it towards the already solidified lower region rather than concentrate it towards the region with new parameters, thereby reducing heat accumulation in the boundary region.

[0133] III. Printing, Post-processing and Characterization

[0134] After printing, the entire sample was cooled to room temperature; the sample was then taken by wire cutting; and then subjected to uniform heat treatment: 1180°C×2h solution treatment (air cooling) + 1080°C×4h aging (air cooling) + 850°C×20h secondary aging (air cooling).

[0135] All tissue characterization and performance tests were conducted at the geometric center of each parameter region (≥1 mm from any boundary) to obtain the mapping relationship between the region-tissue-performance of the component, such as... Figures 6-8As shown, when the volumetric energy density is low, incomplete melting or porosity defects are more likely to appear in the sample; when the volumetric energy density is too high, crack sensitivity increases. Combining defect characteristics, relative density, and microstructure results, the suitable processing window for the IN738 alloy can be comprehensively determined.

[0136] Figure 5 This diagram illustrates the relationship between process parameters, microstructure, and properties, serving to explain the correspondence between differences in microstructure and properties under different process parameters. Figure 6 The image shows partial crack and pore features of the cut sample in Example 1, which demonstrates the feasibility of this method for defect comparison, thereby screening out process parameters without defects. Figure 7 To observe the microstructure of a partial cross-section under an optical microscope (OM) after printing with different parameters, the interface of samples prepared by multiple processes can be observed, so as to screen the process parameters that obtain a good interface and obtain the relationship between energy density, cracks and porosity. Figure 8 To investigate the relationship between density and energy density in cross-sections of certain regions after printing with different parameters, and to select process parameters for obtaining better microstructure, from... Figure 8 It can be seen that the energy density is between 100 and 150 J / mm². 3 Highly dense samples can be obtained through this process.

[0137] In this embodiment, the regional cooling time was determined by comparing the tissue stability and printing efficiency of the samples under different regional switching times. The comparison results are shown in Table 2.

[0138] Table 2 Evaluation of organizational stability and printing efficiency under different area switching times

[0139]

[0140] As shown in Table 2, when no region switching time is set, the tissue differences between adjacent regions and the center of the main body are significant, as evidenced by high levels of ΔKAM, ΔHV, and Δρcrack. When the region switching time increases to 5–20 s, these differences decrease significantly, indicating that the thermal effect superposition between adjacent regions is effectively weakened. When the region switching time is further increased to 50 s, the improvement in tissue stability is limited, but the total printing time per cycle increases significantly. Therefore, the preferred region switching time is 5–50 s, and more preferably 10–20 s, which achieves a good balance between tissue stability and printing efficiency.

[0141] IV. Implementation Results

[0142] Based on the correspondence between parameters, microstructure, and properties, multiple sets of process parameters can be simultaneously screened through a single printing operation. Results show that in this embodiment, when the volumetric energy density is low, the sample is prone to defects such as porosity; when the volumetric energy density is too high, crack susceptibility increases.

[0143] Based on the relative density, crack distribution, and microstructure characteristics, a suitable comprehensive processing window can be determined for the IN738 alloy. The optimal energy density range for densification is 80–130 J / mm². 3 After further considering crack sensitivity, the preferred process window is 100–130 J / mm. 3 .

[0144] Within the preferred process window, the representative preferred parameter set can be further selected as follows: laser power 220W, scanning speed 800mm / s, scanning track spacing 80μm, and layer thickness 30μm.

[0145] Example 2

[0146] This embodiment provides a method for screening different layer thickness parameters of IN738 alloy based on partitioned integrated design (powder and chemical composition are the same as in Example 1), such as Figure 9 As shown.

[0147] I. Parameter Design

[0148] Fixed parameters: Scanning interval: 80μm; Scanning strategy: long linear scan, interlayer rotation 67°, power and scanning speed are adjusted according to layer thickness.

[0149] Variable parameters: Layer thickness: 30μm, 60μm, 90μm, 120μm

[0150] II. Implementation of Time Window Control and Region Control

[0151] Within each layer, single-layer areas are scanned sequentially according to a preset order; the time interval between adjacent layers is 10–20 seconds.

[0152] This time window ensures that the printed area cools to a region insensitive to tissue evolution before being heated again.

[0153] III. Printing and Characterization

[0154] An integrated sample with four parameter states can be obtained in one printing. After the sample is cut, the center of each sub-region is subjected to: tissue observation, relative density test, crack density statistics, and microhardness test.

[0155] IV. Implementation Results

[0156] Based on the suitable energy input range obtained in Example 1, this example adjusts the laser power and scanning speed according to the layer thickness to ensure that samples with different layer thickness parameters are under comparable energy input conditions. Subsequently, the relative density, crack density, optical microstructure, EBSD microstructure characteristics, and microhardness of different layer thickness regions are compared and analyzed to establish the correspondence between layer thickness, microstructure, and properties, and to select a suitable range of layer thickness parameters accordingly.

[0157] The results show that there are significant differences in density, crack sensitivity, and grain morphology among different layer thicknesses. Combined with OM observations, it is evident that the 30–60 μm layer thickness region exhibits better forming quality with fewer porosity and crack defects, while the defect tendency increases with larger layer thicknesses. Further analysis with EBSD results shows that the 30–60 μm layer thickness region more readily yields a more continuous columnar grain structure, with fewer transverse grain boundaries and better grain orientation distribution and morphological continuity. Considering the relative density, crack density, microstructure, and EBSD results, 30–60 μm is determined to be the preferred layer thickness range for this embodiment.

[0158] in, Figure 10 The image shows a physical sample of the multilayer thick sample prepared in Example 2, demonstrating the feasibility of preparing regions of different layer thicknesses within the same sample. Figure 11 The image shows a comparison of the microstructure of OM (Oil and Metal) in cross-sections of different layer thicknesses. This can be used to compare the differences in porosity, cracks, and microstructure morphology under different layer thicknesses. A blue printed sample can be seen in the image. The blue arrow indicates the printing direction. The red arrow in the selected area is the result of regional characterization, indicating that the influence is small in the layered area and the process parameters above and below will not affect the already deposited microstructure. Figure 12 Comparison images of EBSD microstructures in cross-sections of regions with different layer thicknesses can be used to analyze grain morphology, grain orientation distribution, and transverse grain boundary characteristics under different layer thickness conditions. Figure 11 and Figure 12 The results show that the 30–60 μm layer thickness region is superior in terms of defect control and microstructure continuity, indicating that this layer thickness range is more conducive to obtaining a dense, low-crack, and better grain boundary topology microstructure, and provides a more favorable microstructure basis for subsequent high-temperature performance improvement.

[0159] Example 3

[0160] This embodiment provides a multi-parameter integrated printing method for IN738 alloy with a non-dense spacing structure between adjacent parameter regions. The powder material, printing equipment, protective atmosphere, and printing parameters of the main test area are the same as in Embodiment 1. The difference from Embodiment 1 is that an adjacent first region and a second region are set in the XY plane of the printed model. The first region is printed using a first set of process parameters, and the second region is printed using a second set of process parameters. A spacing structure is set between the first region and the second region, and the spacing structure is continuously arranged along the boundary direction between the two regions with a width of 0.4 mm.

[0161] The spacer structure includes a first section, a second section, and an intermediate spacer section. The first section is adjacent to the first region and is printed using the same set of process parameters as the first region. The second section is adjacent to the second region and is printed using the same set of process parameters as the second region. The intermediate spacer section employs a honeycomb-like non-dense structure with a fill density of 40%. This design ensures clear assignment of region parameters while reducing continuous solid heat conduction paths between adjacent test areas.

[0162] After printing, the sample was wire-cut, and its microstructure and properties were characterized at the center of the first region, the center of the second region, the region adjacent to the boundary, and the region adjacent to the spacer structure. The characterization included optical microstructure observation, EBSD analysis, relative density testing, crack density statistics, and microhardness testing.

[0163] The results show that, compared with the multi-region integrated sample without spacers, the 40% honeycomb spacer structure resulted in clearer boundary identification between adjacent regions, and the subsequent cutting and sampling positioning deviation decreased from 0.35 mm to 0.12 mm. Without spacers, the average KAM difference between the boundary-adjacent region and the central region was 0.42°, which decreased to 0.18° after the spacers were installed. Without spacers, the microhardness difference between the boundary-adjacent region and the central region was 67 HV, which decreased to 15 HV after the spacers were installed. Without spacers, the crack density in the boundary-adjacent region was 0.82 mm / mm², which decreased to 0.31 mm / mm² after the spacers were installed.

[0164] The above results show that non-dense spacer structures can reduce the continuous heat conduction and heat input superposition between adjacent parameter regions, making the microstructure and properties of the boundary adjacent regions closer to the corresponding main body region, thereby improving the reliability of the microstructure and property comparison between different parameter regions.

[0165] Example 4

[0166] This embodiment provides an optimization method for non-dense spacer structures with different fill densities. The powder material, printing equipment, protective atmosphere, main test area size, and main test area printing parameters used are the same as in Embodiment 3. The difference lies in that the intermediate spacer section is printed with a honeycomb non-dense structure with different fill densities: 5%, 10%, 20%, 40%, 60%, 80%, and 90%.

[0167] After printing, samples under different filling density conditions were subjected to physical observation, cut sample integrity observation, OM microstructure observation, EBSD analysis, crack density statistics, relative density test, and microhardness test. Evaluation indicators included: integrity of the spacer structure, regional boundary identification, cutting sampling stability, degree of microstructure disturbance in the boundary adjacent area, and thermal effect reduction effect between adjacent areas.

[0168] The results show that when the fill density is 5%, the continuity of the spacer structure is insufficient, some honeycomb units break or collapse, local damage easily occurs during sample preparation, and it is difficult to form stable and identifiable regional separation zones. When the fill density is increased to 10%, the spacer structure can be basically continuously formed and adjacent regions can be effectively distinguished. When the fill density is 20%–60%, the spacer structure has good forming integrity, regional identification, and thermal impact mitigation effect. The KAM difference, microhardness difference, and crack density difference between the boundary adjacent region and the main body center region are all at a low level. When the fill density increases to 80%, the spacer structure can still achieve regional separation, but due to the increased proportion of solid skeleton and the increase in continuous heat conduction paths, the thermal impact mitigation effect decreases. When the fill density is further increased to 90%, the structural difference between the spacer structure and the dense region of the main body decreases, the degree of tissue disturbance in the boundary adjacent region increases significantly, and the thermal isolation effect is insufficient.

[0169] Among them, the integrity of the forming is evaluated based on whether the spacer structure is continuously formed and whether local fracture occurs; the regional identification is evaluated based on whether the boundary of the adjacent main body test area is clear; the sample preparation stability is evaluated based on whether the spacer structure is locally damaged during the cutting, embedding and polishing process; the boundary thermal influence control is evaluated based on the difference in the structure and properties between the boundary adjacent area and the main body center area; the specific evaluation is shown in Table 3.

[0170] Table 3. Evaluation of the effects of different fill density spacing structures

[0171]

[0172] As shown in Table 3, the filling density of the non-dense spacer structure should not be too low or too high. When the filling density is below 10%, the structural continuity and mechanical integrity are insufficient; when the filling density is above 80%, the number of continuous heat conduction paths increases, which is not conducive to reducing the superposition of thermal effects between adjacent areas. Considering the overall integrity of the forming, regional identification, sample preparation stability, and thermal effect control, the filling density of the spacer structure is determined to be 10%–80%, preferably 20%–60%.

[0173] Comparative Example 1

[0174] This comparative example uses the traditional single-parameter, single-sample process screening method, such as... Figure 13 As shown. To compare and verify the technical advantages of this invention in high-throughput screening of additive manufacturing processes, the traditional "single parameter – single sample" experimental method was used to screen similar process parameters for IN738 nickel-based superalloy.

[0175] The same IN738 nickel-based superalloy powder and SLM equipment as in Example 1 were used, and the same 125 combinations of process parameters as in Example 1 were selected. In the conventional method, each set of process parameters requires printing a separate sample, with a sample size of 10mm × 10mm × 10mm, and each substrate can accommodate 10 samples.

[0176] To obtain statistically significant results, three samples were printed for each set of parameters. The overall experiment required the following: 36 independent printing jobs; 36 substrates used; 125 samples in total; 3 individual characterization analyses; and a total forming time of approximately 369 hours, excluding sample preparation, metallographic treatment, and subsequent analysis and testing time.

[0177] Experimental results show that the following technical defects exist when using the above traditional method for process parameter screening: (1) The experimental efficiency is significantly low: Each set of parameters needs to be printed and characterized separately, the experimental cycle is long, and it is difficult to support the systematic screening of a large-scale parameter space. (2) The batch effect leads to poor data consistency: Different parameter combinations are completed in different printing batches. During the printing process, the purity of the atmosphere, the state of the equipment and the temperature field fluctuations are inevitably affected, resulting in inconsistent initial thermal histories of the samples and obvious dispersion of the microstructure and performance results. (3) Insufficient reliability of crack-sensitive material comparison: For nickel-based superalloys such as IN738 that are highly sensitive to hot cracking, the crack formation behavior is extremely sensitive to thermal history. The differences between samples across batches make it difficult to make a real and reliable horizontal comparison between different parameter combinations, affecting the accuracy of process window determination. (4) High material and testing costs: The traditional method requires a large number of repeated printing and characterization, which significantly increases the costs of powder, protective gas, equipment time and labor. Specific comparisons are shown in Table 4.

[0178] Regarding experimental efficiency, a comparative example shows that preparing 125 sets of parameters × 3 replicates = 375 samples requires 36 independent printing jobs, accumulating approximately 375 hours of printing time. If sample preparation, pretreatment, and characterization are included, the total cycle is expected to exceed 9 weeks. In this invention's embodiment, 125 sets of parameters are simultaneously formed in a single printing job through integrated design, significantly reducing the total printing time compared to traditional batch printing methods. Sample preparation and pretreatment are completed concurrently. When completing the screening task with the same parameter space (125 sets), this invention improves the efficiency of the core printing process by an order of magnitude (>10 times) and avoids repeated equipment start-ups, shutdowns, and calibrations, greatly accelerating R&D iteration.

[0179] Regarding the data consistency comparison, the comparison example is as follows: 125 sets of parameters were distributed across 36 different printing batches. Between different batches, there were uncontrollable, slight differences in equipment status (such as laser power stability and optical system cleanliness), initial substrate temperature, atmosphere purity (oxygen content fluctuations), and ambient temperature.

[0180] Regarding the reliability of the comparison (especially for crack-sensitive materials), the comparative example is as follows: For the IN738 alloy, crack density is extremely sensitive to local thermal cycling. In conventional methods, even with identical process parameters, the crack density and distribution pattern of different batches of samples show significant fluctuations.

[0181] Regarding the comparison of cost and resource consumption, the comparative example: 36 substrates are consumed, 36 complete atmosphere replacements are performed (cumulative consumption of approximately 800-1000L of high-purity argon gas), the effective equipment time is 375+ hours, and subsequent independent cutting, mounting, polishing, etching, and characterization of 375 samples are required, resulting in extremely high labor and material costs. The embodiment of this invention: only 1 substrate is required, 1 atmosphere replacement is performed (argon gas consumption of approximately 10-15L), equipment time is <8 hours, sample post-processing can be performed in batches, and the overall cost is significantly lower than the traditional method.

[0182] Table 4. Comparison of printing efficiency between the present invention and the traditional single-parameter-single-sample method.

[0183]

[0184] A direct comparison of the specific data above demonstrates that while the traditional "single-parameter, single-sample" method can theoretically obtain parameter-performance data, its extremely low experimental efficiency, uncontrollable batch effect noise, poor reliability in evaluating sensitive materials, and high overall cost make it unsuitable for large-scale, systematic additive manufacturing process optimization research. In contrast, this invention, through integrated experimental design, achieves simultaneous multi-parameter and equal-condition comparisons in a single experiment, exhibiting significant advantages in efficiency, consistency, reliability, and economy, providing a reliable technical approach for the rapid development of additive manufacturing processes for high-performance alloys.

[0185] It is evident that the existing "single-parameter-single-sample" method can also obtain certain parameter-performance correlation information, but it is significantly inferior to the multi-parameter region integration screening method adopted in this invention in terms of experimental efficiency, resource consumption, and data comparability.

[0186] In contrast, this invention significantly reduces the interference of batch effects on results by simultaneously constructing multi-parameter forming regions in a single printing job. While significantly reducing experimental costs, it obtains parameter-microstructure-property mapping relationships with higher consistency and reliability, making it particularly suitable for process optimization research of high-temperature alloy materials such as IN738 that are highly sensitive to thermal history.

[0187] Comparative Example 2

[0188] This comparative example uses a traditional single-parameter sample preparation method (taking layer thickness parameter comparison as an example) to conduct a comparative study on the layer thickness parameters of IN738 nickel-based superalloy, serving as a comparative example.

[0189] By setting four different layer thicknesses (30μm, 60μm, 90μm, 120μm), and printing only a single layer thickness sample within the same batch (therefore, four printings are required depending on the layer thickness), this study aims to evaluate the inherent limitations of traditional experimental methods in terms of controlling variables, data reliability, and experimental efficiency. It provides a comparative basis for the necessity of novel, efficient experimental methods. Figure 14 As shown.

[0190] The material selected was IN738 nickel-based superalloy powder from the same batch as in Examples 1 and 2, and its chemical composition, particle size distribution and sphericity met the corresponding technical standards.

[0191] Equipment and process: Printing was performed on the same SLM equipment using fixed process parameters, with only layer thickness as the variable; the other parameters were set as follows: laser power: 280W; scanning speed: 900mm / s; scanning interval: 80μm; scanning strategy: 67° rotational scanning between layers; protective atmosphere: high-purity argon (oxygen content ≤100ppm); layer thickness settings: 30μm, 60μm, 90μm, 120μm (printed independently each time).

[0192] Sample preparation: Three replicate samples (size: 20mm × 20mm × 15mm) were prepared for each layer thickness, for a total of 12 samples. A separate slice file was created for each layer thickness parameter, and a complete printing job was performed. Before each printing, substrate clamping, equipment preheating (to 80℃), chamber vacuuming, and argon purging were performed (printing began after the oxygen content reached the required level). Printing tasks of different layer thicknesses were spaced 1–3 days apart to simulate the conditions of multiple batch experiments in actual R&D.

[0193] The preparation of 12 samples in this group required 4 independent printing operations, accumulating approximately 32 hours of machine time, consuming about 4 bottles of high-purity argon gas, and wasting about 2.5 kg of powder. If additional replicates or studies of greater layer thickness are needed, the cost and time will increase exponentially.

[0194] Traditional approach: Comparing four layer thicknesses (30μm, 60μm, 90μm, 120μm) requires four independent printing jobs. Each job involves: equipment preparation (preheating, atmosphere replacement) → printing → cooling → sampling → equipment cleaning. The total time can be as long as 5-7 days, consuming four substrates, a large amount of protective gas, and occupying continuous equipment time.

[0195] Since samples of different layer thicknesses need to be printed in different jobs, the thermal history and equipment conditions experienced by the samples are difficult to be completely consistent, making the microstructure and defect results obtained under different layer thickness conditions susceptible to batch-to-batch interference. In contrast, the embodiments of the present invention improve data consistency and screening efficiency by performing multi-parameter comparisons in the same reference sample or the same printing job.

[0196] Comparative Example 3

[0197] The difference between this comparative example and Example 3 is that no partition structure is set between the first region and the second region. The remaining powder materials, printing equipment, protective atmosphere, main test area size, printing parameters, sampling location and characterization method are the same as those in Example 3.

[0198] After printing, optical microstructure observation, EBSD analysis, crack density statistics, and microhardness testing were performed on the center of the first region, the center of the second region, and the adjacent area at the boundary between the two regions. The results showed that without the spacer structure, the boundaries between adjacent regions were not clear enough, and the adjacent area was more susceptible to the influence of heat input from the adjacent region. This manifested as a significant difference in the microstructure characteristics near the boundary compared to the corresponding main body area, and increased difficulty in cutting, sampling, and positioning. Compared to Example 3, the sample without the spacer structure was inferior in terms of region identification, boundary microstructure stability, and parameter assignment accuracy.

[0199] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for optimizing the additive manufacturing process of high-temperature alloys, characterized in that, Includes the following steps: Step 1): Divide the additive manufacturing high-temperature alloy printing model into multiple regions, and print each region using a preset set of process parameters; Step 2): The microstructure and mechanical properties of multiple regions after printing are characterized and tested to screen the process parameters for the additive manufacturing of the high-temperature alloy.

2. The method for optimizing the additive manufacturing process of high-temperature alloys according to claim 1, characterized in that, In step 1): when printing adjacent first and second regions consecutively, after the first region is printed, a set time interval is set to allow the temperature of the first region to drop below a preset cooling threshold before printing the second region. The additive manufacturing high-temperature alloy is a nickel-based high-temperature alloy; the preset cooling threshold is 50–200 °C below the γ′ phase solid solution temperature; The set time is 5 to 50 seconds.

3. The method for optimizing the additive manufacturing process of high-temperature alloys according to claim 1, characterized in that, In step 1): The adjacent areas adopt a spatially offset scanning strategy so that the scan lines of the adjacent areas are spatially offset by a set amount, which is 0.3 to 1.5 times the scanning track spacing.

4. The method for optimizing the additive manufacturing process of high-temperature alloys according to claim 1, characterized in that, When printing adjacent first and second regions, after the first region is printed, scanning is performed using one or more of the following methods: a. Perform a preheating scan on the side of the boundary between the first and second regions closer to the first region; wherein, the laser power of the preheating scan is 50-70% of the laser power used for printing the first region; b. In the second region, the laser power of the first 2 to 5 scan lines near the boundary between the first and second regions decreases sequentially; the decrease range is 10% to 40%. c. Adjust the scanning direction of the second region so that the heat conduction direction of the molten pool points towards the first region.

5. The method for optimizing the additive manufacturing process of high-temperature alloys according to claim 1, characterized in that, In step 1): when printing adjacent first and second regions consecutively, an interval structure is set between the first and second regions.

6. The method for optimizing the additive manufacturing process of high-temperature alloys according to claim 5, characterized in that, The filling configuration of the spacer structure is one or more of the following: lattice structure, honeycomb structure, and discontinuous grid. And / or, the filling density of the spacer structure is 10% to 80%.

7. The method for optimizing the additive manufacturing process of high-temperature alloys according to claim 5, characterized in that, The interval structure includes a first segment and a second segment; wherein the first segment is adjacent to the first region and is printed using the same set of process parameters as the first region; the second segment is adjacent to the second region and is printed using the same set of process parameters as the second region.

8. The method for optimizing the additive manufacturing process of high-temperature alloys according to claim 1, characterized in that, In step 1), the process parameter set includes one or more of the following: layer thickness, laser power, scanning speed, scanning track spacing, and scanning strategy. The layer thickness is 0.02–0.12 mm; the laser power is 140–400 W; the scanning speed is 700–1100 mm / s; the scanning track spacing is 0.06–0.1 mm; and the scanning strategy is long straight line scanning, checkerboard scanning, or spiral filling scanning.

9. The method for optimizing the additive manufacturing process of high-temperature alloys according to claim 8, characterized in that, At least one parameter is different in the process parameter groups corresponding to adjacent regions; And / or, the additive manufacturing high-temperature alloy is IN738 nickel-based high-temperature alloy; when the powder particle size of IN738 nickel-based high-temperature alloy is 15-53 μm, a layer thickness of 0.02-0.06 mm is used; when the powder particle size of IN738 nickel-based high-temperature alloy is 53-106 μm, a layer thickness of 0.06-0.12 mm is used.

10. The method for optimizing the additive manufacturing process of high-temperature alloys according to claim 1, characterized in that, In the step 1), parameters in the process parameter group are selected based on a volume energy density model; wherein, Ev=P / (v x h x t); wherein, Ev is volume energy density, unit is J / mm 3 ; P is laser power, unit is W; v is scanning speed, unit is mm / s; h is scanning track spacing, unit is mm; t is layer thickness, unit is mm; Among them, Ev is 10~500J / mm 3 .

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