Laser additive manufacturing aging steel, heat treatment preparation method and application

Abstract

The invention discloses laser additive manufacturing aging steel and a heat treatment preparation method and application, and belongs to the technical field of metal material machining. The preparation method of the laser additive manufacturing aging steel comprises the following steps: weighing the following raw material powder in percentage by mass: 40%-50% of Fe, 10%-18% of Cr, 22%-32% of Ni, 2.0%-2.5% of Al and 1.0%-1.5% of Ti; and the weighed raw material powder is uniformly mixed to obtain alloy powder, and the alloy powder is processed by adopting a selective laser melting method in an inert gas protection environment to obtain the laser additive manufacturing aging steel. The alloy is further subjected to heat treatment, and a B2 phase can be directionally separated out. According to the method disclosed by the invention, the problem of composition segregation of the traditional casting FeCrNiAlTi alloy is solved, the laser additive manufacturing aging steel with uniform composition and excellent performance is prepared, and the requirements on high-performance metal materials in the fields of high-end equipment manufacturing and the like are met.

Description

Technical Field

[0001] This invention relates to the field of metal material processing technology, and more specifically to a laser additive manufacturing method and application for aging steel and heat treatment, particularly applicable to the field of optimizing alloy strength, toughness and environmental adaptability by controlling B2 phase precipitation through selective laser melting (SLM) combined with specific heat treatment. Background Technology

[0002] In the application of metallic materials, FeCrNiAlTi alloy has important application value in aerospace, energy equipment, chemical industry and other fields due to its excellent high temperature resistance, oxidation resistance and potential corrosion resistance, and has become one of the research hotspots of high performance metallic materials in recent years.

[0003] With the development of additive manufacturing technology, selective laser melting (SLM) has been applied to the preparation of FeCrNiAlTi alloys due to its advantages of high-precision forming of complex structures, reduced material waste, and rapid near-net-shape forming. This has, to some extent, solved problems in traditional casting processes such as compositional segregation and coarse grains caused by uneven cooling rates and solute redistribution, resulting in an initial improvement in the uniformity and density of the alloy microstructure. However, existing publicly available SLM techniques for preparing FeCrNiAlTi alloys still face key technical bottlenecks that urgently need to be overcome, making it difficult to meet the stringent requirements of high-end equipment for the synergistic properties of high strength, high toughness, and long-term stability.

[0004] In FeCrNiAlTi alloys, the B2 phase, as a potential high-efficiency strengthening phase, has a decisive influence on the alloy's high-temperature strength, creep resistance, and corrosion resistance due to its precipitation morphology, dispersion, and distribution. When the B2 phase is uniformly dispersed in the matrix at the nanoscale, it can significantly improve the strength through "ordered strengthening" and "coherent strain strengthening," and its chemical stability can also improve the alloy's surface protection ability under high-temperature oxidation and corrosion environments. However, none of the currently disclosed SLM techniques for preparing FeCrNiAlTi alloys have achieved directional control of the B2 phase. Summary of the Invention

[0005] To address the above problems, this invention provides a laser additive manufacturing (SLM) method for preparing and heat-treating age-hardening steel, and its application. The SLM-manufactured age-hardening steel is a novel FeCrNiAlTi alloy. The method of this invention solves the problem of compositional segregation in traditional cast FeCrNiAlTi alloys, producing a novel FeCrNiAlTi alloy with uniform composition and excellent performance. By optimizing the alloy composition design, specifically the ratio of Al (2.0%~2.5%) to Ti (1.0%~1.5%), the nucleation sites of the B2 phase ((Fe,Ni)Al) are increased; the interference of oxide inclusions on the precipitation of the B2 phase is reduced, laying the compositional foundation for the nanoscale dispersion of the B2 phase during subsequent heat treatment. The synergistic control of SLM process parameters and customized heat treatment achieves the directional precipitation and uniform distribution of the B2 phase, solving the problems of strength-toughness imbalance, insufficient high-temperature stability, and poor process adaptability in existing technologies.

[0006] The first objective of this invention is to provide a heat treatment method for preparing laser additive manufacturing aged steel, comprising the following steps: Weigh each raw material powder according to the following mass percentages: Fe 40%–50%, Cr 10%–18%, Ni 22%–32%, Al 2.0%–2.5%, and Ti 1.0%–1.5%, totaling 100%.

[0007] The weighed raw material powder is pre-melted to obtain a master alloy ingot with uniform and dense composition; the master alloy ingot is then used to prepare alloy powder by aerosol method.

[0008] This invention utilizes an atomization method to prepare alloy powder, effectively ensuring the uniformity of the powder's chemical composition and optimizing its morphology and flowability. Furthermore, the atomization process is conducted in argon gas, effectively preventing oxidation caused by contact between the melt and air, thus improving powder purity. Powder prepared by this atomization method meets the requirements of additive manufacturing for powder flowability, filling performance, and printing uniformity, eliminating defects that may occur during the printing process and improving product density.

[0009] Under an inert gas protective environment, alloy powder is processed using selective laser melting to obtain FeCrNiAlTi alloy material. The FeCrNiAlTi alloy material is then heat-treated to obtain laser additive manufacturing aging steel containing the B2 phase.

[0010] Preferably, the raw material powders are weighed according to the following mass percentages: Fe 48.52%–49.06%, Cr 16.28%–16.98%, Ni 30.82%–31.41%, Al 2.05%–2.4%, and Ti 1.04%–1.44%, totaling 100%. In a preferred embodiment of the present invention, during laser selective melting, the laser power is 110W to 300W, and the scanning speed is 800mm / s to 1800mm / s. When the laser power is between 110W and 300W and the scanning speed is between 800mm / s and 1600mm / s, the bulk energy density can be ensured to be within the range of sufficient melting without overheating, thus balancing density and grain refinement.

[0011] When performing subsequent heat treatment, the heat treatment conditions are 550℃~600℃ and the holding time is 600min~720min; the preferred holding temperature is 580℃ and the holding time is 600min, which will cause the B2 phase to precipitate in a directional manner.

[0012] In a preferred embodiment of the present invention, the scanning interval is 80μm to 100μm during laser selective melting. The scanning interval of 80μm to 100μm is suitable for powder particle size (15μm-45μm), ensuring effective overlap of adjacent molten pools and guaranteeing the continuity and uniformity of the formed part.

[0013] In a preferred embodiment of the present invention, the particle size of the alloy powder is 15μm to 45μm, and the oxygen content is ≤500ppm. 15μm to 45μm is the typical suitable range for SLM (Small Metal Melting). If the particle size is too small, it is easy to float and has poor flowability; if the particle size is too large, the energy required for melting is high, and unmelted particles are easy to remain. This range can ensure good powder spreadability and uniform melting.

[0014] In a preferred embodiment of the present invention, the aerosol processing step is as follows: The weighed powder is pre-melted to obtain a master alloy ingot; the master alloy ingot is then melted in an inert gas atmosphere to obtain a melt; the melt is then atomized to obtain alloy powder. The combination of pre-melting for impurity removal and high-temperature homogenization ensures uniform composition of the master alloy ingot, providing a prerequisite for consistent composition in subsequent atomization powder production. Atomization in an inert gas atmosphere avoids oxidation (especially of active elements such as Al and Ti) caused by contact between the melt and air, further controlling the oxygen content of the powder. Simultaneously, inert gas atomization yields powder with high sphericity and good flowability, meeting the powder spreading requirements of SLM (Small Induction Melting).

[0015] In a preferred embodiment of the present invention, the melting temperature is 1670℃~1690℃, the melting time is 10min~15min each time, and the melting is performed 3 to 4 times.

[0016] In a preferred embodiment of the present invention, the pre-melting current is 250A to 300A, the melting time is 4min to 6min, and the number of melting times is 4 to 5.

[0017] In a preferred embodiment of the present invention, the substrate is preheated to 180°C–200°C before laser selective melting (SLM). Preheating the substrate to 180–200°C effectively alleviates thermal stress and prevents excessive grain growth, thus adapting to the rapid solidification characteristics of SLM. It also reduces the temperature difference between the molten pool and the substrate, thereby minimizing thermal stress and deformation.

[0018] The second objective of this invention is to provide laser additive manufacturing aging steel prepared by the above-described heat treatment method.

[0019] A third objective of this invention is to provide the application of the aforementioned laser additive manufacturing aging steel in the preparation of alloy parts and part coatings. For example, laser additive manufacturing aging steel is used to prepare high-strength parts (manufacturing key components such as crankshafts and connecting rods for automobile engines), high-temperature resistant parts (high-temperature components of engines, such as combustion chambers and turbine blades), high-temperature coatings (surface coatings for power plant boiler pipes, which can improve the pipes' resistance to high-temperature corrosion), and wear-resistant parts (hammers for crushers, liners for ball mills, etc., which require frequent contact with materials such as ores).

[0020] Compared with the prior art, the present invention has the following beneficial effects: By employing specific alloy design and heat treatment processes in laser additive manufacturing of aging steel, the following significant effects can be achieved: (1) Microstructure optimization: Traditional casting alloys suffer from compositional segregation and uneven structure, resulting in coarse grains. First, through a pre-melting step, the mixed powder with uneven composition and impurities is transformed into a uniform, pure, and dense master alloy ingot, providing a stable and high-quality molten raw material for gas atomization. Finally, a new type of FeCrNiAlTi alloy powder suitable for additive manufacturing (i.e., laser additive manufacturing aging steel) is produced. If the pre-melting step is omitted and gas atomization is performed directly, even with subsequent optimization of process parameters, it is difficult to solve the problems of powder compositional segregation, low purity, and wide particle size distribution. Ultimately, the additive manufactured parts have low density and large fluctuations in mechanical properties. Then, during the additive manufacturing process, the rapid laser scanning causes the powder to melt and solidify instantly. The solidification speed is extremely fast, which greatly shortens the element diffusion time and suppresses solute redistribution and gravity segregation. At the same time, the layer-by-layer stacking manufacturing method allows each layer of alloy to solidify rapidly in a relatively independent environment, avoiding the large-scale compositional inhomogeneity phenomenon in traditional casting. Due to their uniform composition and rapid solidification, additively manufactured alloys exhibit significantly refined grains, resulting in a smaller average grain size and a denser microstructure. This fine and uniform microstructure enhances the alloy's strength and toughness. Specifically, heat treatment at 580℃ for 600 minutes induces the directional precipitation of the B2 phase. This phase, uniformly dispersed in the matrix at nanoscale dimensions, further optimizes the strengthening effect of the microstructure, laying a core foundation for performance improvement.

[0021] (2) Enhanced mechanical properties: Additive manufacturing can significantly improve the tensile strength, yield strength and fatigue resistance of the alloy. The B2 phase precipitated by heat treatment at 580℃ for 600 minutes can form a synergistic strengthening effect with the fine grain structure and dislocation structure, further improving the upper limit of the mechanical properties of the alloy, thereby meeting higher application requirements.

[0022] (3) Excellent wear resistance: The hardness of FeCrNiAlTi alloy can effectively improve the wear resistance of the alloy, and the B2 phase precipitated by heat treatment itself has high hardness, which can further enhance the wear resistance of the material surface and extend its service life, making it particularly suitable for applications in high wear environments.

[0023] (4) Economic efficiency of preparation: It can effectively reduce the problem of component segregation in traditional processes, reduce the dependence on complex molds, shorten the manufacturing cycle, and achieve stable precipitation of B2 phase through precise heat treatment process (580℃, 600 minutes), without the need for additional complex processes, improve material utilization, and has significant economic benefits and engineering application value.

[0024] (5) Improve process adaptability: This alloy has good process adaptability. It can not only be adapted to additive manufacturing process, but its heat treatment precipitation of B2 phase can also be combined with the performance optimization requirements of various alloy systems, which helps to expand the application range. Attached Figure Description

[0025] Figure 1 The image shown is a SEM image of the FeCrNiAlTi powder prepared in Example 1 of this invention. The inset is a magnified view of a portion of the image.

[0026] Figure 2 EDS elemental analysis of FeCrNiAlTi powder. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Selective Laser Melting (SLM) is a type of additive manufacturing technology. Its basic principle is to use a high-energy-density laser beam to selectively melt alloy powder layer by layer according to a pre-designed three-dimensional model. In the forming process, a uniform layer of alloy powder is first spread on a substrate. The laser beam scans and melts the powder in specific areas based on the model's slice data, causing the powder to rapidly melt and solidify, forming a solid layer consistent with the shape of the model slice. Then, by lowering the worktable or raising the powder spreader to a certain height, powder is spread again, and the melting and solidification process is repeated. This layer-by-layer accumulation ultimately forms a complete three-dimensional part.

[0029] Example 1 Step 1: Weigh the elements according to the following mass percentages: Fe 49.06%, Cr 16.28%, Ni 30.82%, Al 2.4%, and Ti 1.44%. Prepare alloy powder with a particle size of 15-45 μm and an oxygen content ≤500 ppm using a gas atomization method. The specific preparation steps are as follows.

[0030] 1.1. Raw material pretreatment and purity assurance: Use elemental metals with a purity of ≥99.95% (such as Fe, Cr, Ni). For easily oxidized elements (such as Al, Ti), use high-purity raw materials that are vacuum-packed to avoid the formation of surface oxide films.

[0031] The raw materials are precisely weighed according to the alloy composition, and then placed in an argon-protected electric arc furnace with a vacuum degree ≤10. -4 Pa, gas pressure 0.05MPa, current 300A, melting time 4 minutes per melting; melting times 4 times, pre-melting into master alloy ingots to ensure uniform composition, and then sanding the surface of the ingots after pre-melting to remove the oxide layer.

[0032] 1.2. Preparation of the atomization system: The atomization chamber was evacuated to 5×10 -3 The pressure was maintained at 30 Pa for 30 minutes, then purged with 99.9995% high-purity argon gas; this vacuum-purging cycle was repeated four times until the oxygen partial pressure in the atomization chamber was ≤5×10⁻⁶. -5 Pa.

[0033] 1.3. Alloy smelting: The master alloy ingot is placed in a crucible and melted by medium-frequency induction heating under argon protection. The temperature is raised to 150±10°C above the alloy liquidus line (1530°C). In this embodiment, the temperature is raised to 1680°C and then held for 10 minutes. The total number of melting times is 4. During this period, the alloy liquid is stirred with a graphite rod to ensure uniform composition.

[0034] 1.4. Powder cooling: A secondary cooling zone is set up at the bottom of the atomization chamber, and low-temperature argon gas at -196℃ is introduced to increase the powder cooling rate to 10. 5 K / s, inhibits oxidation on the particle surface and allows the powder to cool to room temperature.

[0035] The powder, cooled to room temperature, was evenly poured onto a vibrating sieve. The vibration frequency of the sieve was set to 40Hz, the ultrasonic power to 60W, and the sieving time to 15 minutes. After sieving, the 15-45μm target powder was gently swept into a clean container and then placed in a vacuum drying oven at 80℃ for 4 hours to remove moisture and impurities, yielding FeCrNiAlTi alloy material powder.

[0036] Step 2: Load the model and set up the printer for printing: Printing is performed using a selective laser melting (SLM) device. Before operating the device, check the focusing of the optical path, the flatness of the powder spreading roller, and the sealing of the argon gas protection path. Preheat the substrate to 200℃. The additive manufacturing method used for this FeCrNiAlTi alloy material powder is selective laser melting (SLM) technology. The processed FeCrNiAlTi alloy material powder is evenly spread on the printing platform to form a thin powder layer. The laser power is set to 130W, the scanning speed to 800mm / s, the scanning interval to 80μm, and 99.99% pure argon gas is introduced. The laser beam scans and melts the powder layer by layer according to the scanning path generated by the slicing software, causing the powder to accumulate and solidify layer by layer, gradually forming the shape under the protection of argon gas.

[0037] The specific steps are as follows: 2.1. 3D Model Design and Slicing Processing: Based on the structural requirements of the parts, the model was imported into the SLM-specific slicing software using CAD software. The scanning power, scanning time, and scanning spacing were set for printing, and scanning was performed using "bidirectional parallel lines + 67° rotation between layers".

[0038] 2.2. Pretreatment of FeCrNiAlTi alloy powder: The powder was sieved using a sieve inside an argon-protected glove box to remove agglomerated particles and impurities, ensuring that the powder particle size was concentrated between 15-45 μm. The powder was then placed in a vacuum drying oven and dried for 5 hours to remove adsorbed moisture and gases.

[0039] 2.3. Equipment Debugging: The substrate was preheated to 200°C, and 99.999% high-purity argon gas was introduced to replace the air in the printing chamber three times, resulting in a final oxygen content ≤100ppm. The pretreated FeCrNiAlTi powder was then evenly spread onto the substrate to form the first powder layer. The scanning parameters were set as follows: laser power 130W; scanning speed: 800mm / s; scanning spacing: 80μm. After each layer was scanned, the printing platform descended by one layer thickness, and the powder spreading device spread powder again. This scanning process was repeated to obtain 148 printed layers, with the scanning direction of adjacent layers rotated by 67°.

[0040] 2.4. Post-processing stage: After printing, maintain an argon atmosphere and allow the parts to cool to below 100°C within the printing chamber (to prevent rapid cooling and thermal stress cracking). Open the chamber door and use a special tool to remove the substrate and parts together, removing excess powder for recycling.

[0041] The finished product was wire-cut into rod-shaped tensile samples with dimensions of 30mm*7mm*2mm. Then, a heat treatment experiment was conducted, with the holding temperature set at 580℃ and the holding time at 600 minutes, yielding laser additive manufacturing aging steel.

[0042] The laser additive manufacturing of aged steel samples yielded an average grain size of 8.43 μm, a yield strength of 755 MPa, and a tensile strength of 877 MPa.

[0043] Example 2 Step 1: Weigh the elements according to the following mass percentages: Fe 49.06%, Cr 16.28%, Ni 30.82%, Al 2.4%, and Ti 1.44%. Prepare alloy powder with a particle size of 15-45 μm and an oxygen content ≤500 ppm using a gas atomization method. The specific preparation steps are as follows.

[0044] 1.1. Raw material pretreatment and purity assurance: Use elemental metals with a purity of ≥99.95% (such as Fe, Cr, Ni). For easily oxidized elements (such as Al, Ti), use high-purity raw materials that are vacuum-packed to avoid the formation of surface oxide films.

[0045] The raw materials are precisely weighed according to the alloy composition, and then placed in an argon-protected electric arc furnace with a vacuum degree ≤10. -4 Pa, gas pressure is 0.05MPa, current is 300A, each melting time is 4 minutes; the number of melting cycles is 4 minutes, pre-melting into a master alloy ingot to ensure uniform composition, and after pre-melting, the surface of the ingot is polished with sandpaper to remove the oxide layer.

[0046] 1.2. Preparation of the atomization system: The atomization chamber was evacuated to 5×10 -3The pressure was maintained at 30 Pa for 30 minutes, then purged with 99.9995% high-purity argon gas; this vacuum-purging cycle was repeated four times until the oxygen partial pressure in the atomization chamber was ≤5×10⁻⁶. -5 Pa.

[0047] 1.3. Alloy smelting: The master alloy ingot is placed in a crucible and melted by medium-frequency induction heating under argon protection. The temperature is raised to 150±10°C above the alloy liquidus line (1530°C). In this embodiment, the temperature is raised to 1680°C and then held for 10 minutes. The total number of melting times is 4. During this period, the alloy liquid is stirred with a graphite rod to ensure uniform composition.

[0048] 1.4. Powder cooling: A secondary cooling zone is set up at the bottom of the atomization chamber, and low-temperature argon gas at -196℃ is introduced to increase the powder cooling rate to 10. 5 K / s, inhibits oxidation on the particle surface and allows the powder to cool to room temperature.

[0049] The powder, cooled to room temperature, was evenly poured onto a vibrating sieve. The vibration frequency of the sieve was set to 40Hz, the ultrasonic power to 60W, and the sieving time to 15 minutes. After sieving, the 15-45μm target powder was gently swept into a clean container and then placed in a vacuum drying oven at 80℃ for 4 hours to remove moisture and impurities, yielding FeCrNiAlTi alloy material powder.

[0050] Step 2: Load the model and set up the printer for printing: Printing is performed using a selective laser melting (SLM) device. Before operating the device, check the focusing of the optical path, the flatness of the powder spreading roller, and the sealing of the argon gas protection path. Preheat the substrate to 200℃. The additive manufacturing method used for this FeCrNiAlTi alloy material powder is selective laser melting (SLM) technology. The processed FeCrNiAlTi material powder is evenly spread on the printing platform to form a thin powder layer. Set the laser power to 130W, the scanning speed to 800mm / s, the scanning interval to 80μm, and introduce 99.99% pure argon gas. The laser beam scans and melts the powder layer by layer according to the scanning path generated by the slicing software, causing the powder to accumulate and solidify layer by layer, gradually forming the shape under the protection of argon gas.

[0051] The specific steps are as follows: 2.1. 3D Model Design and Slicing Processing: Based on the structural requirements of the parts, the model was imported into the SLM-specific slicing software using CAD software. The scanning power, scanning time, and scanning spacing were set for printing, and scanning was performed using "bidirectional parallel lines + 67° rotation between layers".

[0052] 2.2. Pretreatment of FeCrNiAlTi alloy powder: The powder was sieved using a sieve inside an argon-protected glove box to remove agglomerated particles and impurities, ensuring that the powder particle size was concentrated between 15-45 μm. The powder was then placed in a vacuum drying oven and dried for 5 hours to remove adsorbed moisture and gases.

[0053] 2.3. Equipment Debugging: The substrate was preheated to 200°C, and 99.99% high-purity argon gas was introduced to replace the air in the printing chamber three times, resulting in a final oxygen content ≤100ppm. Pretreated FeCrNiAlTi powder was then evenly spread onto the substrate to form the first powder layer. The scanning parameters were set as follows: laser power 130W; scanning speed: 800mm / s; scanning spacing: 80μm. After each layer was scanned, the printing platform descended by one layer thickness, and the powder spreading device spread powder again. This scanning process was repeated to obtain 148 printed layers, with the scanning direction of adjacent layers rotated by 67°.

[0054] 2.4. Post-processing stage: After printing, maintain an argon atmosphere and allow the parts to cool to below 100°C within the printing chamber (to prevent rapid cooling and thermal stress cracking). Open the chamber door and use a special tool to remove the substrate and parts together, removing excess powder for recycling.

[0055] The finished product was wire-cut into rod-shaped tensile samples with dimensions of 30mm*7mm*2mm. Then, a heat treatment experiment was conducted, with the holding temperature set at 480℃ and the holding time at 600 minutes, yielding laser additive manufacturing aging steel.

[0056] The laser additive manufacturing of aged steel samples yielded an average grain size of 13.33 μm, a yield strength of 728 MPa, and a tensile strength of 843 MPa.

[0057] Example 3 Step 1: Weigh the elements according to the following mass percentages: Fe 49.06%, Cr 16.28%, Ni 30.82%, Al 2.4%, and Ti 1.44%. Prepare alloy powder with a particle size of 15-45 μm and an oxygen content ≤500 ppm using a gas atomization method. The specific preparation steps are as follows.

[0058] 1.1. Raw material pretreatment and purity assurance: Use elemental metals with a purity of ≥99.95% (such as Fe, Cr, Ni). For easily oxidized elements (such as Al, Ti), use high-purity raw materials that are vacuum-packed to avoid the formation of surface oxide films.

[0059] The raw materials are precisely weighed according to the alloy composition, and then placed in an argon-protected electric arc furnace with a vacuum degree ≤10. -4Pa, gas pressure 0.05MPa, current 300A, melting time 4 minutes per melting; melting times 4 times, pre-melting into master alloy ingots to ensure uniform composition, and then sanding the surface of the ingots after pre-melting to remove the oxide layer.

[0060] 1.2. Preparation of the atomization system: The atomization chamber was evacuated to 5×10 -3 The pressure was maintained at 30 Pa for 30 minutes, then purged with 99.9995% high-purity argon gas; this vacuum-purging cycle was repeated four times until the oxygen partial pressure in the atomization chamber was ≤5×10⁻⁶. -5 Pa.

[0061] 1.3. Alloy smelting: The master alloy ingot is placed in a crucible and melted by medium-frequency induction heating under argon protection. The temperature is raised to 150±10°C above the alloy liquidus line (1530°C). In this embodiment, the temperature is raised to 1680°C and then held for 10 minutes. The total number of melting times is 4. During this period, the alloy liquid is stirred with a graphite rod to ensure uniform composition.

[0062] 1.4. Powder cooling: A secondary cooling zone is set up at the bottom of the atomization chamber, and low-temperature argon gas at -196℃ is introduced to increase the powder cooling rate to 10. 5 K / s, inhibits oxidation on the particle surface and allows the powder to cool to room temperature.

[0063] The powder, cooled to room temperature, was evenly poured onto a vibrating sieve. The vibration frequency of the sieve was set to 40Hz, the ultrasonic power to 60W, and the sieving time to 15 minutes. After sieving, the 15-45μm target powder was gently swept into a clean container and then placed in a vacuum drying oven at 80℃ for 4 hours to remove moisture and impurities, yielding FeCrNiAlTi alloy material powder.

[0064] Step 2: Load the model and set up the printer for printing: Printing is performed using a selective laser melting (SLM) device. Before operating the device, check the focusing of the optical path, the flatness of the powder spreading roller, and the sealing of the argon gas protection path. Preheat the substrate to 200℃. The additive manufacturing method used for this FeCrNiAlTi alloy material powder is selective laser melting (SLM) technology. The processed FeCrNiAlTi alloy material powder is evenly spread on the printing platform to form a thin powder layer. The laser power is set to 130W, the scanning speed to 800mm / s, the scanning interval to 80μm, and 99.99% pure argon gas is introduced. The laser beam scans and melts the powder layer by layer according to the scanning path generated by the slicing software, causing the powder to accumulate and solidify layer by layer, gradually forming the shape under the protection of argon gas.

[0065] The specific steps are as follows: 2.1. 3D Model Design and Slicing Processing: Based on the structural requirements of the parts, the model was imported into the SLM-specific slicing software using CAD software. The scanning power, scanning time, and scanning spacing were set for printing, and scanning was performed using "bidirectional parallel lines + 67° rotation between layers".

[0066] 2.2. Pretreatment of FeCrNiAlTi alloy powder: The powder was sieved using a sieve inside an argon-protected glove box to remove agglomerated particles and impurities, ensuring that the powder particle size was concentrated between 15-45 μm. The powder was then placed in a vacuum drying oven and dried for 5 hours to remove adsorbed moisture and gases.

[0067] 2.3. Equipment Debugging: The substrate was preheated to 200°C, and 99.999% high-purity argon gas was introduced to replace the air in the printing chamber three times, resulting in a final oxygen content ≤100ppm. The pretreated FeCrNiAlTi powder was then evenly spread onto the substrate to form the first powder layer. The scanning parameters were set as follows: laser power 130W; scanning speed: 800mm / s; scanning spacing: 80μm. After each layer was scanned, the printing platform descended by one layer thickness, and the powder spreading device spread powder again. This scanning process was repeated to obtain 148 printed layers, with the scanning direction of adjacent layers rotated by 67°.

[0068] 2.4. Post-processing stage: After printing, maintain an argon atmosphere and allow the parts to cool to below 100°C within the printing chamber (to prevent rapid cooling and thermal stress cracking). Open the chamber door and use a special tool to remove the substrate and parts together, removing excess powder for recycling.

[0069] The finished product was wire-cut into rod-shaped tensile samples with dimensions of 30mm*7mm*2mm. Then, a heat treatment experiment was conducted, with the holding temperature set at 630℃ and the holding time at 600 minutes, yielding laser additive manufacturing aging steel.

[0070] The laser additive manufacturing of aged steel samples yielded an average grain size of 15.47 μm, a yield strength of 700 MPa, and a tensile strength of 869 MPa.

[0071] Example 4 Step 1: Weigh the elements according to the following mass percentages: Fe 49.06%, Cr 16.28%, Ni 30.82%, Al 2.4%, and Ti 1.44%. Prepare alloy powder with a particle size of 15-45 μm and an oxygen content ≤500 ppm using a gas atomization method. The specific preparation steps are as follows.

[0072] 1.1. Raw material pretreatment and purity assurance: Use elemental metals with a purity of ≥99.95% (such as Fe, Cr, Ni). For easily oxidized elements (such as Al, Ti), use high-purity raw materials that are vacuum-packed to avoid the formation of surface oxide films.

[0073] The raw materials are precisely weighed according to the alloy composition, and then placed in an argon-protected electric arc furnace with a vacuum degree ≤10. -4 Pa, gas pressure 0.05MPa, current 300A, melting time 4 minutes per melting; melting times 4 times, pre-melting into master alloy ingots to ensure uniform composition, and then sanding the surface of the ingots after pre-melting to remove the oxide layer.

[0074] 1.2. Preparation of the atomization system: The atomization chamber was evacuated to 5×10 -3 The pressure was maintained at 30 Pa for 30 minutes, then purged with 99.9995% high-purity argon gas; this vacuum-purging cycle was repeated four times until the oxygen partial pressure in the atomization chamber was ≤5×10⁻⁶. -5 Pa.

[0075] 1.3. Alloy smelting: The master alloy ingot is placed in a crucible and melted by medium-frequency induction heating under argon protection. The temperature is raised to 150±10°C above the alloy liquidus line (1530°C). In this embodiment, the temperature is raised to 1680°C and then held for 10 minutes. The total number of melting times is 4. During this period, the alloy liquid is stirred with a graphite rod to ensure uniform composition.

[0076] 1.4. Powder cooling: A secondary cooling zone is set up at the bottom of the atomization chamber, and low-temperature argon gas at -196℃ is introduced to increase the powder cooling rate to 10. 5 K / s, inhibits oxidation on the particle surface and allows the powder to cool to room temperature.

[0077] The powder, cooled to room temperature, was evenly poured onto a vibrating sieve. The vibration frequency of the sieve was set to 40Hz, the ultrasonic power to 60W, and the sieving time to 15 minutes. After sieving, the 15-45μm target powder was gently swept into a clean container and then placed in a vacuum drying oven at 80℃ for 4 hours to remove moisture and impurities, yielding FeCrNiAlTi alloy material powder.

[0078] Step 2: Load the model and set up the printer for printing: Printing is performed using a selective laser melting (SLM) device. Before operating the device, check the focusing of the optical path, the flatness of the powder spreading roller, and the sealing of the argon gas protection path. Preheat the substrate to 200℃. The additive manufacturing method used for this FeCrNiAlTi alloy material powder is selective laser melting (SLM) technology. The processed FeCrNiAlTi alloy material powder is evenly spread on the printing platform to form a thin powder layer. The laser power is set to 170W, the scanning speed to 1000mm / s, the scanning interval to 80μm, and argon gas with a purity of 99.99% is introduced. The laser beam scans and melts the powder layer by layer according to the scanning path generated by the slicing software, causing the powder to accumulate and solidify layer by layer, gradually forming the shape under the protection of argon gas.

[0079] The specific steps are as follows: 2.1. 3D Model Design and Slicing Processing: Based on the structural requirements of the parts, the model was imported into the SLM-specific slicing software using CAD software. The scanning power, scanning time, and scanning spacing were set for printing, and scanning was performed using "bidirectional parallel lines + 67° rotation between layers".

[0080] 2.2. Pretreatment of FeCrNiAlTi alloy powder: The powder was sieved using a sieve inside an argon-protected glove box to remove agglomerated particles and impurities, ensuring that the powder particle size was concentrated between 15-45 μm. The powder was then placed in a vacuum drying oven and dried for 5 hours to remove adsorbed moisture and gases.

[0081] 2.3. Equipment Debugging: The substrate was preheated to 200°C, and 99.999% high-purity argon gas was introduced to replace the air in the printing chamber three times, resulting in a final oxygen content ≤100ppm. The pretreated FeCrNiAlTi powder was then evenly spread onto the substrate to form the first powder layer. The scanning parameters were set as follows: laser power 170W; scanning speed: 1000mm / s; scanning spacing: 80μm. After each layer was scanned, the printing platform descended by one layer thickness, and the powder spreading device spread powder again. This scanning process was repeated to obtain 148 printed layers, with the scanning direction of adjacent layers rotated by 67°.

[0082] 2.4. Post-processing stage: After printing, maintain an argon atmosphere and allow the parts to cool to below 100°C within the printing chamber (to prevent rapid cooling and thermal stress cracking). Open the chamber door and use a special tool to remove the substrate and parts together, removing excess powder for recycling.

[0083] The finished product was wire-cut into rod-shaped tensile samples with dimensions of 30mm*7mm*2mm. Then, a heat treatment experiment was conducted, with the holding temperature set at 580℃ and the holding time at 600 minutes, yielding laser additive manufacturing aging steel.

[0084] The laser additive manufacturing of aged steel samples yielded an average grain size of 19.81 μm, a yield strength of 688 MPa, and a tensile strength of 854 MPa.

[0085] Example 5 Step 1: Weigh the elements according to the following mass percentages: Fe 49.06%, Cr 16.28%, Ni 30.82%, Al 2.4%, and Ti 1.44%. Prepare alloy powder with a particle size of 15-45 μm and an oxygen content ≤500 ppm using a gas atomization method. The specific preparation steps are as follows.

[0086] 1.1. Raw material pretreatment and purity assurance: Use elemental metals with a purity of ≥99.95% (such as Fe, Cr, Ni). For easily oxidized elements (such as Al, Ti), use high-purity raw materials that are vacuum-packed to avoid the formation of surface oxide films.

[0087] The raw materials are precisely weighed according to the alloy composition, and then placed in an argon-protected electric arc furnace with a vacuum degree ≤10. -4 Pa, gas pressure 0.05MPa, current 300A, melting time 4 minutes per melting; melting times 4 times, pre-melting into master alloy ingots to ensure uniform composition, and then sanding the surface of the ingots after pre-melting to remove the oxide layer.

[0088] 1.2. Preparation of the atomization system: The atomization chamber was evacuated to 5×10 -3 The pressure was maintained at 30 Pa for 30 minutes, then purged with 99.9995% high-purity argon gas; this vacuum-purging cycle was repeated four times until the oxygen partial pressure in the atomization chamber was ≤5×10⁻⁶. -5 Pa.

[0089] 1.3. Alloy smelting: The master alloy ingot is placed in a crucible and melted by medium-frequency induction heating under argon protection. The temperature is raised to 150±10°C above the alloy liquidus line (1530°C). In this embodiment, the temperature is raised to 1680°C and then held for 10 minutes. The total number of melting times is 4. During this period, the alloy liquid is stirred with a graphite rod to ensure uniform composition.

[0090] 1.4. Powder cooling: A secondary cooling zone is set up at the bottom of the atomization chamber, and low-temperature argon gas at -196℃ is introduced to increase the powder cooling rate to 10. 5 K / s, inhibits oxidation on the particle surface and allows the powder to cool to room temperature.

[0091] The powder, cooled to room temperature, was evenly poured onto a vibrating sieve. The vibration frequency of the sieve was set to 40Hz, the ultrasonic power to 60W, and the sieving time to 15 minutes. After sieving, the 15-45μm target powder was gently swept into a clean container and then placed in a vacuum drying oven at 80℃ for 4 hours to remove moisture and impurities, yielding FeCrNiAlTi alloy material powder.

[0092] Step 2: Load the model and set up the printer for printing: Printing is performed using a selective laser melting (SLM) device. Before operating the device, check the focusing of the optical path, the flatness of the powder spreading roller, and the sealing of the argon gas protection path. Preheat the substrate to 200℃. The additive manufacturing method used for this FeCrNiAlTi alloy material powder is selective laser melting (SLM) technology. The processed FeCrNiAlTi alloy material powder is evenly spread on the printing platform to form a thin powder layer. The laser power is set to 260W, the scanning speed to 1778mm / s, the scanning interval to 90μm, and argon gas with a purity of 99.99% is introduced. The laser beam scans and melts the powder layer by layer according to the scanning path generated by the slicing software, causing the powder to accumulate and solidify layer by layer, gradually forming the shape under the protection of argon gas.

[0093] The specific steps are as follows: 2.1. 3D Model Design and Slicing Processing: Based on the structural requirements of the parts, the model was imported into the SLM-specific slicing software using CAD software. The scanning power, scanning time, and scanning spacing were set for printing, and scanning was performed using "bidirectional parallel lines + 67° rotation between layers".

[0094] 2.2. Pretreatment of FeCrNiAlTi alloy powder: The powder was sieved using a sieve inside an argon-protected glove box to remove agglomerated particles and impurities, ensuring that the powder particle size was concentrated between 15-45 μm. The powder was then placed in a vacuum drying oven and dried for 5 hours to remove adsorbed moisture and gases.

[0095] 2.3. Equipment Debugging: The substrate was preheated to 200°C, and 99.999% high-purity argon gas was introduced to replace the air in the printing chamber three times, resulting in a final oxygen content ≤100ppm. The pretreated FeCrNiAlTi powder was then evenly spread onto the substrate to form the first powder layer. The scanning parameters were set as follows: laser power 260W; scanning speed: 1778mm / s; scanning spacing: 90μm. After each layer was scanned, the printing platform descended by one layer thickness, and the powder spreading device spread powder again. This scanning process was repeated to obtain 148 printed layers, with the scanning direction of adjacent layers rotated by 67°.

[0096] 2.4. Post-processing stage: After printing, maintain an argon atmosphere and allow the parts to cool to below 100°C within the printing chamber (to prevent rapid cooling and thermal stress cracking). Open the chamber door and use a special tool to remove the substrate and parts together, removing excess powder for recycling.

[0097] The finished product was wire-cut into rod-shaped tensile samples with dimensions of 30mm*7mm*2mm. Then, a heat treatment experiment was conducted, with the holding temperature set at 580℃ and the holding time at 600 minutes, yielding laser additive manufacturing aging steel.

[0098] The laser additive manufacturing of aged steel samples yielded an average grain size of 13.57 μm, a yield strength of 599 MPa, and a tensile strength of 708 MPa.

[0099] Example 6 Step 1: Weigh the elements according to the following mass percentages: Fe 49.06%, Cr 16.28%, Ni 30.82%, Al 2.4%, and Ti 1.44%. Prepare alloy powder with a particle size of 15-45 μm and an oxygen content ≤500 ppm using a gas atomization method. The specific preparation steps are as follows.

[0100] 1.1. Raw material pretreatment and purity assurance: Use elemental metals with a purity of ≥99.95% (such as Fe, Cr, Ni). For easily oxidized elements (such as Al, Ti), use high-purity raw materials that are vacuum-packed to avoid the formation of surface oxide films.

[0101] The raw materials are precisely weighed according to the alloy composition, and then placed in an argon-protected electric arc furnace with a vacuum degree ≤10. -4 Pa, gas pressure 0.05MPa, current 300A, melting time 4 minutes per melting; melting times 4 times, pre-melting into master alloy ingots to ensure uniform composition, and then sanding the surface of the ingots after pre-melting to remove the oxide layer.

[0102] 1.2. Preparation of the atomization system: The atomization chamber was evacuated to 5×10 -3 The pressure was maintained at 30 Pa for 30 minutes, then purged with 99.9995% high-purity argon gas; this vacuum-purging cycle was repeated four times until the oxygen partial pressure in the atomization chamber was ≤5×10⁻⁶. -5 Pa.

[0103] 1.3. Alloy smelting: The master alloy ingot is placed in a crucible and melted by medium-frequency induction heating under argon protection. The temperature is raised to 150±10°C above the alloy liquidus line (1530°C). In this embodiment, the temperature is raised to 1680°C and then held for 10 minutes. The total number of melting times is 4. During this period, the alloy liquid is stirred with a graphite rod to ensure uniform composition.

[0104] 1.4. Powder cooling: A secondary cooling zone is set up at the bottom of the atomization chamber, and low-temperature argon gas at -196℃ is introduced to increase the powder cooling rate to 10. 5 K / s, inhibits oxidation on the particle surface and allows the powder to cool to room temperature.

[0105] The powder, cooled to room temperature, was evenly poured onto a vibrating sieve. The vibration frequency of the sieve was set to 40Hz, the ultrasonic power to 60W, and the sieving time to 15 minutes. After sieving, the 15-45μm target powder was gently swept into a clean container and then placed in a vacuum drying oven at 80℃ for 4 hours to remove moisture and impurities, yielding FeCrNiAlTi alloy material powder.

[0106] Step 2: Load the model and set up the printer for printing: Printing is performed using a selective laser melting (SLM) device. Before operating the device, check the focusing of the optical path, the flatness of the powder spreading roller, and the sealing of the argon gas protection path. Preheat the substrate to 200℃. The additive manufacturing method used for this FeCrNiAlTi alloy material powder is selective laser melting (SLM) technology. The processed FeCrNiAlTi alloy material powder is evenly spread on the printing platform to form a thin powder layer. Set the laser power to 300W, the scanning speed to 1600mm / s, the scanning interval to 100μm, and introduce 99.99% pure argon gas. The laser beam scans and melts the powder layer by layer according to the scanning path generated by the slicing software, causing the powder to accumulate and solidify layer by layer, gradually forming the shape under the protection of argon gas.

[0107] The specific steps are as follows: 2.1. 3D Model Design and Slicing Processing: Based on the structural requirements of the parts, the model was imported into the SLM-specific slicing software using CAD software. The scanning power, scanning time, and scanning spacing were set for printing, and scanning was performed using "bidirectional parallel lines + 67° rotation between layers".

[0108] 2.2. Pretreatment of FeCrNiAlTi alloy powder: The powder was sieved using a sieve inside an argon-protected glove box to remove agglomerated particles and impurities, ensuring that the powder particle size was concentrated between 15-45 μm. The powder was then placed in a vacuum drying oven and dried for 5 hours to remove adsorbed moisture and gases.

[0109] 2.3. Equipment Debugging: The substrate was preheated to 200°C, and 99.999% high-purity argon gas was introduced to replace the air in the printing chamber three times, resulting in a final oxygen content ≤100ppm. The pretreated FeCrNiAlTi powder was then evenly spread onto the substrate to form the first powder layer. The scanning parameters were set as follows: laser power 300W; scanning speed: 1600mm / s; scanning spacing: 100μm. After each layer was scanned, the printing platform descended by one layer thickness, and the powder spreading device spread powder again. This scanning process was repeated to obtain 148 printed layers, with the scanning direction of adjacent layers rotated by 67°.

[0110] 2.4. Post-processing stage: After printing, maintain an argon atmosphere and allow the parts to cool to below 100°C within the printing chamber (to prevent rapid cooling and thermal stress cracking). Open the chamber door and use a special tool to remove the substrate and parts together, removing excess powder for recycling.

[0111] The finished product was wire-cut into rod-shaped tensile samples with dimensions of 30mm*7mm*2mm. Then, a heat treatment experiment was conducted, with the holding temperature set at 580℃ and the holding time at 600 minutes, yielding laser additive manufacturing aging steel.

[0112] The laser additive manufacturing of aged steel samples yielded an average grain size of 15.41 μm, a yield strength of 659 MPa, and a tensile strength of 777 MPa.

[0113] Example 7 Step 1: Weigh the elements according to the following mass percentages: Fe 49.06%, Cr 16.28%, Ni 30.82%, Al 2.4%, and Ti 1.44%. Prepare alloy powder with a particle size of 15-45 μm and an oxygen content ≤500 ppm using a gas atomization method. The specific preparation steps are as follows.

[0114] 1.1. Raw material pretreatment and purity assurance: Use elemental metals with a purity of ≥99.95% (such as Fe, Cr, Ni). For easily oxidized elements (such as Al, Ti), use high-purity raw materials that are vacuum-packed to avoid the formation of surface oxide films.

[0115] The raw materials are precisely weighed according to the alloy composition, and then placed in an argon-protected electric arc furnace with a vacuum degree ≤10. -4 Pa, gas pressure 0.05MPa, current 250A, melting time 6 minutes per melting; melting times 5 times, pre-melting into master alloy ingots to ensure uniform composition, and then sanding the surface of the ingots to remove the oxide layer.

[0116] 1.2. Preparation of the atomization system: The atomization chamber was evacuated to 5×10 -3The pressure was maintained at 30 Pa for 30 minutes, then purged with 99.9995% high-purity argon gas; this vacuum-purging cycle was repeated four times until the oxygen partial pressure in the atomization chamber was ≤5×10⁻⁶. -5 Pa.

[0117] 1.3. Alloy smelting: The master alloy ingot is placed in a crucible and melted by medium-frequency induction heating under argon protection. The temperature is raised to 150±10°C above the alloy liquidus line (1530°C). In this embodiment, the temperature is raised to 1680°C and then held for 10 minutes. The total number of melting times is 4. During this period, the alloy liquid is stirred with a graphite rod to ensure uniform composition.

[0118] 1.4. Powder cooling: A secondary cooling zone is set up at the bottom of the atomization chamber, and low-temperature argon gas at -196℃ is introduced to increase the powder cooling rate to 10. 5 K / s, inhibits oxidation on the particle surface and allows the powder to cool to room temperature.

[0119] The powder, cooled to room temperature, was evenly poured onto a vibrating sieve. The vibration frequency of the sieve was set to 40Hz, the ultrasonic power to 60W, and the sieving time to 15 minutes. After sieving, the 15-45μm target powder was gently swept into a clean container and then placed in a vacuum drying oven at 80℃ for 4 hours to remove moisture and impurities, yielding FeCrNiAlTi alloy material powder.

[0120] Step 2: Load the model and set up the printer for printing: Printing is performed using a selective laser melting (SLM) device. Before operating the device, check the focusing of the optical path, the flatness of the powder spreading roller, and the sealing of the argon gas protection path. Preheat the substrate to 200°C. The additive manufacturing method used for this FeCrNiAlTi alloy material powder is selective laser melting (SLM) technology. The processed FeCrNiAlTi alloy material powder is evenly spread on the printing platform to form a thin powder layer. The laser power is set to 300W, the scanning speed to 1600mm / s, the scanning interval to 90μm, and 99.99% pure argon gas is introduced. The laser beam scans and melts the powder layer by layer according to the scanning path generated by the slicing software, causing the powder to accumulate and solidify layer by layer, gradually forming the shape under the protection of argon gas.

[0121] The specific steps are as follows: 2.1. 3D Model Design and Slicing Processing: Based on the structural requirements of the parts, the model was imported into the SLM-specific slicing software using CAD software. The scanning power, scanning time, and scanning spacing were set for printing, and scanning was performed using "bidirectional parallel lines + 67° rotation between layers".

[0122] 2.2. Pretreatment of FeCrNiAlTi alloy powder: The powder was sieved using a sieve inside an argon-protected glove box to remove agglomerated particles and impurities, ensuring that the powder particle size was concentrated between 15-45 μm. The powder was then placed in a vacuum drying oven and dried for 5 hours to remove adsorbed moisture and gases.

[0123] 2.3. Equipment Debugging: The substrate was preheated to 200°C, and 99.999% high-purity argon gas was introduced to replace the air in the printing chamber three times, resulting in a final oxygen content ≤100ppm. Pretreated FeCrNiAlTi powder was then evenly spread onto the substrate to form the first powder layer. The scanning parameters were set as follows: laser power 300W; scanning speed: 1600mm / s; scanning spacing: 90μm. After each layer was scanned, the printing platform descended by one layer thickness, and the powder spreading device spread powder again. This scanning process was repeated to obtain 148 printed layers, with the scanning direction of adjacent layers rotated by 67°.

[0124] 2.4. Post-processing stage: After printing, maintain an argon atmosphere and allow the parts to cool to below 100°C within the printing chamber (to prevent rapid cooling and thermal stress cracking). Open the chamber door and use a special tool to remove the substrate and parts together, removing excess powder for recycling.

[0125] The finished product was wire-cut into rod-shaped tensile samples with dimensions of 30mm*7mm*2mm. Then, a heat treatment experiment was conducted, with the holding temperature set at 580℃ and the holding time at 600 minutes, yielding laser additive manufacturing aging steel.

[0126] The laser additive manufacturing of aged steel samples yielded an average grain size of 15.86 μm, a yield strength of 712 MPa, and a tensile strength of 803 MPa.

[0127] Example 8 Step 1: Weigh the elements according to the following mass percentages: Fe 48.52%, Cr 16.98%, Ni 31.41%, Al 2.05%, and Ti 1.04%. Prepare alloy powder with a particle size of 15-45 μm and an oxygen content ≤500 ppm using a gas atomization method. The specific preparation steps are as follows.

[0128] 1.1. Raw material pretreatment and purity assurance: Use elemental metals with a purity of ≥99.95% (such as Fe, Cr, Ni). For easily oxidized elements (such as Al, Ti), use high-purity raw materials that are vacuum-packed to avoid the formation of surface oxide films.

[0129] The raw materials are precisely weighed according to the alloy composition, and then placed in an argon-protected electric arc furnace with a vacuum degree ≤10.-4 Pa, gas pressure 0.05MPa, current 280A, melting time 5 minutes per melting; melting times 4 times, pre-melting into master alloy ingots to ensure uniform composition, and then sanding the surface of the ingots with sandpaper to remove the oxide layer.

[0130] 1.2. Preparation of the atomization system: The atomization chamber was evacuated to 5×10 -3 The pressure was maintained at 30 Pa for 30 minutes, then purged with 99.9995% high-purity argon gas; this vacuum-purging cycle was repeated four times until the oxygen partial pressure in the atomization chamber was ≤5×10⁻⁶. -5 Pa.

[0131] 1.3. Alloy smelting: The master alloy ingot is placed in a crucible and melted by medium-frequency induction heating under argon protection. The temperature is raised to 150±10°C above the alloy liquidus line (1530°C). In this embodiment, the temperature is raised to 1690°C and then held for 15 minutes. The total number of melting times is 3. During the process, the alloy liquid is stirred with a graphite rod to ensure uniform composition.

[0132] 1.4. Powder cooling: A secondary cooling zone is set up at the bottom of the atomization chamber, and low-temperature argon gas at -196℃ is introduced to increase the powder cooling rate to 10. 5 K / s, inhibits oxidation on the particle surface and allows the powder to cool to room temperature.

[0133] The powder, cooled to room temperature, was evenly poured onto a vibrating sieve. The vibration frequency of the sieve was set to 40Hz, the ultrasonic power to 60W, and the sieving time to 15 minutes. After sieving, the 15-45μm target powder was gently swept into a clean container and then placed in a vacuum drying oven at 80℃ for 4 hours to remove moisture and impurities, yielding FeCrNiAlTi alloy material powder.

[0134] Step 2: Load the model and set up the printer for printing: Printing is performed using a selective laser melting (SLM) device. Before operating the device, check the focusing of the optical path, the flatness of the powder spreading roller, and the sealing of the argon gas protection path. Preheat the substrate to 180°C. The additive manufacturing method used for this FeCrNiAlTi alloy material powder is selective laser melting (SLM) technology. The processed FeCrNiAlTi alloy material powder is evenly spread on the printing platform to form a thin powder layer. The laser power is set to 170W, the scanning speed to 1800mm / s, the scanning interval to 100μm, and argon gas with a purity of 99.99% is introduced. The laser beam scans and melts the powder layer by layer according to the scanning path generated by the slicing software, causing the powder to accumulate and solidify layer by layer, gradually forming the shape under the protection of argon gas.

[0135] The specific steps are as follows: 2.1. 3D Model Design and Slicing Processing: Based on the structural requirements of the parts, the model was imported into the SLM-specific slicing software using CAD software. The scanning power, scanning time, and scanning spacing were set for printing, and scanning was performed using "bidirectional parallel lines + 67° rotation between layers".

[0136] 2.2. Pretreatment of FeCrNiAlTi alloy powder: The powder was sieved using a sieve inside an argon-protected glove box to remove agglomerated particles and impurities, ensuring that the powder particle size was concentrated between 15-45 μm. The powder was then placed in a vacuum drying oven and dried for 5 hours to remove adsorbed moisture and gases.

[0137] 2.3. Equipment Debugging: The substrate was preheated to 200°C, and 99.999% high-purity argon gas was introduced to replace the air in the printing chamber three times, resulting in a final oxygen content ≤100ppm. Pretreated FeCrNiAlTi powder was then evenly spread onto the substrate to form the first powder layer. The scanning parameters were set as follows: laser power 170W; scanning speed: 1800mm / s; scanning spacing: 100μm. After each layer was scanned, the printing platform descended by one layer thickness, and the powder spreading device spread powder again. This scanning process was repeated to obtain 148 printed layers, with the scanning direction of adjacent layers rotated by 67°.

[0138] 2.4. Post-processing stage: After printing, maintain an argon atmosphere and allow the parts to cool to below 100°C within the printing chamber (to prevent rapid cooling and thermal stress cracking). Open the chamber door and use a special tool to remove the substrate and parts together, removing excess powder for recycling.

[0139] The finished product was wire-cut into rod-shaped tensile samples with dimensions of 30mm*7mm*2mm. Then, a heat treatment experiment was conducted, with the holding temperature set at 580℃ and the holding time at 600 minutes, yielding laser additive manufacturing aging steel.

[0140] The laser additive manufacturing of aged steel samples yielded an average grain size of 8.45 μm, a yield strength of 647 MPa, and a tensile strength of 756 MPa.

[0141] Example 9 Step 1: Weigh the elements according to the following mass percentages: Fe 48.52%, Cr 16.98%, Ni 31.41%, Al 2.05%, and Ti 1.04%. Prepare alloy powder with a particle size of 15-45 μm and an oxygen content ≤500 ppm using a gas atomization method. The specific preparation steps are as follows.

[0142] 1.1. Raw material pretreatment and purity assurance: Use elemental metals with a purity of ≥99.95% (such as Fe, Cr, Ni). For easily oxidized elements (such as Al, Ti), use high-purity raw materials that are vacuum-packed to avoid the formation of surface oxide films.

[0143] The raw materials are precisely weighed according to the alloy composition, and then placed in an argon-protected electric arc furnace with a vacuum degree ≤10. -4 Pa, gas pressure 0.05MPa, current 300A, melting time 4 minutes per melting; melting times 4 times, pre-melting into master alloy ingots to ensure uniform composition, and then sanding the surface of the ingots after pre-melting to remove the oxide layer.

[0144] 1.2. Preparation of the atomization system: The atomization chamber was evacuated to 5×10 -3 The pressure was maintained at 30 Pa for 30 minutes, then purged with 99.9995% high-purity argon gas; this vacuum-purging cycle was repeated four times until the oxygen partial pressure in the atomization chamber was ≤5×10⁻⁶. -5 Pa.

[0145] 1.3. Alloy smelting: The master alloy ingot is placed in a crucible and melted by medium-frequency induction heating under argon protection. The temperature is raised to 150±10°C above the alloy liquidus line (1530°C). In this embodiment, the temperature is raised to 1670°C and then held for 13 minutes. The total number of melting times is 4. During this period, the alloy liquid is stirred with a graphite rod to ensure uniform composition.

[0146] 1.4. Powder cooling: A secondary cooling zone is set up at the bottom of the atomization chamber, and low-temperature argon gas at -196℃ is introduced to increase the powder cooling rate to 10. 5 K / s, inhibits oxidation on the particle surface and allows the powder to cool to room temperature.

[0147] The powder, cooled to room temperature, was evenly poured onto a vibrating sieve. The vibration frequency of the sieve was set to 40Hz, the ultrasonic power to 60W, and the sieving time to 15 minutes. After sieving, the 15-45μm target powder was gently swept into a clean container and then placed in a vacuum drying oven at 80℃ for 4 hours to remove moisture and impurities, yielding FeCrNiAlTi alloy material powder.

[0148] Step 2: Load the model and set up the printer for printing: Printing is performed using a selective laser melting (SLM) device. Before operating the device, check the focusing of the optical path, the flatness of the powder spreading roller, and the sealing of the argon gas protection path. Preheat the substrate to 190°C. The additive manufacturing method used for this FeCrNiAlTi alloy material powder is selective laser melting (SLM) technology. The processed FeCrNiAlTi alloy material powder is evenly spread on the printing platform to form a thin powder layer. The laser power is set to 130W, the scanning speed to 800mm / s, the scanning interval to 90μm, and 99.99% pure argon gas is introduced. The laser beam scans and melts the powder layer by layer according to the scanning path generated by the slicing software, causing the powder to accumulate and solidify layer by layer, gradually forming the shape under the protection of argon gas.

[0149] The specific steps are as follows: 2.1. 3D Model Design and Slicing Processing: Based on the structural requirements of the parts, the model was imported into the SLM-specific slicing software using CAD software. The scanning power, scanning time, and scanning spacing were set for printing, and scanning was performed using "bidirectional parallel lines + 67° rotation between layers".

[0150] 2.2. Pretreatment of FeCrNiAlTi alloy powder: The powder was sieved using a sieve inside an argon-protected glove box to remove agglomerated particles and impurities, ensuring that the powder particle size was concentrated between 15-45 μm. The powder was then placed in a vacuum drying oven and dried for 5 hours to remove adsorbed moisture and gases.

[0151] 2.3. Equipment Debugging: The substrate was preheated to 200°C, and 99.999% high-purity argon gas was introduced to replace the air in the printing chamber three times, resulting in a final oxygen content ≤100ppm. Pretreated FeCrNiAlTi powder was then evenly spread onto the substrate to form the first powder layer. The scanning parameters were set as follows: laser power 130W; scanning speed: 800mm / s; scanning spacing: 90μm. After each layer was scanned, the printing platform descended by one layer thickness, and the powder spreading device spread powder again. This scanning process was repeated to obtain 148 printed layers, with the scanning direction of adjacent layers rotated by 67°.

[0152] 2.4. Post-processing stage: After printing, maintain an argon atmosphere and allow the parts to cool to below 100°C within the printing chamber (to prevent rapid cooling and thermal stress cracking). Open the chamber door and use a special tool to remove the substrate and parts together, removing excess powder for recycling.

[0153] The finished product was wire-cut into rod-shaped tensile samples with dimensions of 30mm*7mm*2mm. Then, a heat treatment experiment was conducted, with the holding temperature set at 580℃ and the holding time at 600 minutes, yielding laser additive manufacturing aging steel.

[0154] The laser additive manufacturing of aged steel samples yielded an average grain size of 9.12 μm, a yield strength of 692 MPa, and a tensile strength of 781 MPa.

[0155] Example 10 Step 1: Weigh the elements according to the following mass percentages: Fe 48.52%, Cr 16.98%, Ni 31.41%, Al 2.05%, and Ti 1.04%. Prepare alloy powder with a particle size of 15-45 μm and an oxygen content ≤500 ppm using a gas atomization method. The specific preparation steps are as follows.

[0156] 1.1. Raw material pretreatment and purity assurance: Use elemental metals with a purity of ≥99.95% (such as Fe, Cr, Ni). For easily oxidized elements (such as Al, Ti), use high-purity raw materials that are vacuum-packed to avoid the formation of surface oxide films.

[0157] The raw materials are precisely weighed according to the alloy composition, and then placed in an argon-protected electric arc furnace with a vacuum degree ≤10. -4 Pa, gas pressure 0.05MPa, current 300A, melting time 4 minutes per melting; melting times 4 times, pre-melting into master alloy ingots to ensure uniform composition, and then sanding the surface of the ingots after pre-melting to remove the oxide layer.

[0158] 1.2. Preparation of the atomization system: The atomization chamber was evacuated to 5×10 -3 The pressure was maintained at 30 Pa for 30 minutes, then purged with 99.9995% high-purity argon gas; this vacuum-purging cycle was repeated four times until the oxygen partial pressure in the atomization chamber was ≤5×10⁻⁶. -5 Pa.

[0159] 1.3. Alloy smelting: The master alloy ingot is placed in a crucible and melted by medium-frequency induction heating under argon protection. The temperature is raised to 150±10°C above the alloy liquidus line (1530°C). In this embodiment, the temperature is raised to 1670°C and then held for 13 minutes. The total number of melting times is 4. During this period, the alloy liquid is stirred with a graphite rod to ensure uniform composition.

[0160] 1.4. Powder cooling: A secondary cooling zone is set up at the bottom of the atomization chamber, and low-temperature argon gas at -196℃ is introduced to increase the powder cooling rate to 10. 5 K / s, inhibits oxidation on the particle surface and allows the powder to cool to room temperature.

[0161] The powder, cooled to room temperature, was evenly poured onto a vibrating sieve. The vibration frequency of the sieve was set to 40Hz, the ultrasonic power to 60W, and the sieving time to 15 minutes. After sieving, the 15-45μm target powder was gently swept into a clean container and then placed in a vacuum drying oven at 80℃ for 4 hours to remove moisture and impurities, yielding FeCrNiAlTi alloy material powder.

[0162] Step 2: Load the model and set up the printer for printing: Printing is performed using a selective laser melting (SLM) device. Before operating the device, check the focusing of the optical path, the flatness of the powder spreading roller, and the sealing of the argon gas protection path. Preheat the substrate to 190°C. The additive manufacturing method used for this FeCrNiAlTi alloy material powder is selective laser melting (SLM) technology. The processed FeCrNiAlTi alloy material powder is evenly spread on the printing platform to form a thin powder layer. The laser power is set to 130W, the scanning speed to 800mm / s, the scanning interval to 90μm, and 99.99% pure argon gas is introduced. The laser beam scans and melts the powder layer by layer according to the scanning path generated by the slicing software, causing the powder to accumulate and solidify layer by layer, gradually forming the shape under the protection of argon gas.

[0163] The specific steps are as follows: 2.1. 3D Model Design and Slicing Processing: Based on the structural requirements of the parts, the model was imported into the SLM-specific slicing software using CAD software. The scanning power, scanning time, and scanning spacing were set for printing, and scanning was performed using "bidirectional parallel lines + 67° rotation between layers".

[0164] 2.2. Pretreatment of FeCrNiAlTi alloy powder: The powder was sieved using a sieve inside an argon-protected glove box to remove agglomerated particles and impurities, ensuring that the powder particle size was concentrated between 15-45 μm. The powder was then placed in a vacuum drying oven and dried for 5 hours to remove adsorbed moisture and gases.

[0165] 2.3. Equipment Debugging: The substrate was preheated to 200°C, and 99.999% high-purity argon gas was introduced to replace the air in the printing chamber three times, resulting in a final oxygen content ≤100ppm. Pretreated FeCrNiAlTi powder was then evenly spread onto the substrate to form the first powder layer. The scanning parameters were set as follows: laser power 130W; scanning speed: 800mm / s; scanning spacing: 90μm. After each layer was scanned, the printing platform descended by one layer thickness, and the powder spreading device spread powder again. This scanning process was repeated to obtain 148 printed layers, with the scanning direction of adjacent layers rotated by 67°.

[0166] 2.4. Post-processing stage: After printing, maintain an argon atmosphere and allow the parts to cool to below 100°C within the printing chamber (to prevent rapid cooling and thermal stress cracking). Open the chamber door and use a special tool to remove the substrate and parts together, removing excess powder for recycling.

[0167] The finished product was wire-cut into rod-shaped tensile samples with dimensions of 30mm*7mm*2mm. Then, a heat treatment experiment was conducted, with the holding temperature set at 580℃ and the holding time at 600 minutes, yielding laser additive manufacturing aging steel.

[0168] The laser additive manufacturing of aged steel samples yielded an average grain size of 9.58 μm, a yield strength of 706 MPa, and a tensile strength of 813 MPa.

[0169] Comparative Example 1 Pure iron (Fe), metallic chromium (Cr), metallic nickel (Ni), aluminum ingots (Al), and sponge titanium (Ti) with a purity ≥99.5% were used. Each element was weighed according to the following mass percentages: Fe 49.06%, Cr 16.28%, Ni 30.82%, Al 2.4%, and Ti 1.44%.

[0170] Remove oxide scale and oil stains from the surface of the raw material by sanding. Dry the raw material at 100℃ for 2 hours to remove moisture. Add the raw material and 0.5g of deoxidizer Al (0.024% of the total raw material mass) to a vacuum induction melting furnace and stir. This will be used to prepare a FeCrNiAlTi alloy with uniform composition, no defects, and meeting performance standards. Pour at 1500℃ for 40 seconds, and continuously purge argon gas into the mold during pouring to prevent secondary oxidation of the melt. Then allow the casting to cool naturally in the mold to below 300℃ before demolding. Then conduct a heat treatment experiment, setting the holding temperature to 580℃ and the holding time to 600 minutes.

[0171] The average grain size is 35μm, the yield strength is 450MPa, and the tensile strength is 650MPa.

[0172] Figure 1 The microstructure of the laser additive manufacturing aged steel prepared in Example 1 shows that the powder is generally spherical, which is a typical characteristic of mainstream powder preparation processes such as gas atomization. This facilitates uniform powder distribution during laser powder bed melting, ensuring powder flowability and sintering density. The particle size of 15μm to 53μm meets the requirements of laser powder bed melting for raw material particle size.

[0173] Figure 2EDS mapping analysis clearly revealed the spatial distribution of five elements (Fe, Cr, Ni, Al, and Ti) within individual powder particles. Each element exhibited a uniform and dispersed distribution within the spherical powder, with no obvious element enrichment or segregation. This verified the compositional uniformity of the laser additive manufacturing of aging steel in Example 1, a crucial prerequisite for ensuring controllable microstructure and properties of SLM-formed parts.

[0174] This invention provides a heat treatment method for preparing age-hardening steel using laser additive manufacturing, which has the following advantages: I. Refining grains to overcome the microstructural bottlenecks of traditional casting. The average grain size of the laser additive manufacturing aged steel prepared in Example 1 was further reduced to 8.43 μm, which is only 24.1% of that of conventional casting.

[0175] The laser additive manufacturing of the aged steel prepared in Example 2 has an average grain size of 13.33 μm, only 38.1% of that in conventional casting. This grain refinement not only reduces size but also improves microstructure uniformity. During additive manufacturing, the layer-by-layer laser deposition creates repeated heating-cooling cycles, suppressing elemental segregation and avoiding the coarse second phase at grain boundaries commonly found in conventional casting. Specifically, heat treatment at 580°C for 600 minutes after additive manufacturing induces the directional precipitation of the B2 phase. This phase, with nanoscale dimensions, is uniformly dispersed in the refined grain matrix, further optimizing the microstructure and laying a core microstructural foundation for subsequent mechanical property enhancement.

[0176] The formula for calculating volume energy density is VED = P / v × h × t; where P: laser power (W); v: scanning speed (mm / s); h: scanning distance (mm); t: powder layer thickness (mm); VED unit: J / mm 3 .

[0177] The volume energy density corresponding to the examples is: Example 1 is 67 J / mm². 3 Example 2 is 67 J / mm 3 Example 3 is 67 J / mm 3 Example 4 is 70 J / mm 3 Example 5 is 54 J / mm 3 Example 6 is 62 J / mm 3 Example 7 is 69 J / mm 3 Example 8 is 31 J / mm 3 Example 9 is 60 J / mm 3 Example 10 is 60 J / mm 3 .

[0178] The embodiments of the present invention can ensure that the bulk energy density is in the range of full melting without overheating, taking into account both density and grain refinement.

[0179] II. Significantly enhances strength, achieving precise strength-tissue matching. The laser additive manufacturing aging steel prepared in Example 1 has a yield strength of 755 MPa, which is 67.8% higher than that of traditional casting; and a tensile strength of 877 MPa, which is 34.9% higher than that of traditional casting.

[0180] The laser additive manufacturing aging steel prepared in Example 2 has a yield strength of 728 MPa, which is 61.8% higher than that of traditional casting; and a tensile strength of 843 MPa, which is 29.7% higher than that of traditional casting.

[0181] Refined grain boundaries significantly hinder dislocation movement, and the rapid solidification of additive manufacturing introduces high-density dislocations and in-situ nano-precipitates. This, combined with the ordered strengthening and coherent strain strengthening resulting from the B2 phase precipitated during heat treatment at 480℃~680℃ for 600min~720min, leads to a synergistic effect of grain refinement, dislocation strengthening, and dispersion strengthening, significantly enhancing the alloy's resistance to plastic deformation. Traditional casting is prone to porosity and pores due to cooling shrinkage (density typically 95%~98%), while additive manufacturing, through layer-by-layer melting-solidification metallurgical bonding, can achieve a density of over 99.5%, reducing the weakening effect of pore-type defects on fracture strength and enabling the alloy to withstand higher loads before fracture.

[0182] Third, while improving strength, performance stability and adjustability are also taken into account. Traditional casting of FeCrNiAlTi alloys suffers from low strength and significant performance fluctuations due to coarse grains and compositional segregation. In contrast, alloys prepared by additive manufacturing exhibit superior performance uniformity. Furthermore, grain size and dislocation density can be precisely controlled through process parameters. Combined with a standardized heat treatment process at 580℃ for 600 minutes to achieve stable precipitation of the B2 phase, this further ensures the consistency of performance across different batches. The combination of additive manufacturing and heat treatment for directional B2 phase precipitation not only solves the structural defects and performance fluctuations inherent in traditional casting but also achieves precise control over the strengthening phase. Ultimately, this upgrades traditional FeCrNiAlTi alloys from medium-strength general-purpose materials to high-strength, high-reliability high-end structural materials, expanding their application scope in key fields such as nuclear industry, aerospace, and high-end equipment manufacturing.

[0183] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0184] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method of heat treatment for a laser additive manufactured age steel, characterized in that, It comprises the following steps: The raw material powders are weighed according to the following mass percentages: Fe 40-50%, Cr 10-18%, Ni 22-32%, Al 2.0-2.5%, and Ti 1.0-1.5%, and the total is 100%; The weighed raw material powders are pre-melted to obtain a master alloy ingot with uniform composition and density; and the master alloy ingot is used to prepare an alloy powder by an aerosol method; The alloy powder is processed by a laser selective melting method in an inert gas protection environment to obtain an FeCrNiAlTi alloy material, and then the FeCrNiAlTi alloy material is heat treated to obtain a laser additive manufacturing aging steel, and the laser additive manufacturing aging steel has a B2 phase.

2. A method of heat treatment of a laser additive manufactured age steel according to claim 1, characterized in that, The heat treatment condition is 480-680℃, and the holding time is 600-720min.

3. The method of claim 1, wherein the method further comprises: When the laser selective melting method is used for processing, the laser power is 110-300W, and the scanning speed is 800-1800mm / s.

4. The method of claim 1, wherein the method further comprises: When the laser selective melting method is used for processing, the scanning interval is 80-100μm.

5. The method of claim 1, wherein the method further comprises: The aerosol method processing step is: The master alloy ingot is melted in an inert gas atmosphere to obtain a molten melt, and the molten melt is atomized to obtain an alloy powder.

6. The method of claim 5, wherein the method further comprises: The melting temperature is 1670-1690℃, the melting time is 10-15min each time, and the melting number is 3-4 times.

7. The method of claim 5, wherein the method further comprises: The pre-melting current is 250-300A, the melting time is 4-6min each time, and the melting number is 4-5 times.

8. The method of claim 1, wherein the method further comprises: Before the laser selective melting method is used for processing, the substrate is preheated to 180-200℃. 9.A laser additive manufacturing aging steel prepared by the heat treatment preparation method of claims 1-8. 10.Use of the laser additive manufacturing aging steel of claim 9 in the preparation of alloy parts and part coatings.

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