A laser selective melting forming nickel-based alloy and a preparation method and application thereof

Abstract

The application discloses a laser selective melting forming nickel-based alloy and a preparation method and application thereof. The preparation method of the laser selective melting forming nickel-based alloy comprises the following steps: sequentially performing laser selective melting forming treatment, heat treatment and hot isostatic pressing treatment on alloy powder, and then the laser selective melting forming nickel-based alloy is obtained; in the laser selective melting forming, the laser power is 220-230 W, and the scanning speed is 1100-1120 mm / s; the heating temperature of the heat treatment is 1165-1185 DEG C, and the time for keeping the heating temperature is 2 h; the heating temperature of the hot isostatic pressing treatment is 1165-1185 DEG C, the time for keeping the heating temperature is 2 h, and the pressure is 158-162 MPa. The preparation method can stably improve the room temperature and high temperature mechanical properties of the laser selective melting forming nickel-based alloy, and can ensure the performance stability of multiple batches.

Description

Technical Field

[0001] This invention relates to the field of metal additive manufacturing, specifically to a laser selective melting forming method for nickel-based alloys and its preparation and application. Background Technology

[0002] Nickel-based superalloys possess excellent high-temperature strength, fatigue resistance, and creep resistance, making them irreplaceable key materials in the field of high-end power equipment. Hastelloy X alloy (domestic designation GH3536) is composed of γ matrix phase, carbide phases, and other components, exhibiting good oxidation resistance and corrosion resistance. It is suitable for manufacturing components for aero-engines and ground gas turbines operating below 900℃ and is one of the most widely used superalloys in the aerospace field.

[0003] With the development of advanced aero-engine and gas turbine technologies, the structural design of hot-end components is becoming increasingly complex. Traditional manufacturing processes, limited by their processing capabilities, cannot produce such intricate parts and must sacrifice some structural functionality, severely hindering the development of aero-engines and gas turbines. Selective Laser Melting (SLM) technology utilizes a high-energy laser beam to scan and melt pre-placed powder in a powder bed layer by layer, enabling the direct fabrication of near-net-shape parts from 3D digital models. It offers advantages such as low forming constraints, high precision, and low surface roughness, and has been gradually applied in the manufacturing of components with complex shapes or internal cavities. Domestic and international companies have begun large-scale application of SLM for Hastelloy X nickel-based superalloy products.

[0004] The laser selective melting forming process differs significantly from manufacturing processes such as forging and casting, mainly in the following aspects: (1) The molten pool in the laser selective melting forming process is small (100-300 μm), with a large temperature gradient and extremely fast solidification rate; (2) The temperature gradient of the molten pool is roughly along the deposition direction. When the laser beam scans the powder layer, it remelts the top of the solidified columnar crystals of the previous layer. The unmelted part of the columnar crystals becomes the nucleus for the directional solidification of the layer, causing the original columnar grains of the previous layer to continue to grow epitaxially along the deposition direction; (3) During the forming process, the layer-by-layer accumulation leads to rapid and repeated heating of the molten pool, resulting in large residual stress. These characteristics lead to significant differences between the SLM forming structure and traditional casting and forging. However, the properties of Hastelloy X alloy mainly depend on the microstructure of the alloy, which is closely related to the alloy composition, manufacturing method, and heat treatment parameters. The unique process of selective laser melting (SLM) means that the compositional requirements and heat treatment regimes suitable for cast and forged Hastelloy X alloys may not be suitable for Hastelloy X alloys manufactured by SLM. Compared with the performance of forged Hastelloy X, SLM-formed Hastelloy X alloys have relatively lower creep. To ensure that SLM-formed Hastelloy X alloys possess good room temperature and high temperature mechanical properties, it is necessary to establish alloy composition, forming process, and heat treatment regimes that are compatible with the SLM process.

[0005] Chinese Patent CN 106513660A provides a Hastelloy X high-temperature alloy powder for powder bed additive manufacturing, optimizing the alloy composition and controlling the C / B content ratio to suppress crack initiation during the additive manufacturing process. Chinese Patent CN 113305285A invents a Hastelloy X high-temperature powder for additive manufacturing to improve formability and eliminate microcracks and macrocracks generated during the additive manufacturing process. Chinese Patent CN 111390180A provides a method to improve the creep rupture performance of GH3536 alloy manufactured by selective laser melting (SLM) technology, optimizing the alloy heat treatment process to achieve high-temperature creep rupture performance meeting forging standards. Chinese Patent CN 113042755A provides a heat treatment method for GH3536 high-temperature alloy used in additive manufacturing, improving the performance of GH3536 high-temperature alloy for additive manufacturing by controlling the process conditions during heat treatment, bringing its performance close to that of forgings. Chinese patent CN 113618068A discloses a method for laser additive manufacturing of high-performance GH3536 nickel-based superalloy without hot cracking. It adds an appropriate amount of TiB2 particles to suppress cracking during the additive manufacturing process of GH3536 alloy, thus expanding the additive manufacturing process parameter window for this alloy. It is worth noting that Hastelloy X alloy is an important material used in manufacturing components for aero-engines and ground-based gas turbines operating below 900°C. Its mechanical properties at room temperature and below 900°C are particularly critical, especially its creep life and tensile strength below 900°C, which are crucial for the durability of the components. As mentioned earlier, the performance of Hastelloy X alloy is closely related to its composition, manufacturing method, and heat treatment parameters. The aforementioned patents all propose methods to improve the mechanical properties of laser selective melting Hastelloy X alloy from the perspective of heat treatment or powder modification, but they cannot guarantee that multiple batches of alloy can maintain stable performance. A search of relevant domestic and international patents reveals that methods for stably improving the performance of laser selective melting Hastelloy X alloy below 900°C are rarely mentioned.

[0006] Therefore, there is an urgent need to provide a laser selective melting forming nickel-based alloy whose mechanical properties can be stably improved at both room temperature and high temperature, and whose performance stability across multiple batches can continuously and stably meet the requirements of aerospace products. Summary of the Invention

[0007] The technical problem to be solved by this invention is to overcome the shortcomings of existing technologies that are difficult to stably improve the room temperature and high temperature mechanical properties of laser selective melting formed nickel-based alloys, and that the performance stability across multiple batches is poor. This invention provides a laser selective melting formed nickel-based alloy, its preparation method, and its applications. The preparation method of this invention can stably improve the room temperature and high temperature mechanical properties of laser selective melting formed nickel-based alloys and can ensure the performance stability across multiple batches. Simultaneously, the obtained laser selective melting formed nickel-based alloy exhibits good high-temperature durability, uniform microstructure, and high density.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] One of the technical solutions provided by this invention is: a method for preparing a nickel-based alloy by selective laser melting, comprising the following steps: sequentially subjecting the alloy powder to selective laser melting, heat treatment, and hot isostatic pressing.

[0010] The alloy powder contains 9.0%-10.0% Mo, 0.8%-1.0% W, <0.3% Si, and 0.01%-0.015% P; the percentages are the mass percentages of each element in the alloy powder.

[0011] In the laser selective melting and forming process, the laser power is 220-230W and the scanning speed is 1100-1120mm / s;

[0012] The heat treatment is carried out at a temperature of 1165-1185℃ for 2 hours; after maintaining the heat treatment temperature for 2 hours, cooling is performed.

[0013] The heating temperature for the hot isostatic pressing treatment is 1165-1185℃, and the heating time is 2 hours; the pressure for maintaining the heating temperature is 158-162 MPa; after maintaining the heating temperature for the hot isostatic pressing treatment for 2 hours, cooling is performed.

[0014] In this invention, the alloy powder generally refers to the raw material of Hastelloy X high-temperature alloy.

[0015] The C content in the alloy powder can be 0.05-0.12%; preferably 0.067-0.11%.

[0016] The Cr content can be 20.5%-23.0%, preferably 21.43%-22.03%.

[0017] The Co content can be 1.0%-2.5%, preferably 1.52%-1.79%.

[0018] The preferred Mo content is 9.0%-9.4%.

[0019] The preferred content of W is 0.85%-0.88%.

[0020] The Fe content can be 17.0%-20.0%, preferably 18.34%-18.5%.

[0021] The content of B can be <0.010%, preferably 0.002%-0.003%.

[0022] The Mn content can be <0.5%, preferably 0.005%-0.006%.

[0023] The Si content is preferably 0.038%-0.063%.

[0024] The content of sulfur (S) can be <0.015%, preferably 0.0015%.

[0025] The content of phosphorus (P) is preferably 0.012%-0.015%.

[0026] The Cu content can be <0.015%, preferably 0.006%-0.008%.

[0027] The Al content can be <0.5%, preferably 0.059%-0.086%.

[0028] The Ti content can be <0.15%, preferably 0.007%-0.014%.

[0029] The content of O can be <0.02%, preferably 0.008%-0.009%.

[0030] The nitrogen content can be <0.015%, preferably 0.003%-0.007%.

[0031] The Ni content is generally in the balance.

[0032] The particle size distribution range of the alloy powder can be conventional in the art, preferably 15-45 μm.

[0033] In this invention, the laser selective melting forming can generally be performed in an argon atmosphere. The purity of the argon gas in the argon atmosphere can be above 99.99 wt%.

[0034] In the laser selective melting forming process, the argon gas flow rate in the forming chamber can be 0.5–0.7 m / s; this is used to control the dust generated during the laser selective melting forming process. The oxygen content in the forming chamber can be below 0.1%.

[0035] In the laser selective melting forming process, the spot diameter can be conventional in the field, preferably 0.1 mm.

[0036] In the laser selective melting forming process, the scanning interval can be conventional in the field, preferably 0.09-0.1 mm.

[0037] In the laser selective melting forming process, the powder layer thickness can be conventional in the art, preferably 0.04 mm.

[0038] In this invention, the process parameters of laser selective melting forming can improve the sintering rate of the alloy, and at the same time, it is beneficial to improve the forming quality and efficiency.

[0039] In this invention, the heat treatment can generally be carried out under vacuum conditions or a protective atmosphere.

[0040] In the heat treatment, the preferred heating temperature is 1175°C.

[0041] In the heat treatment, the cooling can be conventional in the art. The cooling rate can be (5-10) °C / min; preferably 5 °C / min. The cooling temperature can be below 425 °C.

[0042] In this invention, the hot isostatic pressing process can generally be carried out under vacuum conditions and a protective atmosphere. Preferably, the vacuum level is no higher than 100 Pa. The protective atmosphere is preferably an argon atmosphere.

[0043] In the hot isostatic pressing process, the rate of heating to the heating temperature is preferably 5°C / min.

[0044] The preferred heating temperature for the hot isostatic pressing process is 1175°C.

[0045] In the hot isostatic pressing process, the pressure used to maintain the heating temperature is preferably 160 MPa.

[0046] In the hot isostatic pressing process, the cooling can be conventional in the art. The cooling rate can be (5-10) °C / min; preferably 5 °C / min. The cooling temperature can be below 425 °C.

[0047] The second technical solution provided by the present invention is: a laser selective melting forming nickel-based alloy, which is prepared by the above-mentioned laser selective melting forming nickel-based alloy preparation method.

[0048] The third technical solution provided by the present invention is: the application of the laser selective melting forming nickel-based alloy in hot-end components of aero-engines and ground gas turbines.

[0049] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0050] The reagents and raw materials used in this invention are all commercially available.

[0051] The positive and progressive effects of this invention are as follows:

[0052] By using the alloy powder of this invention and optimizing the process parameters in the laser selective melting forming, heat treatment and hot isostatic pressing steps, residual stress and defects in laser selective melting forming nickel-based alloys can be eliminated, crack sources can be eliminated, and the microstructure can be made uniform and dense. This can stably improve the room temperature and high temperature mechanical properties and durability of laser selective melting forming nickel-based alloys, and ensure the performance stability of multiple batches, stably meeting the needs of the aerospace field.

[0053] The laser selective melting forming method for preparing nickel-based alloys in this invention is simple and can achieve short-cycle manufacturing of complex alloy structural parts. Attached Figure Description

[0054] Figure 1-a This is a comparison chart of the room temperature and high temperature mechanical properties of the Hastelloy X alloy in Comparative Example 1 and Example 2.

[0055] Figure 1-b This is a comparison chart of the creep life of Hastelloy X alloy in Comparative Example 1 and Example 2.

[0056] Figure 2-a This is a comparison chart of the room temperature and high temperature mechanical properties of the Hastelloy X alloy in Comparative Example 2 and Example 2.

[0057] Figure 2-b This is a comparison chart of the creep life of Hastelloy X alloy in Comparative Example 2 and Example 2.

[0058] Figure 3 This is a comparison chart of the creep life of the Hastelloy X alloy in Comparative Example 3 and Example 2.

[0059] Figure 4 The image shows the morphology of defects in the deposited microstructure of the Hastelloy X alloy obtained by SLM in Example 2.

[0060] Figure 5 The image shows the microstructure of the Hastelloy X alloy obtained by SLM in Example 2 after heat treatment and hot isostatic pressing.

[0061] Figure 6 The image shows the SEM image of the grain morphology of the Hastelloy X alloy obtained by SLM in Example 2 after heat treatment and hot isostatic pressing.

[0062] Figure 7The image shows the SEM images of the intragranular and grain boundary precipitates of the Hastelloy X alloy obtained by SLM in Example 2 after heat treatment and hot isostatic pressing. Detailed Implementation

[0063] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0064] Explanation of technical terms:

[0065] Additive manufacturing technology, also known as 3D printing technology, mainly uses powder, granules or metal wires as raw materials. Through pre-layer processing of CAD models, high-energy beam melting and deposition growth is adopted ("additive manufacturing") to directly complete the "near-net-shape" of high-performance components from CAD models in one step.

[0066] Selective laser melting: an additive manufacturing technology that uses laser melting of pre-placed metal powder to form parts.

[0067] Stress Rupture: The duration and plasticity of a test specimen from intact to fracture under specified temperature and constant test force.

[0068] The preparation method of laser selective melting forming nickel-based alloys in the following examples and comparative examples includes the following steps:

[0069] (1) Preparation of nickel-based alloy powder formed by selective laser melting;

[0070] (2) Import the model of the part to be formed into the laser selective melting forming equipment, and perform substrate leveling and pre-powdering;

[0071] (3) Introduce a protective atmosphere and set the melting and forming parameters; after melting and forming is completed, clean the part;

[0072] (4) After heat treatment, the part is separated from the substrate;

[0073] (5) The heat-treated parts are subjected to hot isostatic pressing.

[0074] Example 1

[0075] (1) Prepare the first batch of Hastelloy X high-temperature alloy powder

[0076] The particle size distribution of Hastelloy X high-temperature alloy powder ranges from 15μm to 45μm;

[0077] The powder composition (by weight percentage) is as follows:

[0078] C: 0.067%, Cr: 21.43%, Co: 1.79%, Mo: 9.4%, W: 0.85%, Fe: 18.34%, B: 0.002%, Mn: 0.006%, Si: 0.063%, S: 0.0015%, P: 0.012%, Cu: 0.008%, Al: 0.059%, Ti: 0.014%, O: 0.008%, N: 0.007%, Ni: balance.

[0079] (2) The model of the part to be formed is imported into the laser selective melting forming equipment, and the substrate is leveled and pre-powdered, as follows:

[0080] ① Based on the required features of the formed part, a three-dimensional model is created on the computer and saved as an STL file. This model is then imported into the construction software of the laser selective melting forming equipment for layer processing.

[0081] ② The substrate of the forming chamber is made of stainless steel. The substrate is leveled and then the nickel-based high-temperature alloy powder obtained in step (1) is loaded into the powder supply cylinder of the powder bed selective laser melting forming equipment. The powder is evenly spread on the forming substrate using a scraper and the equipment door is closed.

[0082] (3) Introduce a protective atmosphere and set the melting and forming parameters:

[0083] High-purity argon gas (99.99 wt%) is introduced for protection, and the oxygen content in the cavity is controlled to be ≤0.1%. The argon flow rate in the forming chamber is set to 0.5 m / s to ensure effective control of fumes during the forming process. The laser power is set to 230 W, the spot diameter to 0.1 mm, the scanning speed to 1200 mm / s, the scanning interval to 0.09 mm, and the powder layer thickness to 0.04 mm.

[0084] (4) After melting and forming, the part is cleaned: the residual powder of the formed sample is cleaned.

[0085] (5) Heat treatment of Hastelloy X alloy parts:

[0086] Heat to 1175℃±10℃ in a vacuum or protective atmosphere, hold for 2 hours, then cool to below 425℃ at a rate of 5℃ / min, and then air cool to room temperature.

[0087] (6) Separation of the part from the substrate: The part is separated from the substrate by wire cutting process.

[0088] (7) Hot isostatic pressing treatment of Hastelloy X alloy parts:

[0089] With a vacuum level not exceeding 100 Pa in the working chamber, argon is filled as a protective gas. The heating rate is 5℃ / min, and the temperature is maintained at 1175±10℃ and 160MPa±2MPa for 2 hours. Then, the temperature is cooled to below 425℃ at a rate of 5℃ / min.

[0090] In Example 1, the density of the Hastelloy X high-temperature alloy formed part obtained by SLM was 99.85%, and the density after heat treatment / hot isostatic pressing was 99.96%. The room temperature and high-temperature mechanical properties are shown in Table 1, all of which meet the Hastelloy X forging standard requirements. The tensile strength was tested using ASTM E 8 / E8M, the yield strength using ASTM E 21, and the elongation using ASTM E 139.

[0091] Table 1. Room temperature and high temperature mechanical properties of Hastelloy X high-temperature alloys obtained by SLM in Example 1

[0092]

[0093] Example 2

[0094] (1) Prepare the second batch of Hastelloy X high-temperature alloy powder

[0095] The particle size distribution of Hastelloy X high-temperature alloy powder ranges from 15μm to 45μm;

[0096] The powder composition (by weight percentage) is as follows:

[0097] C: 0.11%, Cr: 22.03%, Co: 1.52%, Mo: 9.0%, W: 0.88%, Fe: 18.5%, B: 0.003%, Mn: 0.005%, Si: 0.038%, S: 0.0015%, P: 0.015%, Cu: 0.006%, Al: 0.086%, Ti: 0.007%, O: 0.009%, N: 0.003%, Ni: balance.

[0098] (2) Same as Example 1.

[0099] (3) Introduce a protective atmosphere and set the melting and forming parameters:

[0100] High-purity argon gas (99.99 wt%) was introduced for protection, and the oxygen content in the cavity was controlled to be ≤0.1%. The argon gas flow rate in the forming chamber was set to 0.7 m / s to ensure effective control of fumes during the forming process. The laser power was set to 220 W, the spot diameter to 0.1 mm, the scanning speed to 1100 mm / s, the scanning interval to 0.1 mm, and the powder layer thickness to 0.04 mm.

[0101] (4) Same as Example 1.

[0102] (5) Heat treatment of Hastelloy X alloy parts:

[0103] Heat to 1175℃±10℃ in a vacuum or protective atmosphere, hold for 2 hours, then cool to below 425℃ at a rate of 5℃ / min, and then air cool to room temperature.

[0104] (6) Consistent with Example 1.

[0105] (7) Hot isostatic pressing treatment of Hastelloy X alloy parts:

[0106] With a vacuum level not exceeding 100 Pa in the working chamber, argon is filled as a protective gas. The heating rate is 5℃ / min, and the temperature is maintained at 1175±10℃ and 160MPa±2MPa for 2 hours. Then, the temperature is cooled to below 425℃ at a rate of 5℃ / min.

[0107] In Example 2, the density of the Hastelloy X high-temperature alloy formed part obtained by SLM was 99.67%, and the density after heat treatment / hot isostatic pressing was 99.92%. The room temperature and high-temperature mechanical properties are shown in Table 2, all of which meet the Hastelloy X forging standard requirements. The tensile strength was tested using ASTM E 8 / E8M, the yield strength using ASTM E 21, and the elongation using ASTM E 139.

[0108] Table 2. Room temperature and high temperature mechanical properties of Hastelloy X high-temperature alloys obtained by SLM in Example 2

[0109]

[0110]

[0111] The morphology of the deposited microstructure defects in the Hastelloy X alloy obtained by SLM in Example 2 is shown below. Figure 4 As shown, only a small number of pore defects exist in its structure.

[0112] The microstructure of the Hastelloy X alloy obtained by SLM in Example 2 after heat treatment and hot isostatic pressing is shown in the following figure. Figure 5 As shown, the porosity defects in its tissue have disappeared.

[0113] The grain morphology of the Hastelloy X alloy obtained by SLM in Example 2 after heat treatment and hot isostatic pressing is shown in the figure below. Figure 6 As shown, recrystallization has occurred in its structure, resulting in isometric grains and fine, dispersed grains.

[0114] The morphology of intragranular and grain boundary precipitates in the Hastelloy X alloy obtained by SLM in Example 2 after heat treatment and hot isostatic pressing is shown in the following figures. Figure 7 As shown, the precipitates are distributed in a chain-like pattern at the grain boundaries, and a small amount of blocky precipitates exist within the grains, which helps to reduce crack initiation under stress.

[0115] Example 3

[0116] (1) Prepare the third batch of Hastelloy X high-temperature alloy powder

[0117] The particle size distribution of Hastelloy X high-temperature alloy powder ranges from 15μm to 45μm;

[0118] The powder composition (by weight percentage) is as follows:

[0119] C: 0.09%, Cr: 22.03%, Co: 1.52%, Mo: 9.0%, W: 0.82%, Fe: 18.5%, B: 0.002%, Mn: 0.005%, Si: 0.038%, S: 0.0015%, P: 0.015%, Cu: 0.006%, Al: 0.086%, Ti: 0.007%, O: 0.009%, N: 0.003%, Ni: balance.

[0120] (2) Same as Example 1.

[0121] (3) Same as Example 2.

[0122] (4) Same as Example 1.

[0123] (5) Same as Example 1.

[0124] (6) Consistent with Example 1.

[0125] (7) Same as Example 1.

[0126] In Example 3, the density of the Hastelloy X high-temperature alloy formed part obtained by SLM was 99.46%, and the density after heat treatment / hot isostatic pressing was 99.92%. The room temperature and high-temperature mechanical properties are shown in Table 3, all of which meet the Hastelloy X forging standard requirements. The tensile strength was tested using ASTM E 8 / E8M, the yield strength using ASTM E 21, and the elongation using ASTM E 139.

[0127] Table 3. Room temperature and high temperature mechanical properties of Hastelloy X high-temperature alloys obtained by SLM in Example 3

[0128]

[0129]

[0130] Based on the combined effect data from Examples 1, 2, and 3, the fluctuations in room temperature and high temperature mechanical properties of the three batches of Hastelloy X high-temperature alloys are shown in Table 4.

[0131] Table 4. Room temperature and high temperature mechanical property dispersion coefficients of three batches of Hastelloy X superalloys from Examples 1-3.

[0132] Test Project <![CDATA[Average value a v / MPa]]> Standard deviation s / MPa <![CDATA[Coefficient of dispersion Cv = s / a v > room temperature tensile strength 740.11 8.02 1.08％ room temperature yield strength 363.56 14.18 3.90％ 815℃ tensile strength 328.67 4.90 1.49％ Yield strength at 815℃ 219 10.32 4.71％

[0133] As shown in Table 4, the mechanical properties of the three batches of Hastelloy X high-temperature alloy in Examples 1 to 3 fluctuated little, which can effectively ensure the performance stability of multiple batches.

[0134] Comparative Example 1

[0135] (1) The fourth batch of Hastelloy X high-temperature alloy powder was prepared, wherein W and P are not within the scope of protection claimed in this invention.

[0136] The particle size distribution of Hastelloy X high-temperature alloy powder ranges from 15μm to 45μm;

[0137] The powder composition (by weight percentage) is as follows:

[0138] C: 0.065%, Cr: 21.5%, Co: 1.52%, Mo: 9.14%, W: 0.53%, Fe: 19.27%, B: 0.002%, Mn: 0.003%, Si: 0.07%, S: 0.002%, P: 0.006%, Cu: 0.009%, Al: 0.05%, Ti: 0.003%, O: 0.018%, N: 0.008%, Ni: balance.

[0139] (2) Same as Example 2.

[0140] (3) Introduce a protective atmosphere and set the melting and forming parameters:

[0141] High-purity argon gas (99.99wt%) was introduced for protection, and the oxygen content in the cavity was controlled to be ≤0.1%. The argon gas flow rate in the forming chamber was set to 0.7m / s to ensure effective control of fumes during the forming process. The laser power was set to 240W, the spot diameter to 0.1mm, the scanning speed to 1400mm / s, the scanning interval to 0.1mm, and the powder layer thickness to 0.04mm.

[0142] (4) Same as Example 2.

[0143] (5) Same as Example 2.

[0144] (6) Same as Example 2.

[0145] (7) Same as Example 2.

[0146] In Comparative Example 1, the density of the Hastelloy X high-temperature alloy formed part obtained by SLM in the deposited state was 99.04%, and the density after heat treatment / hot isostatic pressing was 99.98%.

[0147] The results of the comparison of room temperature and high temperature mechanical properties between Comparative Example 1 and Example 2 are as follows: Figure 1-a As shown, the results of the long-term lifetime comparison are as follows: Figure 1-b As shown. By Figure 1-a and Figure 1-b It is evident that the mechanical properties and service life of Comparative Example 1 are significantly lower than those of Example 2.

[0148] Comparative Example 2

[0149] (1) The fifth batch of Hastelloy X high-temperature alloy powder was prepared, wherein Mo, Si and P are not within the scope of protection claimed in this invention.

[0150] The particle size distribution of Hastelloy X high-temperature alloy powder ranges from 15μm to 45μm;

[0151] The powder composition (by mass percentage) is as follows: C: 0.053%, Cr: 21.49%, Co: 1.56%, Mo: 8.8%, W: 0.59%, Fe: 18.79%, B: 0.001%, Mn: 0.011%, Si: 0.35%, S: 0.002%, P: 0.001%, Cu: 0.002%, Al: 0.004%, Ti: 0.003%, O: 0.007%, N: 0.004%, Ni: balance.

[0152] (2) Same as Example 2.

[0153] (3) Introduce a protective atmosphere and set the melting and forming parameters.

[0154] High-purity argon gas (99.99 wt%) was introduced for protection, and the oxygen content in the cavity was controlled to be ≤0.1%. The argon gas flow rate in the forming chamber was set to 0.7 m / s to ensure effective control of fumes during the forming process. The laser power was set to 220 W, the spot diameter to 0.1 mm, the scanning speed to 1100 mm / s, the scanning interval to 0.1 mm, and the powder layer thickness to 0.04 mm.

[0155] (4) Same as Example 2.

[0156] (5) Same as Example 2.

[0157] (6) Same as Example 2.

[0158] (7) Same as Example 2.

[0159] In Comparative Example 2, the density of the Hastelloy X high-temperature alloy formed part obtained by SLM in the deposited state was 99.38%, and the density after heat treatment / hot isostatic pressing was 99.99%.

[0160] The results of the comparison of room temperature and high temperature mechanical properties between Comparative Example 2 and Example 2 are as follows: Figure 2-a As shown, the results of the long-term lifetime comparison are as follows: Figure 2-b As shown. By Figure 2-a and Figure 2-b It is evident that the mechanical properties and service life of Comparative Example 2 are significantly lower than those of Example 2.

[0161] Comparative Example 3

[0162] (1) Prepare the third batch (same as Example 3) of Hastelloy X high-temperature alloy powder.

[0163] The particle size distribution of Hastelloy X high-temperature alloy powder ranges from 15μm to 45μm;

[0164] The powder composition (by weight percentage) is as follows:

[0165] C: 0.09%, Cr: 22.03%, Co: 1.52%, Mo: 9.0%, W: 0.82%, Fe: 18.5%, B: 0.002%, Mn: 0.005%, Si: 0.038%, S: 0.0015%, P: 0.015%, Cu: 0.006%, Al: 0.086%, Ti: 0.007%, O: 0.009%, N: 0.003%, Ni: balance.

[0166] (2) The model of the part to be formed is imported into the laser selective melting forming equipment, and the substrate is leveled and pre-powdered, which is the same as in Example 2.

[0167] (3) Introduce a protective atmosphere and set the melting and forming parameters, which are consistent with those in Example 2.

[0168] (4) After melting and forming, the part is cleaned, which is the same as in Example 2.

[0169] (5) The part is separated from the substrate, as in Example 2.

[0170] (6) The parts are subjected to hot isostatic pressing.

[0171] Consistent with step (7) of Example 2.

[0172] (7) Heat treatment of the parts

[0173] Heat to 1125℃±10℃ in a vacuum or protective atmosphere, hold for 2 hours, and then air cool to room temperature.

[0174] In Comparative Example 3, the density of the Hastelloy X high-temperature alloy formed part obtained by SLM in the deposited state was 99.21%, and the density after heat treatment / hot isostatic pressing was 99.99%.

[0175] The room temperature and high temperature mechanical properties and creep life of Comparative Example 3 are significantly lower than those of Example 2. The creep life comparison results between Comparative Example 3 and Example 2 are as follows: Figure 3 As shown.

[0176] Based on the combined data from Comparative Examples 1, 2, and 3, the fluctuations in room temperature and high temperature mechanical properties of the three batches of Hastelloy X high-temperature alloys are shown in Table 5.

[0177] Table 5. Dispersion coefficients of room temperature and high temperature mechanical properties of three batches of Hastelloy X high-temperature alloys (Comparative Examples 1-3)

[0178]

[0179]

[0180] As can be seen from Table 5, the mechanical properties of the three batches of Hastelloy X high-temperature alloys in Comparative Examples 1 to 3 fluctuated significantly, making it difficult to guarantee the performance stability of multiple batches, and the effect was not as good as that of Examples 1 to 3.

[0181] As can be seen from the above embodiments and comparative examples, there is a synergistic effect between the various steps and conditions and parameters in this invention. When a certain parameter or a certain process step is not within the scope of protection claimed in this invention, the performance of the resulting product is inferior to that of the embodiments of this invention.

[0182] This invention comprehensively considers the key factors affecting the microstructure of alloys—powder composition, laser selective melting forming process, and heat treatment / hot isostatic pressing process—and proposes control requirements for each step. This achieves control over the morphology and distribution of intragranular precipitates, control over the morphology and content of grain boundary precipitates, and improvement of grain boundary bonding; elimination of defects such as porosity; reduction of stress concentration and crack propagation during deformation; and can stably improve the room temperature and high temperature mechanical properties and durability of laser selective melting formed nickel-based alloys, while ensuring performance stability across multiple batches, consistently meeting the requirements of the aerospace field.

Claims

1. A method for preparing nickel-based alloys by laser selective melting, characterized in that, It includes the following steps: sequentially performing laser selective melting forming, heat treatment, and hot isostatic pressing on the alloy powder; The alloy powder contains 0.067%-0.11% carbon. The Cr content is 21.43%-22.03%; The Co content is 1.52%-1.79%; The Mo content is 9.0%-9.4%; The content of W is 0.85%-0.88%; The Fe content is 18.34%-18.5%; The content of B is 0.002%-0.003%; The Mn content is 0.005%-0.006%; The Si content is 0.038%-0.063%; The content of sulfur (S) is 0.0015%. The content of phosphorus (P) is 0.012%-0.015%; The Cu content is 0.006%-0.008%; The Al content is 0.059%-0.086%; The Ti content is 0.007%-0.014%; The content of O is 0.008%-0.009%; The nitrogen content is 0.003%-0.007%; The Ni content is in the balance; The percentage represents the mass percentage of each element in the alloy powder; In the laser selective melting and forming process, the laser power is 220-230W and the scanning speed is 1100-1120mm / s; The heat treatment is carried out at a temperature of 1165-1185℃ for 2 hours; after maintaining the heat treatment temperature for 2 hours, cooling is performed. The heating temperature for the hot isostatic pressing treatment is 1165-1185℃, and the heating time is 2 hours; the pressure for maintaining the heating temperature is 158-162 MPa; after maintaining the heating temperature for the hot isostatic pressing treatment for 2 hours, cooling is performed.

2. The method for preparing nickel-based alloys by laser selective melting as described in claim 1, characterized in that, The particle size distribution of the alloy powder ranges from 15 to 45 μm.

3. The method for preparing nickel-based alloys by laser selective melting as described in claim 1, characterized in that, The laser selective melting and forming is performed in an argon atmosphere; the purity of the argon gas in the argon atmosphere is above 99.99 wt%. And / or, in the laser selective melting forming process, the argon gas flow rate in the forming chamber is 0.5 to 0.7 m / s; And / or, in the laser selective melting forming process, the oxygen content in the forming chamber is below 0.1%.

4. The method for preparing nickel-based alloys by laser selective melting as described in claim 1, characterized in that, In the laser selective melting forming process, the laser spot diameter is 0.1 mm; And / or, in the laser selective melting forming process, the scanning interval is 0.09-0.1 mm; And / or, in the laser selective melting forming process, the powder layer thickness is 0.04 mm.

5. The method for preparing nickel-based alloys by laser selective melting as described in claim 1, characterized in that, The heat treatment is carried out under vacuum conditions or a protective atmosphere; And / or, in the heat treatment, the heating temperature is 1175°C; And / or, in the heat treatment, the cooling rate is 5-10°C / min; the cooling temperature is below 425°C.

6. The method for preparing nickel-based alloys by laser selective melting as described in claim 1, characterized in that, The hot isostatic pressing process is carried out under vacuum conditions and a protective atmosphere; The vacuum level of the vacuum condition is no higher than 100 Pa; the protective atmosphere is an argon atmosphere.

7. The method for preparing nickel-based alloys by laser selective melting as described in claim 1, characterized in that, In the hot isostatic pressing process, the rate of heating to the heating temperature is 5°C / min; And / or, the heating temperature of the hot isostatic pressing treatment is 1175°C; And / or, in the hot isostatic pressing process, the pressure maintaining the heating temperature is 160 MPa; And / or, in the hot isostatic pressing process, the cooling rate is 5-10°C / min; the cooling temperature is below 425°C.

8. A laser selective melting forming method for nickel-based alloys, characterized in that, It is prepared by the laser selective melting forming method for nickel-based alloys as described in any one of claims 1 to 7.

9. The application of a laser selective melting forming nickel-based alloy as described in claim 8 in hot-end components of aero-engines and ground gas turbines.

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