A method for eliminating residual stress in additively manufactured nickel-based high-temperature alloys

Abstract

The present invention relates to a method for eliminating residual stress in additively manufactured nickel-based high-temperature alloys, and relates to the technical field of additively manufactured materials. The main technical solution adopted is: stress elimination treatment is performed by applying continuous pulse current treatment to the additively manufactured nickel-based high-temperature alloy to eliminate at least part of the residual stress in the additively manufactured nickel-based high-temperature alloy, thereby obtaining the additively manufactured nickel-based high-temperature alloy after stress elimination treatment. The present invention can effectively reduce the residual stress in the additively manufactured nickel-based high-temperature alloy. The method of the present invention does not change the internal organizational state of the original alloy. At the same time, the method of the present invention has a low processing temperature, a short processing time, is more efficient and energy-saving, and meets the current requirements of green and sustainable development of industry.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing materials, and in particular to a method for eliminating residual stress in additively manufactured nickel-based high-temperature alloys. Background Art

[0002] Additive Manufacturing (AM) is a digital manufacturing method that is conducive to the realization of automated, intelligent and networked manufacturing. Compared with traditional manufacturing methods, the additive manufacturing process is simple and efficient, with high material utilization rate, and has been widely used in industrial fields such as automobiles, aerospace, energy and medical equipment. Metal additive manufacturing technology can be divided into direct energy deposition (DED) and powder bed fusion (PBF). Among them, DED includes laser metal deposition (LMD) and wire arc additive manufacturing (WAAM). Among them, PBF includes electron beam selective melting (EBSM) and laser selective melting (SLM).

[0003] The unique thermal cycle characteristics of metal additive manufacturing are: (1) high energy intensity, steep temperature gradients, and rapid heating rates; (2) small melt pool volume, rapid cooling rates, and rapid solidification rates; and (3) melt reflow, which involves simultaneously melting the top powder layer and remelting the previously solidified bottom layer. The residual stress caused by the unique thermal cycle in additive manufacturing is a key issue in the manufacture of metal parts. Large residual stresses can cause part deformation, thereby reducing the dimensional accuracy of the parts. In addition, they can easily cause parts to crack during long-term service, greatly reducing the ultimate service life of the parts. Therefore, additive manufacturing technology still faces huge challenges in part quality control.

[0004] At present, the research on eliminating residual stress in additively manufactured alloys mainly focuses on two methods: adjusting printing process parameters and traditional heat treatment. The effect of eliminating residual stress by adjusting the additive manufacturing printing process parameters is very limited, and it will also bring about significant changes in the mechanical properties of the parts, affecting their strength and plasticity. Another method is traditional heat treatment or hot isostatic pressing. The existing technology proposes a method for reducing residual stress in additively manufactured high-temperature alloys based on hot isostatic pressing. Hot isostatic pressing is performed on an additively manufactured high-temperature alloy. Although this method effectively eliminates the residual stress inside the sample, the processing temperature of this method is high, the processing time is long, and the internal structure of the original sample is changed.

[0005] In summary, in response to the bottleneck problems encountered in existing technologies, it is urgent to develop a new method to eliminate residual stress in additively manufactured nickel-based high-temperature alloys, which can effectively reduce the residual stress in additively manufactured nickel-based high-temperature alloys and play an important role in promoting the industrial application of additively manufactured nickel-based high-temperature alloys. Summary of the Invention

[0006] In view of this, the present invention provides a method for eliminating residual stress in additively manufactured nickel-based high-temperature alloys, the main purpose of which is to effectively reduce the residual stress in additively manufactured nickel-based high-temperature alloys.

[0007] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0008] On the one hand, an embodiment of the present invention provides a method for eliminating residual stress in an additively manufactured nickel-based high-temperature alloy, wherein stress elimination treatment is performed by applying continuous pulse current treatment to the additively manufactured nickel-based high-temperature alloy to eliminate at least part of the residual stress in the additively manufactured nickel-based high-temperature alloy, thereby obtaining an additively manufactured nickel-based high-temperature alloy after stress elimination treatment.

[0009] Preferably, the chemical composition of the additively manufactured nickel-based high-temperature alloy is as follows, in terms of weight percentage: Fe: 1-35wt%, Cr: 2-35wt%, Mo: 0-10wt%, Al: 0.1-5wt%, Ti: 0-5wt%, Nb: 2-10wt%, Ta: 0-5wt%, W: 0.5-5wt%, Co: 1-20wt%, Zr: 0-1wt%, Hf: 0-1wt%, C: 0-0.5wt%, B: 0-0.05wt%, Si: 0-0.05wt%, Ni: balance.

[0010] Preferably, the additively manufactured nickel-based high-temperature alloy is a laser additively manufactured deposited nickel-based high-temperature alloy. Preferably, the additively manufactured nickel-based high-temperature alloy is a laser direct energy deposition additively manufactured deposited nickel-based high-temperature alloy.

[0011] Preferably, the parameters of the continuous pulse current treatment are as follows: the continuous pulse current density is 10-400A / mm 2 , the continuous pulse current width is 1us-5ms, the continuous pulse current frequency is 1-50Hz, the duty cycle is 10-99%, the temperature of the continuous pulse current treatment is 900-1100℃, and the time of the continuous pulse current treatment is 1-20min.

[0012] Preferably, the parameters of the continuous pulse current treatment are as follows: the continuous pulse current density is 200-300A / mm 2, the continuous pulse current width is 0.05-1ms, the continuous pulse current frequency is 10-30Hz, the duty cycle is 20-80%, the temperature of the continuous pulse current treatment is 1000℃±2℃, and the time of the continuous pulse current treatment is 6min±2min.

[0013] Preferably, the dislocation density in the laser additively manufactured deposited nickel-based high-temperature alloy is 8×10 14 m 2 -10×10 14 m 2 ; and / or the dislocation density in the additively manufactured nickel-based high-temperature alloy after the stress relief treatment is 1×10 13 m 2 -2×10 14 m 2 .

[0014] Preferably, the additively manufactured nickel-based high-temperature alloy is an arc additively manufactured deposited nickel-based high-temperature alloy.

[0015] Preferably, the parameters of the continuous pulse current treatment are as follows: the continuous pulse current density is 300-400A / mm 2 , the continuous pulse current width is 0.2-0.8ms, the continuous pulse current frequency is 30-50Hz, the duty cycle is 30-60%, the temperature of the continuous pulse current treatment is 1100℃±2℃, and the time of the continuous pulse current treatment is 10min±2min.

[0016] Preferably, the GND density in the arc additively manufactured deposited nickel-based high-temperature alloy is 8×10 14 m 2 -10×10 14 m 2 ; and the GND density of the additively manufactured nickel-based high-temperature alloy after the stress relief treatment is 1×10 13 m 2 -2×10 14 m 2 .

[0017] Preferably, the method for eliminating residual stress in additively manufactured nickel-based high-temperature alloys comprises the following steps:

[0018] Step 1) processing the additively manufactured nickel-based high-temperature alloy into a workpiece for continuous pulse current processing;

[0019] Step 2), connecting the workpiece to a pulse power supply, turning on the pulse power supply, and applying a continuous pulse current treatment to the workpiece;

[0020] Step 3), cooling the workpiece after continuous pulse current treatment to obtain a treated additively manufactured nickel-based high-temperature alloy;

[0021] Preferably, in step 1), the additively manufactured nickel-based high-temperature alloy is cut, polished, and cleaned to obtain a workpiece of a set size.

[0022] Compared with the prior art, the method of eliminating residual stress in additively manufactured nickel-based high-temperature alloys of the present invention has at least the following beneficial effects:

[0023] An embodiment of the present invention provides a method for eliminating residual stress in additively manufactured nickel-based high-temperature alloys, which eliminates at least part of the residual stress in the additively manufactured nickel-based high-temperature alloy by applying a continuous pulse current treatment to the additively manufactured nickel-based high-temperature alloy, thereby obtaining an additively manufactured nickel-based high-temperature alloy after stress elimination. Here, the present invention applies a continuous pulse current to the additively manufactured nickel-based high-temperature alloy, so that the combination of electrical effect (electron wind force) and thermal effect (Joule heat) drives the movement of dislocations in the alloy, wherein the electron wind force drives electrons to continuously impact the dislocations to increase the movement and speed of dislocation slip and climbing; Joule heat provides a driving force for dislocation migration, increases the vibration frequency of dislocations, and provides energy for the accelerated movement of dislocations; the above two effects ultimately lead to the rearrangement and annihilation of dislocations, reduce the dislocation density, and effectively eliminate the residual stress in the additively manufactured nickel-based high-temperature alloy.

[0024] Furthermore, embodiments of the present invention provide a method for eliminating residual stress in additively manufactured nickel-based superalloys. When applying a continuous pulse current treatment to the additively manufactured nickel-based superalloy, the selection of pulse current parameters is crucial. By selecting appropriate continuous pulse current treatment parameters, residual stress in the alloy can be eliminated to a significant extent while maintaining the original alloy microstructure. Improper selection of pulse current parameters can lead to inadequate elimination of residual stress in the alloy or alteration of the alloy microstructure.

[0025] In summary, compared with traditional heat treatment processes, the method provided by the embodiments of the present invention for eliminating residual stress in additively manufactured nickel-based superalloys does not alter the original alloy's internal microstructure. Furthermore, the method of the present invention offers low processing temperatures and short processing times, resulting in greater efficiency and energy savings, meeting current requirements for green and sustainable industrial development. Therefore, the present invention provides a new method for eliminating residual stress in nickel-based superalloys manufactured using additive methods such as laser and arc processes.

[0026] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a comparison chart of the GND density of laser additive manufacturing samples that have not been treated with continuous pulse current and samples after stress removal treatment in different embodiments and comparative examples.

[0028] Figure 2 These are the EBSD results of the laser additively manufactured sample without continuous pulse current treatment; (a) is the IPF map, and (b) is the GND density map.

[0029] Figure 3 These are the EBSD results of the laser additively manufactured sample after continuous pulse current treatment in Example 1; among them, (a) is the IPF map, and (b) is the GND density map.

[0030] Figure 4 These are the EBSD results of the laser additively manufactured sample after continuous pulse current treatment in Example 2; among them, (a) is the IPF map, and (b) is the GND density map.

[0031] Figure 5 These are the EBSD results of the laser additive manufacturing sample after continuous pulse current treatment in Example 3; among them, (a) is the IPF map, and (b) is the GND density map.

[0032] Figure 6 This is a comparison diagram of the GND density of the arc additively manufactured sample that has not been treated with continuous pulse current and the arc additively manufactured sample that has been treated with stress removal in the embodiment.

[0033] Figure 7 These are the EBSD results of the arc additive manufacturing sample without continuous pulse current treatment; (a) is the IPF map, and (b) is the GND density map.

[0034] Figure 8 These are the EBSD results of the arc additive manufacturing sample after continuous pulse current treatment in Example 4; among them, (a) is the IPF map, and (b) is the GND density map.

[0035] Figure 9 These are the EBSD results of the laser additive manufacturing sample after traditional heat treatment in Comparative Example 1; among them, (a) is the IPF map, and (b) is the GND density map.

[0036] Figure 10 These are the EBSD results of the laser additive manufacturing sample after traditional heat treatment in Comparative Example 2; among them, (a) is the IPF map, and (b) is the GND density map.

[0037] Figure 11These are the EBSD results of the laser additive manufacturing sample after continuous pulse current treatment in Comparative Example 3; among them, (a) is the IPF map, and (b) is the GND density map. DETAILED DESCRIPTION

[0038] To further illustrate the technical means and effects employed by the present invention to achieve its intended objectives, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention is provided in conjunction with the accompanying drawings and preferred embodiments. In the following description, different references to "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0039] To overcome the difficulties of the prior art, the present invention provides a method for eliminating residual stress in additively manufactured nickel-based superalloys. By applying a continuous pulse current to the additively manufactured nickel-based superalloy, the method can quickly reduce or eliminate the residual stress within the sample. The specific solution of the present invention is as follows:

[0040] An embodiment of the present invention provides a method for eliminating residual stress in additively manufactured nickel-based high-temperature alloys, comprising the following steps:

[0041] Step 1) Processing the additively manufactured nickel-based high-temperature alloy into a workpiece for continuous pulse current processing.

[0042] Preferably, the additively manufactured nickel-based high-temperature alloy is cut, polished, and cleaned to obtain a workpiece of a set size.

[0043] Step 2) Connect the workpiece to a pulse power supply, turn on the pulse power supply, and apply continuous pulse current treatment to the workpiece.

[0044] Step 3), cooling the workpiece after continuous pulse current treatment to obtain the treated additively manufactured nickel-based high-temperature alloy.

[0045] Here, regarding the above-mentioned solution of the present invention, the chemical composition of the nickel-based high-temperature alloy for additive manufacturing is as follows, calculated in percentage by weight:

[0046] Fe: 1-35wt%, Cr: 2-35wt%, Mo: 0-10wt%, Al: 0.1-5wt%, Ti: 0-5wt%, Nb: 2-10wt%, Ta: 0-5wt%, W: 0.5-5wt%, Co: 1-20wt%, Zr: 0-1wt%, Hf: 0-1wt%, C: 0-0.5wt%, B: 0-0.05wt%, Si: 0-0.05wt%, Ni: balance

[0047] Here, regarding the above-mentioned solution of the present invention, the additively manufactured high-temperature nickel-based superalloy is a laser additively manufactured deposited nickel-based superalloy or an arc additively manufactured deposited nickel-based superalloy.

[0048] Wherein, the additive manufacturing of high-temperature nickel-based superalloy is laser additive manufacturing of deposited nickel-based superalloy, and the parameters of the continuous pulse current treatment are as follows:

[0049] Continuous pulse current density is 10-400A / mm 2 , the continuous pulse current width is 1us-5ms, the continuous pulse current frequency is 1-50Hz, the duty cycle is 10-99%, the temperature of the continuous pulse current treatment is 900-1100℃, and the time of the continuous pulse current treatment is 1-20min.

[0050] Preferably, the continuous pulse current density is 200-300A / mm 2 , the continuous pulse current width is 0.05-1ms, the continuous pulse current frequency is 10-30Hz, the duty cycle is 20-80%, the temperature of the continuous pulse current treatment is 1000℃±2℃, and the time of the continuous pulse current treatment is 6min±2min.

[0051] Wherein, the additively manufactured high-temperature nickel-based superalloy is an arc additively manufactured deposited nickel-based superalloy, and the parameters of the continuous pulse current treatment are as follows:

[0052] Continuous pulse current density is 300-400A / mm 2 , the continuous pulse current width is 0.2-0.8ms, the continuous pulse current frequency is 30-50Hz, the duty cycle is 30-60%, the temperature of the continuous pulse current treatment is 1100℃±2℃, and the time of the continuous pulse current treatment is 10min±2min.

[0053] In addition, the above-mentioned solution of the present invention needs to be explained as follows:

[0054] 1) This invention applies a continuous pulsed current to the additively manufactured nickel-based superalloy, promoting dislocation motion through a combination of electrical effects (electron wind force) and thermal effects (Joule heating). The electron wind force propels electrons to continuously impact dislocations, increasing the movement and speed of dislocation slip and climb. Joule heating provides the driving force for dislocation migration, increasing the vibration frequency of dislocations and providing energy for their accelerated motion. This ultimately leads to the rearrangement and annihilation of dislocations, reducing dislocation density and effectively eliminating residual stress in the additively manufactured nickel-based superalloy.

[0055] 2) The present invention applies a continuous pulse current treatment to the additively manufactured nickel-based superalloy, effectively eliminating residual stress in the alloy at a relatively low temperature. Because the continuous pulse current treatment lasts for a relatively short time, the microstructure of the original alloy remains unchanged.

[0056] In summary, compared with traditional solution heat treatment technology, the present invention utilizes continuous pulse current treatment technology to effectively reduce or eliminate residual stress in additively manufactured nickel-based high-temperature alloys at lower temperatures and in shorter times, and has many advantages such as high efficiency, energy saving and environmental protection.

[0057] The present invention is further described below by means of specific experimental examples:

[0058] In the following examples and comparative examples, laser additive manufacturing samples were printed using a coaxial powder feeding device, and the alloy powder used for printing was prepared by a plasma rotating electrode (PREP) method, wherein the printing process parameters were: laser power of 900w; laser scanning speed of 8mm / s; powder feeding amount of 7g / min, and Z-axis lifting height of 0.7mm.

[0059] The arc additive manufacturing sample was printed by an ABB industrial robot. The wire diameter used for printing was 1.0 mm. The printing process parameters were as follows: wire feed speed of 7 m / min, printing speed of 5 mm / s, airflow protection of 25 L / min, and Z-axis lifting height of 3 mm.

[0060] It should be noted here that the solution of the present invention is mainly proposed for additive manufacturing of nickel-based high-temperature alloys to eliminate residual stress in the alloy. It is not limited to the above-mentioned printing process parameters. As long as it is an additively manufactured nickel-based high-temperature alloy with residual stress, the solution of the present invention can be used for processing.

[0061] In addition, the temperature of the laser additively manufactured nickel-based high-temperature alloy is recorded in real time by an infrared thermometer, and the temperature rise caused by the Joule heating effect of the continuous pulse current is considered to be uniform on the cross section.

[0062] In addition, the compositions of the nickel-based high-temperature alloys manufactured by laser additive manufacturing and arc additive manufacturing in the following embodiments and comparative examples are shown in Table 1. At the same time, in order to intuitively demonstrate the superiority of the continuous pulse current treatment of the present invention, the alloys with the compositions shown in Table 1 were subjected to traditional solution treatment in a box-type resistance furnace for comparison and analysis of the advantages of the continuous pulse current treatment method.

[0063] In addition, the residual stresses in the nickel-based high-temperature alloys produced by laser additive manufacturing and arc additive manufacturing in the following examples and comparative examples were observed and analyzed using EBSD technology, and the changes in the density of geometrically required dislocations (GNDs) were used to approximately reflect the level of residual stress in the samples.

[0064] Table 1 shows the alloy composition (wt%) used in the examples of the present invention.

[0065] element Al Ti Nb W Mo Cr Co Fe C Ni wt% 1.5 0.9 5.4 1.1 2.5 18.1 9.2 9.5 0.02 margin

[0066] Example 1

[0067] In this embodiment, a stress relief treatment is performed by subjecting a laser additively manufactured nickel-based high-temperature alloy to continuous pulse current treatment to eliminate at least a portion of the residual stress in the additively manufactured nickel-based high-temperature alloy. The main steps are as follows:

[0068] 1) Laser additively manufactured nickel-based high-temperature alloys were processed into workpiece specimens for continuous pulsed current processing.

[0069] Strip-shaped workpiece specimens were cut from the deposited samples of nickel-based high-temperature alloy manufactured by laser additive manufacturing. The surfaces were polished in sequence with 400-mesh, 800-mesh, 1200-mesh, and 2000-mesh sandpaper to eliminate wire cutting marks while ensuring that there were no obvious macroscopic defects, so as to ensure good contact between the workpiece specimen and the electrode.

[0070] 2) Connect the sample to the pulse power supply, turn on the pulse power supply, and apply continuous pulse current treatment to the workpiece sample.

[0071] Fix the workpiece sample with a fixture to the output end of the power supply (connect the two poles of the pulse power supply to the two ends of the sample to form a loop).

[0072] The power supply is turned on to apply continuous pulse current to the laser additively manufactured nickel-based high-temperature alloy workpiece, wherein the continuous pulse current density is 280A / mm 2 The continuous pulse current width is 0.5ms; the continuous pulse current frequency is 28Hz; the duty cycle is 20%. The continuous pulse current treatment is carried out at 1000℃ for 5 minutes.

[0073] The central part of the sample after continuous pulse current treatment in this embodiment was taken and the residual stress relief and grain morphology in the sample were observed using EBSD characterization technology, as shown in FIG. Figure 3 In addition, the EBSD results of the sample without continuous pulse current treatment are shown in Figure 2 The GND density comparison of the laser additive manufacturing sample without continuous pulse current treatment, the sample obtained in the embodiment and the comparative example is shown in FIG. Figure 1 It is obvious that the GND density (9.51×10 14 m 2 ) is higher, which means that there is a higher residual stress. The GND density (1.98×10 14 m 2) is significantly reduced, which means that the residual stress in the sample has been effectively eliminated. At the same time, the grain orientation, grain size and grain morphology of the sample remain basically unchanged after continuous pulse current treatment.

[0074] Example 2

[0075] In this embodiment, a stress relief treatment is performed by subjecting a laser additively manufactured nickel-based high-temperature alloy to continuous pulse current treatment to eliminate at least a portion of the residual stress in the additively manufactured nickel-based high-temperature alloy. The main steps are as follows:

[0076] 1) Laser additively manufactured nickel-based high-temperature alloys were processed into workpiece specimens for continuous pulsed current processing.

[0077] Strip-shaped workpiece specimens were cut from the deposited samples of nickel-based high-temperature alloy manufactured by laser additive manufacturing. The surfaces were polished in sequence with 400-mesh, 800-mesh, 1200-mesh, and 2000-mesh sandpaper to eliminate wire cutting marks while ensuring that there were no obvious macroscopic defects, so as to ensure good contact between the workpiece specimen and the electrode.

[0078] 2) Connect the sample to the pulse power supply, turn on the pulse power supply, and apply continuous pulse current treatment to the workpiece sample.

[0079] Fix the workpiece sample with a fixture to the output end of the power supply (connect the two poles of the pulse power supply to the two ends of the sample to form a loop).

[0080] The power supply is turned on to apply continuous pulse current to the laser additively manufactured nickel-based high-temperature alloy workpiece, wherein the continuous pulse current density is 280A / mm 2 The continuous pulse current width is 0.5ms; the continuous pulse current frequency is 25Hz; the duty cycle is 20%. The continuous pulse current treatment is carried out at 1000℃ for 6min.

[0081] The central part of the sample after continuous pulse current treatment in this embodiment was taken and the residual stress relief and grain morphology were observed using EBSD characterization technology. Figure 4 shown.

[0082] It is obvious that the sample after continuous pulse current treatment in this embodiment has a lower GND density (1.95×10 14 m 2 ), indicating that residual stress in the sample is low. Compared to the as-deposited sample, the residual stress in the sample treated with continuous pulse current is effectively eliminated. Furthermore, the grain orientation, grain size, and grain morphology of the sample remain largely unchanged after treatment with continuous pulse current.

[0083] Example 3

[0084] In this embodiment, a stress relief treatment is performed by subjecting a laser additively manufactured nickel-based high-temperature alloy to continuous pulse current treatment to eliminate at least a portion of the residual stress in the additively manufactured nickel-based high-temperature alloy. The main steps are as follows:

[0085] 1) Laser additively manufactured nickel-based high-temperature alloys were processed into workpiece specimens for continuous pulsed current processing.

[0086] Strip-shaped workpiece specimens were cut from the deposited samples of nickel-based high-temperature alloy manufactured by laser additive manufacturing. The surfaces were polished in sequence with 400-mesh, 800-mesh, 1200-mesh, and 2000-mesh sandpaper to eliminate wire cutting marks while ensuring that there were no obvious macroscopic defects, so as to ensure good contact between the workpiece specimen and the electrode.

[0087] 2) Connect the sample to the pulse power supply, turn on the pulse power supply, and apply continuous pulse current treatment to the workpiece sample.

[0088] Fix the workpiece sample with a fixture to the output end of the power supply (connect the two poles of the pulse power supply to the two ends of the sample to form a loop).

[0089] Among them, the power is turned on to apply continuous pulse current treatment to the laser additively manufactured nickel-based high-temperature alloy workpiece, and the continuous pulse current density is 180A / mm 2 The continuous pulse current width is 0.8ms; the continuous pulse current frequency is 10Hz; the duty cycle is 50%. The continuous pulse current treatment is carried out at 900℃ for 5 minutes.

[0090] The central part of the sample after continuous pulse current treatment in this embodiment was taken and the residual stress relief and grain morphology were observed using EBSD characterization technology. Figure 5 shown.

[0091] It is obvious that the dislocation density in the sample after continuous pulse current treatment is reduced compared with the as-deposited sample. However, the sample still has a high GND density (5.68×10 14 m 2 ), which means that the residual stress in the sample is still high. This shows that without selecting the optimal pulse current parameters for treatment, the residual stress in the sample is difficult to be effectively eliminated.

[0092] Example 4

[0093] In this embodiment, a stress relief treatment is performed on the arc additively manufactured nickel-based high-temperature alloy by subjecting it to continuous pulse current treatment to eliminate at least part of the residual stress in the additively manufactured nickel-based high-temperature alloy. The main steps are as follows:

[0094] 1) Arc additively manufactured nickel-based high-temperature alloys were processed into workpiece specimens for continuous pulse current processing.

[0095] Strip-shaped workpiece specimens were cut from the deposited samples of nickel-based high-temperature alloys produced by arc additive manufacturing. The surfaces were polished in sequence with 400-mesh, 800-mesh, 1200-mesh, and 2000-mesh sandpaper to eliminate wire cutting marks while ensuring that there were no obvious macroscopic defects, thereby ensuring good contact between the workpiece specimen and the electrode.

[0096] 2) Connect the sample to the pulse power supply, turn on the pulse power supply, and apply continuous pulse current treatment to the workpiece sample.

[0097] Fix the workpiece sample with a fixture to the output end of the power supply (connect the two poles of the pulse power supply to the two ends of the sample to form a loop).

[0098] The power supply is turned on to apply continuous pulse current to the laser additively manufactured nickel-based high-temperature alloy workpiece, wherein the continuous pulse current density is 350A / mm 2 The continuous pulse current width is 0.6ms; the continuous pulse current frequency is 40Hz; the duty cycle is 50%. The continuous pulse current treatment is carried out at 1100℃ for 10 minutes.

[0099] The central part of the sample after continuous pulse current treatment in this embodiment was taken and the residual stress relief and grain morphology in the sample were observed using EBSD characterization technology, as shown in FIG. Figure 8 In addition, the EBSD results of the sample without continuous pulse current treatment are shown in Figure 7 The GND density comparison of the sample without continuous pulse current treatment and the sample obtained in the embodiment is shown in FIG. Figure 6 It is obvious that the GND density (8.31×10 14 m 2 ) is higher, which means that there is a higher residual stress. The GND density (1.52×10 14 m 2 ) is significantly reduced, which means that the residual stress in the sample has been effectively eliminated. At the same time, the grain orientation, grain size and grain morphology of the sample remain basically unchanged after continuous pulse current treatment.

[0100] Comparative Example 1

[0101] Comparative Example 1: A laser additively manufactured nickel-based high-temperature alloy workpiece was subjected to conventional heat treatment, specifically as follows: heating at 1000° C. for 30 minutes for conventional heat treatment.

[0102] EBSD characterization technology was used to observe the residual stress relief and grain morphology of the samples after traditional heat treatment, such as Figure 9 shown.

[0103] It was found that after the laser additive manufacturing nickel-based high-temperature alloy of Example 1 was heated at 1000℃ for 50min for traditional heat treatment, the sample still had a high GND density (5.15×10 14 m 2 ), the elimination effect is significantly different from that of the sample treated with continuous pulse current at 1000°C for 5 minutes as described in the above embodiment. It can be seen that traditional heat treatment at low temperature and for a short time cannot effectively eliminate residual stress in the sample.

[0104] Comparative Example 2

[0105] Comparative Example 2: The laser additively manufactured nickel-based high-temperature alloy workpiece was subjected to traditional solution treatment, specifically as follows: heating at 1150° C. for 60 minutes for traditional heat treatment.

[0106] EBSD characterization technology was used to observe the residual stress relief and grain morphology of the samples after traditional heat treatment, such as Figure 10 shown.

[0107] It was found that after the laser additive manufacturing nickel-based high-temperature alloy of Example 2 was heated at 1150°C for 60 minutes for traditional heat treatment, the GND density in the sample was significantly reduced (1.48×10 14 m 2 ), indicating that residual stress in the sample was substantially eliminated, achieving the same effect as that achieved by the continuous pulse current treatment described in the previous embodiment. However, the grain size of the sample in Comparative Example 2, after conventional heat treatment, had significantly increased. This suggests that continuous pulse current treatment can maintain the original alloy structure while reducing treatment temperature and time.

[0108] Comparative Example 3

[0109] Comparative Example 3: A stress relief treatment is performed on the laser additively manufactured nickel-based high-temperature alloy by subjecting it to continuous pulse current treatment to eliminate at least part of the residual stress in the additively manufactured nickel-based high-temperature alloy. The main steps are as follows:

[0110] 1) Laser additively manufactured nickel-based high-temperature alloys were processed into workpiece specimens for continuous pulsed current processing.

[0111] Strip-shaped workpiece specimens were cut from the deposited samples of nickel-based high-temperature alloy manufactured by laser additive manufacturing. The surfaces were polished in sequence with 400-mesh, 800-mesh, 1200-mesh, and 2000-mesh sandpaper to eliminate wire cutting marks while ensuring that there were no obvious macroscopic defects, so as to ensure good contact between the workpiece specimen and the electrode.

[0112] 2) Connect the sample to the pulse power supply, turn on the pulse power supply, and apply continuous pulse current treatment to the workpiece sample.

[0113] Fix the workpiece sample with a fixture to the output end of the power supply (connect the two poles of the pulse power supply to the two ends of the sample to form a loop).

[0114] The power supply is turned on to apply continuous pulse current to the laser additively manufactured nickel-based high-temperature alloy workpiece, wherein the continuous pulse current density is 9A / mm 2 The continuous pulse current width is 0.8ms; the continuous pulse current frequency is 60Hz; the duty cycle is 9%. The continuous pulse current treatment is carried out at 100℃ for 6 minutes.

[0115] The central part of the pulse current treated sample of Comparative Example 3 was taken and the residual stress relief and grain morphology of the sample after pulse treatment were observed using EBSD characterization technology. Figure 11 shown.

[0116] The results show that: (1) the sample of comparative example 3 after continuous pulse current treatment still has a high GND density (8.66×10 14 m 2 ), which means that the residual stress in the sample is still high. (2) Compared with the deposited sample, the grain orientation, grain size and grain morphology of the sample after continuous pulse current treatment have not changed significantly, and the residual stress has not been effectively eliminated. This is mainly due to the low density of pulse current treatment, which leads to low treatment temperature. The relatively small electron wind force makes it difficult to promote dislocation movement and annihilation, so the residual stress elimination effect of the sample is not significant. Compared with the embodiment, when the parameters of continuous pulse current treatment are not selected reasonably, the ideal effect of residual stress elimination cannot be achieved.

[0117] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiment based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for eliminating residual stress in additively manufactured nickel-based high-temperature alloys, characterized in that: performing stress relief treatment on the additively manufactured nickel-based high-temperature alloy by applying a continuous pulse current treatment to eliminate at least a portion of residual stress in the additively manufactured nickel-based high-temperature alloy, thereby obtaining the additively manufactured nickel-based high-temperature alloy after stress relief treatment; Wherein, when the additively manufactured nickel-based high-temperature alloy is a laser additively manufactured deposited nickel-based high-temperature alloy, the parameters of the continuous pulse current treatment are as follows: the continuous pulse current density is 200-300A / mm 2 , the continuous pulse current width is 0.05-1ms, the continuous pulse current frequency is 10-30Hz, the duty cycle is 20-80%, the temperature of the continuous pulse current treatment is 1000℃±2℃, and the time of the continuous pulse current treatment is 6min±2min; Wherein, when the additively manufactured nickel-based high-temperature alloy is an arc additively manufactured deposited nickel-based high-temperature alloy, the parameters of the continuous pulse current treatment are as follows: Continuous pulse current density is 300-400A / mm 2 , the continuous pulse current width is 0.2-0.8ms, the continuous pulse current frequency is 30-50Hz, the duty cycle is 30-60%, the temperature of the continuous pulse current treatment is 1100℃±2℃, and the time of the continuous pulse current treatment is 10min±2min.

2. The method for eliminating residual stress in additively manufactured nickel-based high-temperature alloy according to claim 1, characterized in that: The chemical composition of the additively manufactured nickel-based high-temperature alloy is as follows, in terms of weight percentage: Fe: 1-35wt%, Cr: 2-35wt%, Mo: 0-10wt%, Al: 0.1-5wt%, Ti: 0-5wt%, Nb: 2-10wt%, Ta: 0-5wt%, W: 0.5-5wt%, Co: 1-20wt%, Zr: 0-1wt%, Hf: 0-1wt%, C: 0-0.5wt%, B: 0-0.05wt%, Si: 0-0.05wt%, Ni: balance 3. The method for eliminating residual stress in additively manufactured nickel-based high-temperature alloy according to claim 2, characterized in that: The laser additive manufacturing deposited nickel-based high-temperature alloy is a laser direct energy deposition additive manufacturing deposited nickel-based high-temperature alloy.

4. The method for eliminating residual stress in additively manufactured nickel-based high-temperature alloy according to claim 1, characterized in that: The GND density in the laser additively manufactured deposited nickel-based high-temperature alloy is 8×10 14 m 2 -10×10 14 m 2 and / or The GND density in the laser additively manufactured deposited nickel-based high-temperature alloy after the stress relief treatment is 1×10 13 m 2 -2×10 14 m 2 .

5. The method for eliminating residual stress in additively manufactured nickel-based superalloys according to claim 1, wherein the GND density in the arc additively manufactured deposited nickel-based superalloy is 8×10 14 m 2 -10×10 14 m 2 and / or The GND density in the arc additively manufactured deposited nickel-based high-temperature alloy after the stress relief treatment is 1×10 13 m 2 -2×10 14 m 2 .

6. The method for eliminating residual stress in additively manufactured nickel-based high-temperature alloy according to claim 1, characterized in that: The method for eliminating residual stress in additively manufactured nickel-based high-temperature alloys comprises the following steps: Step 1), processing the additively manufactured nickel-based high-temperature alloy into a workpiece for continuous pulse current processing; Step 2), connecting the workpiece to a pulse power supply, turning on the pulse power supply, and applying a continuous pulse current to the workpiece; In step 3, the workpiece treated with the continuous pulse current is cooled to obtain the treated additively manufactured nickel-based high-temperature alloy.

7. The method for eliminating residual stress in additively manufactured nickel-based high-temperature alloy according to claim 6, characterized in that: In the step 1), the additively manufactured nickel-based high-temperature alloy is cut, polished, and cleaned to obtain a workpiece of a set size.

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