Component design method of precipitation strengthening type nickel-based alloy capable of resisting laser 3D printing forming cracking

Abstract

The invention discloses a component design method of a precipitation strengthening type nickel-based alloy capable of resisting laser 3D printing forming cracking, and relates to the technical field of additive manufacturing engineering. According to the method, the Nb source is introduced into the precipitation strengthening type nickel-based alloy with the total content of Al and Ti larger than or equal to 5.5 wt%, the Nb content is precisely regulated and controlled to range from 1.5 wt% to 5 wt%, the stress concentration problem in the solidification process can be effectively relieved, and therefore cracks in the laser 3D printing process are remarkably inhibited. According to the method, forming cracks can be thoroughly eliminated, it can be ensured that the alloy has the excellent high-strength characteristic, meanwhile, the comprehensive mechanical property is greatly improved, and a brand new technical means is provided for preparation of high-precision and high-performance nickel-based alloy components.

Description

Technical Field

[0001] The present invention relates to the field of additive manufacturing engineering technology, and in particular to a method for designing the composition of a precipitation-strengthened nickel-based alloy that is resistant to cracking during laser 3D printing. Background Art

[0002] Laser 3D printing technology, due to its rapid melting and solidification during the forming process, can produce finer grains and substructures within the grains, resulting in excellent overall mechanical properties that can meet the increasingly stringent operating conditions in fields such as aerospace and oil drilling. However, due to the high content of alloying elements in nickel-based superalloys and improper selection of process parameters during laser 3D printing, structural defects such as spheroidization, porosity, and cracks are easily generated during the forming process. Solidification cracks primarily form in the mushy zone during solidification. In this area, dendrites have low adhesion, and the liquid phase between the dendrites cannot flow freely to fill the shrinkage porosity, making it very easy to crack under the action of residual stress. The presence of these defects will lead to a decrease in the mechanical properties of nickel-based superalloys, seriously restricting the application of nickel-based superalloy products produced using laser 3D printing.

[0003] Adjusting the elemental composition of existing alloys based on the forming characteristics and microstructural features of laser 3D printing is considered the most effective method to eliminate forming cracks. Currently, a common method of elemental improvement is to reduce grain boundary segregation elements such as Si, Mn, C, Hf, and Nb to inhibit the formation of interdendritic liquid films during solidification. Since the Laves brittle phase formed by Nb segregation can cause cracking, reducing its content can reduce the alloy's crack sensitivity during the laser 3D printing process. While reducing the content of interdendritic segregation elements can help suppress cracking during laser 3D printing, reducing the content of these elements will seriously affect the alloy's mechanical properties, such as reduced strength and fatigue life.

[0004] Affected by high alloying, the temperature difference between the liquid and solid range of high-temperature-bearing and high-strength precipitation-strengthened nickel-based alloys is relatively wide. At the same time, the solidified parts of these alloys during laser 3D printing rapidly precipitate a large amount of γ-ray diffraction under the repeated heating of subsequent printing. ′ These high-performance nickel-based high-temperature alloys have low stacking fault energy, slow creep rate, and large phase transition stress. Compared with other metal materials, residual stress is easy to accumulate and difficult to release during printing. ′ Under the influence of phase change stress superposition, these precipitation-strengthened nickel-based alloys are very prone to cracking during laser 3D printing. Optimization of process parameters alone cannot completely suppress high-content γ-ray diffraction. ′Crack defects in precipitation-strengthened nickel-based superalloys can lead to suboptimal component performance or substandard structural integrity. Therefore, a more effective compositional improvement method is urgently needed to eliminate cracks in laser 3D-printed precipitation-strengthened nickel-based alloys. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for designing the composition of a precipitation-strengthened nickel-based alloy that is resistant to cracking during laser 3D printing, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is to provide a composition design method for a precipitation-strengthened nickel-based alloy that is resistant to cracking during laser 3D printing. By adding a Nb source, the Nb content in the precipitation-strengthened nickel-based alloy with a total Al and Ti content of ≥5.5wt% is adjusted to 1.5-5wt%.

[0008] As a further preferred embodiment of the present invention, the Nb source is Nb element, NbB2, NbN or Nb-Ni alloy.

[0009] As a further preferred embodiment of the present invention, the precipitation-strengthened nickel-based alloy having a total Al and Ti content of ≥5.5 wt % is K438.

[0010] The second technical solution of the present invention is to provide a method for preparing a precipitation-strengthened nickel-based alloy that is resistant to laser 3D printing cracking, comprising the following steps:

[0011] (1) adjusting the Nb content in a precipitation-strengthened nickel-based alloy having a total Al and Ti content of ≥5.5 wt% to 1.5-5 wt% by adding a Nb source to obtain a mixed powder;

[0012] (2) The mixed powder is prepared by laser 3D printing to obtain the precipitation-strengthened nickel-based alloy that is resistant to laser 3D printing cracking.

[0013] As a further preferred embodiment of the present invention, the Nb source is Nb element, NbB2, NbN or Nb-Ni alloy.

[0014] The present invention has no strict requirements on the method of adding Nb. It can be added during the alloy powder smelting stage or later through mechanical mixing. Because lightweight elements such as H, B, and N will volatilize from the molten pool during laser 3D printing, Nb can be added as a single element or as a secondary phase such as NbB2, NbN, or a Nb-Ni alloy.

[0015] Preferably, the method for obtaining the mixed powder in step (1) is selected from any one of the following:

[0016] Method 1: Nb powder, NbB2 powder, NbN powder or Nb-Ni alloy powder are stirred and mixed with precipitation-strengthened nickel-based alloy powder to obtain a mixed powder;

[0017] Method 2: Nb powder, NbB2 powder, NbN powder or Nb-Ni alloy powder is mixed with precipitation-strengthened nickel-based alloy powder by ball milling.

[0018] Method 3: adding Nb, NbB2, NbN or Nb-Ni alloy during the melting or atomization powder making stage of precipitation-strengthened nickel-based alloy;

[0019] As a further preferred embodiment of the present invention, the precipitation-strengthened nickel-based alloy having a total Al and Ti content of ≥5.5 wt % is K438 or GH4037.

[0020] As a further preferred embodiment of the present invention, the parameters of the laser 3D printing are: laser power 140-240 W, laser scanning speed 600-1500 mm / s, powder thickness 20-40 um, and scanning spacing 80-100 um.

[0021] As a further preferred embodiment of the present invention, the Nb source is added in step (1) by mechanical mixing.

[0022] The third technical solution of the present invention is to provide a precipitation-strengthened nickel-based alloy that is resistant to laser 3D printing cracking and is prepared by the above-mentioned preparation method.

[0023] Research has found that cracks in laser 3D printing precipitation-strengthened nickel-based alloys are mainly formed in the mushy zone during the solidification process. In this area, the dendrite bonding is low, and the liquid phase between the dendrites cannot flow freely and fill the shrinkage pores. Under the action of residual stress, cracking is very likely to occur. ′ The main elements of the phase, when Al+Ti≥5.5wt%, γ ′ The volume fraction of the phase is high, thus forming a large number of fine dispersed particles evenly distributed in the matrix, significantly improving the strength of the alloy through precipitation strengthening, and the fine and uniform γ ′ Phase distribution can inhibit crack propagation to a certain extent. Based on this, the present invention proposes a composition design method for precipitation-strengthened nickel-based alloys that are resistant to laser 3D printing cracking. By significantly increasing the Nb content, which is generally believed to cause cracking in nickel-based alloys, to 1.5-5wt%, the content of interdendritic segregation phase in the alloy is significantly increased, alleviating stress concentration during the solidification process of laser 3D printing precipitation-strengthened nickel-based alloys, thereby suppressing forming cracking. Ultimately, a laser 3D printed component with no solidification cracks in the structure and excellent mechanical properties is obtained.

[0024] The Nb content in precipitation-strengthened nickel-based alloys is very low or even contains no Nb. The present invention significantly increases the Nb element that is generally believed to cause cracking in nickel-based alloys to significantly increase the content of interdendritic segregation phase in the alloy, alleviate the stress concentration during the solidification process of laser 3D printing precipitation-strengthened nickel-based alloys, and suppress forming cracking. However, excessive Nb content will form harmful Laves brittle phases and cause cracking. The present invention limits the Nb content in precipitation-strengthened nickel-based alloys to within the range of 1.5-5wt%. At this time, the segregation phase formed by solidification is only related to the content and distribution of the Nb element, and has nothing to do with the composition of the segregation phase. In addition, since Al and Ti are the components that form γ ′ The main elements of the phase, when Al+Ti≥5.5wt%, γ ′ The volume fraction of the phase is high, thus forming a large number of fine dispersed particles evenly distributed in the matrix, significantly improving the strength of the alloy through precipitation strengthening, and the fine and uniform γ ′ Phase distribution can inhibit crack propagation to a certain extent, so the precipitation-strengthened nickel-based alloy in the present invention is a precipitation-strengthened nickel-based alloy with an Al+Ti content greater than 5.5 wt %.

[0025] The present invention is applicable to the element improvement of precipitation-strengthened nickel-based alloys, and significantly increases the content of interdendritic segregation phase of the alloy by adding Nb elements. In the final stage of solidification during laser 3D printing, under the action of thermal stress, the residual stress inside the dendrites is transferred to the residual liquid phase region between the dendrites. When the volume fraction of the liquid phase increases, the viscosity and fluidity of the liquid phase are optimized, which can effectively fill the voids and microcracks caused by solidification shrinkage. At the same time, the presence of a high content of liquid phase can buffer the strain of the solidified solid phase and avoid solidification cracking caused by stress concentration. In addition, the Nb element pins the dendrite boundaries, inhibits the premature fracture of the dendrites, and further reduces the possibility of crack propagation. Based on the above reasons, the Nb element can significantly reduce the solidification cracks of precipitation-strengthened nickel-based alloys during laser 3D printing.

[0026] The present invention has extremely high engineering significance. Reducing solidification cracks means reducing the scrap rate of parts, reducing the number of rework and repair processes, improving overall production efficiency, shortening the manufacturing cycle, and making it possible to quickly manufacture complex structural parts, which is more in line with the demand for efficient production in modern industry. Suppressing solidification cracks can significantly improve the mechanical properties of components, such as tensile strength, yield strength and elongation, and enhance the reliability and durability of parts under actual working conditions. It is of great significance for the manufacture of parts with extremely high safety requirements in fields such as aerospace, and can effectively reduce the risk of failure caused by material defects. Although laser 3D printing technology can manufacture parts with complex shapes, the crack problem limits its application. After adding the Nb element, it can reduce defects such as cracks while ensuring the formation of complex structures, and achieve high-precision and high-quality manufacturing of complex structural parts, which expands the application scope of laser 3D printing technology in the industrial field, such as the manufacture of complex blades, combustion chambers and other key components of aerospace engines.

[0027] While laser 3D printing technology can manufacture complex parts, cracking has limited its wider application. By adjusting the Nb element to an optimal range, this invention not only ensures the ability to form complex structures but also significantly reduces defects such as cracks, enabling high-precision, high-quality manufacturing of complex structural parts. This significantly expands the industrial application of laser 3D printing technology, particularly in the manufacture of key aerospace engine components such as complex blades and combustion chambers, demonstrating significant technological breakthroughs and promising applications.

[0028] The present invention has significant engineering application value. By suppressing solidification cracks, the scrap rate of parts is effectively reduced, and the rework and repair processes are reduced, thereby greatly improving the overall production efficiency and shortening the manufacturing cycle, making it possible to quickly manufacture complex structural parts and components, and fully meeting the needs of modern industry for efficient production. In addition, suppressing solidification cracks significantly improves the mechanical properties of components, including key indicators such as tensile strength, yield strength and elongation, greatly enhancing the reliability and durability of parts under actual working conditions. This is particularly important for the manufacture of parts with extremely high safety requirements in fields such as aerospace, and can effectively reduce the risk of failure due to material defects.

[0029] The present invention can also significantly reduce production costs. Although the Nb element itself has a certain cost, by reducing solidification cracking, it reduces material waste caused by cracking, improves material utilization, and thus reduces material costs overall. Furthermore, suppressing crack formation reduces the additional materials required for subsequent repair and reinforcement, further saving costs. It also reduces the number of parts scrapped and reworked due to cracking, and reduces energy consumption and equipment loss during the processing process. At the same time, it improves production efficiency, increases output per unit time, thereby reducing the processing cost per unit product, improving the company's economic benefits, and enhancing its market competitiveness.

[0030] The present invention discloses the following technical effects:

[0031] The present invention adds a Nb source to a precipitation-strengthened nickel-based alloy with a total Al and Ti content of ≥5.5wt%, adjusting the Nb content to 1.5-5wt%, thereby alleviating stress concentration during solidification and suppressing cracking during laser 3D printing. This method can eliminate cracks while maintaining the high strength of the alloy and improving its overall mechanical properties.

[0032] The present invention can significantly reduce the laser 3D printing forming defects of precipitation-strengthened nickel-based alloys, improve material utilization and production efficiency, reduce scrap rate and cost, and expand the application of laser 3D printing in the manufacture of complex structural parts, which is in line with the development trend of green manufacturing and high-end equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 These are optical microscope images, where (a) is an optical microscope image of the original composition K438 alloy formed by laser 3D printing, (b) is an optical microscope image of the K438 alloy formed by laser 3D printing containing 2 wt.% of Nb element, and (c) is an optical microscope image of the K438 alloy formed by laser 3D printing containing 3 wt.% of Nb element.

[0035] Figure 2 These are scanning electron microscope images, where (a) is a scanning electron microscope image of the original composition K438 alloy formed by laser 3D printing, (b) is a scanning electron microscope image of the K438 alloy formed by laser 3D printing containing 2 wt.% of Nb element, and (c) is a scanning electron microscope image of the K438 alloy formed by laser 3D printing containing 3 wt.% of Nb element.

[0036] Figure 3 This is a comparison chart of room temperature tensile curves of the alloy materials prepared in Comparative Example 1, Example 1, and Example 2. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0039] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0040] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0041] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0042] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in this field and are not the focus of the present invention.

[0043] Comparative Example 1

[0044] K438 is a typical representative of precipitation-strengthened nickel-based alloys. This comparative example prepared the original composition K438 alloy by laser 3D printing. The steps are as follows:

[0045] The original composition of K438 alloy powder (Cr15%, Co4%, Mo3.5%, Al 3.2%, Ti3.2%, W1.5%, Ta0.5%, C0.05%, Mn0.35%, Si0.3%, S0.01%, P0.015%, B0.01%, Zr0.1%, Ni balance) was formed into alloy samples using laser 3D printing equipment. The forming parameters used were: laser power 160W, laser scanning speed 1000mm / s, powder thickness 30μm, and scanning spacing 100μm.

[0046] Optical microscope images of the original K438 alloy formed by laser 3D printing Figure 1 As shown in (a), it can be seen that there are a large number of solidification cracks distributed along the forming direction.

[0047] Scanning electron microscope images of the original K438 alloy formed by laser 3D printing Figure 2 As shown in (a), it can be seen that the content of interdendritic segregation phase in the original composition K438 alloy is extremely low, and its volume fraction is less than 2%. It can also be seen that there are a large number of dislocations in the original composition K438 alloy, which also indirectly reflects the presence of a large amount of residual stress in the alloy structure. Due to the accumulation of residual stress, a large number of cracks exist in the alloy forming structure.

[0048] The room temperature tensile curve of the original composition K438 alloy formed by laser 3D printing is shown in Figure 3 It can be seen that due to the presence of a large number of cracks in the formed structure of K438 alloy, the alloy exhibits extremely poor tensile properties (tensile strength < 600 MPa, elongation < 5%).

[0049] Example 1

[0050] Preparation of a precipitation-strengthened nickel-based alloy that resists laser 3D printing cracking:

[0051] (1) Using Nb particles as the Nb source, Nb and K438 alloy powder (Cr15%, Co4%, Mo3.5%, Al3.2%, Ti3.2%, W1.5%, Ta0.5%, C0.05%, Mn0.35%, Si0.3%, S0.01%, P0.015%, B0.01%, Zr0.1%, Ni balance) were stirred and mixed in alcohol at a mass ratio of 2:98 (i.e., the mass fraction of Nb was 2 wt.%) to obtain a mixed powder;

[0052] (2) drying the mixture obtained in step (1) at 80° C. for 4 h;

[0053] (3) The mixed powder prepared in step (2) was formed into an alloy sample using a laser 3D printing device. The forming parameters used were: laser power 160 W, laser scanning speed 1000 mm / s, powder thickness 30 μm, and scanning spacing 100 μm.

[0054] The optical microscope image of the laser 3D printed K438 alloy containing 2wt.% Nb is shown in the figure. Figure 1 As shown in (b), it can be seen that after adding 2wt.% Nb element, the forming cracks in the alloy are completely eliminated.

[0055] The scanning electron microscope image of the laser 3D printed K438 alloy containing 2wt.% Nb is shown in the figure. Figure 2 As shown in (b), compared with the original composition K438 alloy of comparative example 1 ( Figure 2 Compared to (a), the addition of 2 wt.% Nb significantly increases the amount of interdendritic segregation phase in the alloy, reaching a volume fraction greater than 15%. This is because the addition of Nb increases the amount of interdendritic liquid phase during solidification, leading to an increase in the amount of interdendritic segregation phase in the final microstructure. Dislocations are essentially absent from the alloy structure. This is because the addition of Nb increases the amount of interdendritic liquid phase. When the volume fraction of the residual liquid phase is sufficiently high, the liquid phase retains good fluidity, effectively filling voids and microcracks generated by solidification shrinkage. Furthermore, the presence of a high liquid phase content can buffer the strain of the solidified solid phase, preventing solidification cracking caused by stress concentration.

[0056] The room temperature tensile curve of the laser 3D printed K438 alloy containing 2wt.% Nb is shown in Figure 3 It can be seen that the addition of 2wt.% Nb element eliminates the cracks in the alloy, and the tensile strength reaches 1120MPa and the elongation reaches 24.2%, which are significantly higher than the mechanical properties of the original composition K438 alloy.

[0057] Example 2

[0058] Preparation of a precipitation-strengthened nickel-based alloy that resists laser 3D printing cracking:

[0059] (1) Using Nb particles as the Nb source, Nb and K438 alloy powder (Cr15%, Co4%, Mo3.5%, Al3.2%, Ti3.2%, W1.5%, Ta0.5%, C0.05%, Mn0.35%, Si0.3%, S0.01%, P0.015%, B0.01%, Zr0.1%, Ni balance) were stirred and mixed in alcohol at a mass ratio of 3:97 (i.e., the mass fraction of Nb was 3 wt.%) to obtain a mixed powder;

[0060] (2) drying the mixture obtained in step (1) at 80° C. for 4 h;

[0061] (3) The mixed powder prepared in step (2) was formed into an alloy sample using a laser 3D printing device. The forming parameters used were: laser power 160 W, laser scanning speed 1000 mm / s, powder thickness 30 μm, and scanning spacing 100 μm.

[0062] Optical microscope images of laser 3D printed K438 alloy containing 3wt.% Nb element are shown in the figure below. Figure 1 As shown in (c), it can be seen that after adding 3wt.% Nb element, the forming cracks in the alloy are completely eliminated.

[0063] The scanning electron microscope image of the laser 3D printed K438 alloy containing 3wt.% Nb is shown in the figure. Figure 2 As shown in (c), it can be seen that the content of interdendritic segregation phase in the alloy increases significantly, and its volume fraction is greater than 10%.

[0064] Combine Figure 1 (c) and Figure 2 (c) It can be seen that the microstructure of the alloy after adding Nb element is significantly different from that of the precipitation-strengthened nickel-based alloy with the original composition.

[0065] The room temperature tensile curve of the laser 3D printed K438 alloy containing 3wt.% Nb is shown in Figure 3 Due to the elimination of cracks in the formed alloy, its strength and plasticity are significantly improved compared to the original composition K438 alloy, with a tensile strength of 1088 MPa and an elongation of 20.3%.

[0066] Example 3

[0067] Preparation of a precipitation-strengthened nickel-based alloy that resists laser 3D printing cracking:

[0068] (1) Using Nb single-substance particles as the Nb source, Nb single-substance and K438 alloy powder (Cr15%, Co4%, Mo3.5%, Al3.2%, Ti3.2%, W1.5%, Ta0.5%, C0.05%, Mn0.35%, Si0.3%, S0.01%, P0.015%, B0.01%, Zr0.1%, Ni balance) were stirred and mixed in alcohol at a mass ratio of 1.5:98.5 (i.e., the mass fraction of Nb was 1.5wt.%) to obtain a mixed powder;

[0069] (2) drying the mixture obtained in step (1) at 80° C. for 4 h;

[0070] (3) The mixed powder prepared in step (2) was formed into an alloy sample using a laser 3D printing device. The forming parameters used were: laser power 160 W, laser scanning speed 1000 mm / s, powder thickness 30 μm, and scanning spacing 100 μm.

[0071] In this embodiment, after adding 1.5 wt.% of Nb element, the content of the interdendritic segregation liquid phase is significantly increased, and the forming crack elimination effect in the alloy is obvious.

[0072] Example 4

[0073] Preparation of a precipitation-strengthened nickel-based alloy that resists laser 3D printing cracking:

[0074] (1) Using Nb particles as the Nb source, Nb and K438 alloy powder (Cr15%, Co4%, Mo3.5%, Al3.2%, Ti3.2%, W1.5%, Ta0.5%, C0.05%, Mn0.35%, Si0.3%, S0.01%, P0.015%, B0.01%, Zr0.1%, Ni balance) were stirred and mixed in alcohol at a mass ratio of 5:95 (i.e., the mass fraction of Nb was 5 wt.%) to obtain a mixed powder;

[0075] (2) drying the mixture obtained in step (1) at 80° C. for 4 h;

[0076] (3) The mixed powder prepared in step (2) was formed into an alloy sample using a laser 3D printing device. The forming parameters used were: laser power 160 W, laser scanning speed 1000 mm / s, powder thickness 30 μm, and scanning spacing 100 μm.

[0077] The results show that after adding 5wt.% Nb element, the content of interdendritic segregation liquid phase increases significantly, and the forming crack elimination effect in the alloy is obvious.

[0078] Comparative Example 2

[0079] The only difference from Example 1 is that in step (1), a Nb source is added so that the mass fraction of Nb in the alloy is 0.5 wt.%.

[0080] The results show that after adding 0.5wt.% Nb element, the content of interdendritic segregation liquid phase does not increase significantly, and some cracks still exist in the alloy.

[0081] Comparative Example 3

[0082] The only difference from Example 1 is that in step (1), a Nb source is added so that the mass fraction of Nb in the alloy is 1 wt.%.

[0083] The results show that after adding 1wt.% Nb element, the content of interdendritic segregation liquid phase does not increase significantly, and some cracks still exist in the alloy.

[0084] Comparative Example 4

[0085] The only difference from Example 1 is that in step (1), a Nb source is added so that the mass fraction of Nb in the alloy is 6 wt.%.

[0086] The results show that after adding 6wt.% Nb element, the content of interdendritic segregation liquid phase does not increase significantly, and some cracks still exist in the alloy.

[0087] Comparative Example 5

[0088] The only difference from Example 1 is that the Al content in the raw material K438 is adjusted to 2.2%.

[0089] The results show that when the Al+Ti content is less than 5.5%, even if a certain amount of Nb element is added, the cracks in the alloy cannot be completely eliminated, resulting in the alloy exhibiting extremely poor tensile properties (tensile strength <700 MPa, elongation <6%).

[0090] The composition design method for a precipitation-strengthened nickel-based alloy resistant to laser 3D printing cracking, provided by this invention, is suitable for elemental modification of precipitation-strengthened nickel-based alloys. By adding the element Nb, the content of interdendritic segregation phases is significantly increased. However, excessive Nb content can form harmful Laves brittle phases, leading to cracking. Therefore, the Nb content should be controlled between 1.5 and 5 wt.%. At this point, the segregation phase formed during solidification is solely dependent on the Nb content and distribution, and not on its composition.

[0091] In the final stage of solidification, under the action of thermal stress, the residual stress inside the dendrite is transferred to the residual liquid phase between the dendrites. When the volume fraction of the liquid phase increases, the viscosity and fluidity of the liquid phase are optimized, which can effectively fill the voids and microcracks caused by solidification shrinkage. At the same time, the presence of a high content of liquid phase can buffer the strain of the solidified solid phase and avoid solidification cracking caused by stress concentration. In addition, the Nb element pins the dendrite boundaries, inhibiting the premature fracture of the dendrites and further reducing the possibility of crack propagation. Based on the above reasons, the Nb element can play a role in inhibiting the cracking of precipitation-strengthened nickel-based alloys formed by laser 3D printing.

[0092] This invention significantly increases the interdendritic segregation phase content of nickel-based alloys by introducing Nb, a widely believed element that causes cracking in nickel-based alloys. This alleviates stress concentration during the solidification process of precipitation-strengthened nickel-based alloys formed by laser 3D printing, thereby suppressing cracking during forming. The result is a laser 3D-printed component with no solidification cracks and excellent mechanical properties.

[0093] The present invention opens up broader application prospects for laser 3D printing-formed nickel-based alloys, making their application in high-end equipment manufacturing fields such as aerospace, energy, and petrochemicals more extensive and in-depth, helping to promote technological progress and industrial upgrading in these industries, and meet the growing demand for high-performance, complex structural components. At the same time, it promotes the research and development of high-performance alloy materials, provides new ideas and methods for the research and development of high-performance nickel-based alloys, optimizes the solidification behavior and properties of alloys through element regulation, and stimulates the research and development and innovation of new high-performance alloy materials. It is expected to develop more high-performance alloy materials that meet the requirements of special working conditions and promote the development of materials science and engineering.

[0094] The present invention is in line with the development trend of the manufacturing industry. As the manufacturing industry develops towards high-end, intelligent and green directions, it meets the manufacturing industry's demand for high-quality and high-performance parts manufacturing.

[0095] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A composition design method for a precipitation-strengthened nickel-based alloy resistant to laser 3D printing cracking, characterized in that: By adding a Nb source, the Nb content in the precipitation-strengthened nickel-based alloy with a total Al and Ti content of ≥5.5 wt% is adjusted to 1.5-5 wt%.

2. The composition design method according to claim 1, characterized in that: The Nb source is Nb element, NbB2, NbN or Nb-Ni alloy.

3. The composition design method according to claim 1, characterized in that: The precipitation-strengthened nickel-based alloy with a total Al and Ti content of ≥5.5wt% is K438 or GH4037.

4. A method for preparing a precipitation-strengthened nickel-based alloy that is resistant to laser 3D printing cracking, characterized in that: The following steps are involved: (1) adjusting the Nb content in a precipitation-strengthened nickel-based alloy having a total Al and Ti content of ≥5.5 wt% to 1.5-5 wt% by adding a Nb source to obtain a mixed powder; (2) The mixed powder is prepared by laser 3D printing to obtain the precipitation-strengthened nickel-based alloy that is resistant to laser 3D printing cracking.

5. The preparation method according to claim 4, characterized in that The Nb source is Nb element, NbB2, NbN or Nb-Ni alloy.

6. The preparation method according to claim 4, characterized in that The precipitation-strengthened nickel-based alloy with a total Al and Ti content of ≥5.5wt% is K438 or GH4037.

7. The preparation method according to claim 4, characterized in that The parameters of the laser 3D printing are: laser power 140-240W, laser scanning speed 600-1500mm / s, powder thickness 20-40um, and scanning spacing 80-100um.

8. The preparation method according to claim 4, characterized in that In step (1), the Nb source is added by mechanical mixing.

9. A precipitation-strengthened nickel-based alloy resistant to laser 3D printing cracking prepared by the preparation method according to any one of claims 4 to 8.

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