High-density laser powder bed molten high-temperature alloy difficult to weld and preparation method and application thereof

Abstract

The invention discloses a high-density laser powder bed molten high-temperature alloy difficult to weld as well as a preparation method and application of the high-temperature alloy. The preparation method comprises the steps that alloy powder serves as a raw material, and the high-temperature alloy difficult to weld is prepared through the laser powder bed melting technology of double laser beams; wherein the laser heat source of the first laser beam is in Gaussian distribution, and the laser volume energy density is 40-55 J / mm < 3 >; a laser heat source of the second laser beam is flat-topped light or a transverse elliptical light beam, the laser volume energy density is 30-40 J / mm < 3 >, and the starting time interval of the first laser beam and the second laser beam is 0.15-0.25 s. According to the method, the second beam of laser is introduced into the laser powder bed melting technology, the type and the interval time of the second beam of laser are adjusted and optimized, large-size printing defects are annihilated in situ, the forming quality of the high-temperature alloy difficult to weld is remarkably improved, and a new solution is provided for preparing the high-performance and high-density alloy.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology for metallic materials, specifically relating to a high-density laser powder bed melting method for preparing a difficult-to-weld high-temperature alloy and its application. Background Technology

[0002] Laser powder bed fusion (LPBF) technology, as an advanced additive manufacturing method, has significant application value in the manufacture of high-temperature components in aerospace, energy, and power industries, especially suitable for the integrated forming of complex and difficult-to-weld high-temperature alloy components. However, due to the high γ′ phase content and high alloying characteristics of these alloys, cracks, porosity, and incomplete fusion defects are easily generated during traditional Gaussian single-laser LPBF processes, resulting in insufficient density of the formed parts and severely restricting their service performance under high-temperature and high-pressure environments. Therefore, there is an urgent need to develop a novel LPBF preparation process that can simultaneously optimize density and mechanical properties, achieving high density, low defects, and controllable performance in difficult-to-weld high-temperature alloys. Summary of the Invention

[0003] The main objective of this invention is to provide a high-density laser powder bed melting method for preparing and applying a difficult-to-weld high-temperature alloy, thereby overcoming the shortcomings of the prior art.

[0004] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: This invention provides a method for preparing a high-density laser powder bed melting technique for welding difficult-to-weld high-temperature alloys, comprising: using alloy powder as raw material and employing a dual-laser-beam laser powder bed melting technique to prepare the difficult-to-weld high-temperature alloy; wherein the process parameters used in the laser powder bed melting technique include: the laser heat source of the first laser beam has a Gaussian distribution, and the laser volume energy density is 40~55 J / mm². 3 The second laser beam's heat source is a flat-top beam or a transverse elliptical beam, with a laser volumetric energy density of 30~40 J / mm². 3 The start-up time interval between the first laser beam and the second laser beam is 0.15~0.25 s.

[0005] The present invention also provides a high-density laser powder bed fusion high-temperature alloy that is difficult to weld, prepared by the aforementioned preparation method.

[0006] This invention also provides the application of the aforementioned high-density laser powder bed fusion of difficult-to-weld high-temperature alloys in the manufacture of high-temperature components in the aerospace or energy power fields.

[0007] Compared with existing technologies, the advantages of this invention are as follows: This invention proposes a method for preparing high-density laser powder bed fusion nickel-based superalloys. Its advantages are not only in obtaining extremely high density (d≥99.96%), but also in achieving active intervention and optimization of the defect forming process within the energy density window of unfused defects (40~55 J / mm³) by precisely controlling the second laser beam (flat-top beam / transverse elliptical beam) and its start-up sequence (0.15~0.25 s). At the same time, this method can not only annihilate large-size defects in situ, but also simultaneously optimize the molten pool structure and refine the microstructure, thereby significantly improving the comprehensive mechanical properties of difficult-to-weld superalloys. This provides an innovative process solution with high reliability for the direct manufacturing of high-performance key components in aerospace and other fields. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a microstructure diagram of the difficult-to-weld high-temperature alloy prepared in Example 1 of the present invention; Figure 2 This is a microstructure diagram of the difficult-to-weld high-temperature alloy prepared in Example 2 of the present invention; Figure 3 This is a microstructure diagram of the difficult-to-weld high-temperature alloy prepared in Example 3 of the present invention; Figure 4 This is a microstructure diagram of the difficult-to-weld high-temperature alloy prepared in Comparative Example 1 of this invention; Figure 5 This is a microstructure diagram of the difficult-to-weld high-temperature alloy prepared in Comparative Example 2 of the present invention; Figure 6 This is a microstructure diagram of the difficult-to-weld high-temperature alloy prepared in Comparative Example 3 of the present invention; Figure 7 This is a microstructure diagram of the difficult-to-weld high-temperature alloy prepared in Comparative Example 4 of this invention; Figure 8 This is a microstructure diagram of the difficult-to-weld high-temperature alloy prepared in Comparative Example 5 of the present invention; Figure 9 This is a microstructure diagram of the difficult-to-weld high-temperature alloy prepared in Comparative Example 6 of this invention; Figure 10 This is a microstructure diagram of the difficult-to-weld high-temperature alloy prepared in Comparative Example 7 of this invention; Figure 11This is a microstructure diagram of the difficult-to-weld high-temperature alloy prepared in Comparative Example 8 of this invention; Figure 12 This is a microstructure diagram of the difficult-to-weld high-temperature alloy prepared in Comparative Example 9 of this invention. Detailed Implementation

[0010] In view of the deficiencies of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. This invention provides a high-density laser powder bed melting process for preparing difficult-to-weld high-temperature alloys, overcoming the technical barrier of poor forming quality of existing single Gaussian lasers in difficult-to-weld high-temperature alloys. By controlling the type and time interval of dual laser beams, the active control of the molten pool morphology and solidification behavior is achieved, ultimately producing high-density, high-performance difficult-to-weld high-temperature alloys.

[0011] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0012] Specifically, as one aspect of the technical solution of the present invention, the method for preparing a high-density laser powder bed melting difficult-to-weld high-temperature alloy includes: using alloy powder as raw material, and using laser powder bed melting technology with dual laser beams to prepare the difficult-to-weld high-temperature alloy; The process parameters used in the laser powder bed melting technology include: the laser heat source of the first laser beam has a Gaussian distribution, and the laser volume energy density is 40~55 J / mm². 3 Preferably, the laser volumetric energy density can be, for example, but not limited to, 40 J / mm². 3 45 J / mm 3 50 J / mm 3 55 J / mm 3 The range between any one or any two of them; The laser heat source for the second laser beam is a flat-top beam or a transverse elliptical beam, with a laser volumetric energy density of 30~40 J / mm². 3 Preferably, the laser volumetric energy density can be, for example, but not limited to, 30 J / mm². 3 35 J / mm 3 40 J / mm 3 The range between any one or any two of them; Furthermore, the start-up time interval between the first laser beam and the second laser beam is 0.15~0.25 s. Preferably, the interval between laser beams can be any one of, but not limited to, 0.15 s, 0.20 s, 0.25 s, or any range between any two.

[0013] In this invention, the laser energy density and the start-up timing of the dual-beam lasers are the core of the synergistic control of the additive manufacturing thermal process: excessive energy density can easily lead to overheating of the molten pool, resulting in porosity and coarse microstructure, while insufficient energy density can cause incomplete fusion and spheroidization defects; conversely, excessively short intervals between the dual laser beams can cause heat accumulation, microstructure coarsening, and molten pool interference, while excessively long intervals can lead to poor interlayer bonding and stress concentration due to interruption of the temperature field. These two factors essentially determine heat accumulation, cooling rate, and molten pool behavior. Any mismatch will disrupt process stability and trigger a series of problems ranging from microscopic defects to macroscopic deformation.

[0014] In some preferred embodiments, the alloy powder includes, but is not limited to, nickel-based alloy powder.

[0015] Furthermore, the particle size distribution of the nickel-based alloy powder is 15~53 μm.

[0016] In some preferred embodiments, the process parameters used in the laser powder bed melting technology include: the laser power of the first laser beam is 270~300 W, the scanning speed is 1400~1600 mm / s, and the scanning spacing is 0.09~0.11 mm.

[0017] Preferably, the laser power can be, for example, but not limited to, 270 W, 285 W, or 300 W; the scanning speed can be, for example, but not limited to, any one of 1400 mm / s, 1500 mm / s, or 1600 mm / s, or a range between any two; and the scanning spacing can be, for example, but not limited to, any one of 0.09 mm, 0.10 mm, or 0.11 mm, or a range between any two.

[0018] In some preferred embodiments, the process parameters used in the laser powder bed melting technology include: a powder layer thickness of 0.03~0.05 mm, a spot diameter of 0.09~0.11 mm, and an interlayer rotation angle of 67°.

[0019] Preferably, the powder layer thickness can be, for example, but not limited to, any one of 0.03 mm, 0.04 mm, 0.05 mm or any two of them; the spot diameter can be, for example, but not limited to, any one of 0.09 mm, 0.10 mm, 0.11 mm or any two of them.

[0020] In some preferred embodiments, the process parameters used in the laser powder bed melting technology include: a laser power of 200~220 W for the second laser beam, a scanning speed of 1400~1600 mm / s, a scanning spacing of 0.09~0.11 mm, a spot diameter of 0.09~0.11 mm, and an interlayer rotation angle of 67°.

[0021] Preferably, the laser power can be, for example, but not limited to, 200 W, 210 W, or 220 W; the scanning speed can be, for example, but not limited to, any one or any two of 1400 mm / s, 1500 mm / s, or 1600 mm / s; the scanning spacing can be, for example, but not limited to, any one or any two of 0.09 mm, 0.10 mm, or 0.11 mm; and the spot diameter can be, for example, but not limited to, any one or any two of 0.09 mm, 0.10 mm, or 0.11 mm.

[0022] In some preferred embodiments, the laser heat source of the second laser beam is a flat-top light.

[0023] Another aspect of the present invention provides a high-density laser powder bed fusion high-temperature alloy prepared by the aforementioned preparation method.

[0024] In some preferred embodiments, the relative density of the difficult-to-weld high-temperature alloy is ≥99.85%.

[0025] Furthermore, the relative density of the difficult-to-weld high-temperature alloy is ≥99.89%.

[0026] Furthermore, the relative density of the difficult-to-weld high-temperature alloy is ≥99.96%.

[0027] Another aspect of the present invention provides the application of the aforementioned high-density laser powder bed fusion of difficult-to-weld high-temperature alloys in the manufacture of high-temperature components in the aerospace or energy and power fields.

[0028] This invention introduces a second laser beam into laser powder bed melting technology and optimizes the type and interval of the second laser beam to annihilate large-size printing defects in situ, significantly improving the forming quality of difficult-to-weld high-temperature alloys and providing a new solution for the preparation of high-performance, high-density alloys.

[0029] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0030] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0031] Example 1 A process for preparing high-density laser powder bed molten nickel-based superalloys includes: Commercial IN939 nickel-based alloy powder was selected. The laser heat source of the first laser beam had a Gaussian distribution, and the laser volume energy density was 47.5 J / mm². 3 The laser power was 285 W, the scanning speed was 1500 mm / s, the scanning interval was 0.10 mm, the powder layer thickness was 0.04 mm, and the interlayer rotation angle was 67°. The second laser beam used a flat-top laser as the heat source, with a laser volumetric energy density of 35 J / mm². 3 The laser power is 210 W, the scanning speed is 1500 mm / s, the scanning spacing is 0.10 mm, the interlayer rotation angle is 67°, and the start-up interval between the two laser beams is 0.20 s.

[0032] The microstructure of the IN939 nickel-based alloy prepared in this embodiment is shown in the figure below. Figure 1 As shown, no obvious defects were observed in the three sections XY, XZ and YZ, indicating good bonding between the layers and the relative density of 99.99%.

[0033] Example 2 The difference from Example 1 is that the second laser beam is a transverse elliptical laser. Its microstructure image is shown below. Figure 2 As shown, the XZ section has a small number of pores, the channel / interlayer bonding effect is good, and the relative density is 99.96%.

[0034] Example 3 The difference from Example 1 is that the second laser beam is a flat-top laser, and the interval between laser beams is 0.25 s. Its microstructure is shown below. Figure 3 As shown, the relative density is 99.75%.

[0035] Comparative Example 1 The difference from Example 1 is that only a single beam of Gaussian laser is used as the heat source input, and its microstructure is shown in the figure. Figure 4 As shown, the XZ and YZ sections have the largest relative unfused porosity, and the molten pool is increasingly uneven, with a relative density of 99.16%.

[0036] Comparative Example 2 The method is the same as in Example 1, except that only the second laser beam (flat-top beam) is used as a single heat source, and the laser volumetric energy density is 35 J / mm³; its microstructure is shown in the figure. Figure 5As shown, the molten pool morphology indicates that due to insufficient initial input energy, the powder layer failed to form an effective continuous molten pool, only local melting and significant spheroidization occurred, with almost no dense solid formation and a relative density of less than 90%.

[0037] Comparative Example 3 The method is the same as in Example 1, except that the volumetric energy density of the first laser beam is 30 J / mm³; its microstructure is shown in the figure. Figure 6 As shown, the molten pool morphology indicates that the molten pool generated by the first laser beam is shallow and narrow, failing to achieve sufficient interlayer remelting, resulting in a large number of unfused defects in the YZ section. Although the second laser beam performed subsequent processing, the poor basic fusion made it difficult to completely eliminate the defects, with a relative density of 98.35%.

[0038] Comparative Example 4 The method is the same as in Example 1, except that the volumetric energy density of the first laser beam is 60 J / mm³; its microstructure is shown in the figure. Figure 7 As shown, the molten pool morphology indicates that the excessive energy of the first laser beam caused instability in the molten pool, resulting in spatter and inducing a keyhole effect, leaving numerous irregular pores in the XZ section. The subsequent action of the second laser beam could not eliminate these deep-seated pores, with a relative density of 98.55%.

[0039] Comparative Example 5 The method is the same as in Example 1, except that the laser volume energy density of the second laser beam is 25 J / mm³, and its microstructure is shown in the figure. Figure 8 As shown, the morphology of the molten pool indicates that the energy of the second laser beam is insufficient, and its thermal effect can only slightly modify the surface. It fails to effectively remelt and optimize the microstructure of the molten pool edge and interlayer bonding area generated by the first laser beam, leaving some unfused defects with a relative density of 98.70%.

[0040] Comparative Example 6 The method is the same as in Example 1, except that the volumetric energy density of the second laser beam is 55 J / mm³; its microstructure is shown in the figure. Figure 9 As shown, the molten pool morphology indicates that the second laser beam had excessive energy, which is equivalent to two high-peak energy inputs to the same area in a very short time, resulting in local overheating, abnormally large grains, and new pores in the center of the molten pool due to excessive evaporation, with a relative density of 98.60%.

[0041] Comparative Example 7 The method is the same as in Example 1, except that the laser heat source of the second laser beam is Gaussian distributed; its microstructure is shown in the figure. Figure 10As shown, the morphology of the molten pool indicates that due to the excessively high energy at the center of the Gaussian beam and the sharp drop in energy at the edge, its secondary effect on the molten channel is uneven. An overheating zone is formed at the center of the molten channel, while the energy is insufficient at the junction of the molten channels, resulting in uneven effects of tissue refinement and defect repair, with a relative density of 99.22%.

[0042] Comparative Example 8 The method is the same as in Example 1, except that the start-up time interval between the first laser beam and the second laser beam is 0.1 s; its microstructure image is as follows. Figure 11 As shown, the molten pool morphology indicates that, since the molten pool formed by the first laser has not yet begun to solidify when the second laser is activated, the heat from the two lasers accumulates severely, leading to an expansion of the molten pool, increased spatter, coarsening of the microstructure, and possible thermal cracking. The relative density is 99.18%.

[0043] Comparative Example 9 The method is the same as in Example 1, except that the time interval between the start-up of the first laser beam and the second laser beam is 0.3 s; its microstructure image is as follows. Figure 12 As shown, the molten pool morphology indicates that the molten pool formed by the first laser beam has completely solidified and cooled to a lower temperature. The effect of the second laser beam is equivalent to re-cladding on the cold substrate. The thermal cycle is discontinuous, resulting in incomplete fusion and microcracks at the interlayer bonding. The relative density is 98.65%.

[0044] When the second laser beam is a flat-top beam, although the first molten pool has partially solidified, it still maintains a high temperature gradient and a certain volume fraction of liquid phase. This allows the Marangoni convection inside the molten pool to be re-stabilized when the flat-top laser beam arrives. At this time, the convection intensity is moderate, and the liquid metal circulates sufficiently, which can not only improve the stability of the molten pool, but also effectively remelt the incompletely fused areas between the channels, achieving full backfilling and thus almost completely eliminating porosity.

[0045] In contrast, when the second beam uses a transverse elliptical beam, the molten pool remains in an overflowing state during the first phase, with significant surface oscillations. Convection in the molten pool is mainly concentrated in the upper shallow layer, making it difficult to penetrate downwards to some unfused valley areas, resulting in insufficient backfilling. Conversely, the transverse elliptical beam, due to its concentrated energy in the transverse plane, can reactivate the molten pool and expand wettability. However, due to the unstable energy in the longitudinal direction, insufficient remelting depth may occur, thus still resulting in a small number of defects.

[0046] In summary, the remelting heat effect of the flat-top light and the thermal history corresponding to the 0.2 s delay are in a relatively ideal intermediate state, which makes the convection intensity of the molten pool, the liquid phase volume distribution and the remelting depth reach the best balance, thus achieving a near-dense forming quality.

[0047] This invention proposes a high-density laser powder bed molten nickel-based superalloy preparation process, based on the energy density range of printing defects (40~55 J / mm). 3 By adjusting and optimizing the type of the second laser beam (flat-top beam / transverse elliptical beam) and the interval time (0.15~0.25 s), large-sized printed pores are annihilated in situ, significantly improving the forming quality of nickel-based superalloys with a relative density ≥99.96%, providing a new solution for the preparation of high-performance, high-density alloys.

[0048] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0049] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.

Claims

1. A method for preparing a difficult-to-weld high-temperature alloy by high-density laser powder bed melting, characterized in that, include: A difficult-to-weld high-temperature alloy was prepared using alloy powder as raw material and a dual-laser-beam laser powder bed melting technique. The process parameters for this laser powder bed melting technique included: the first laser beam had a Gaussian heat source distribution and a laser volumetric energy density of 40–55 J / mm². 3 The second laser beam's heat source is a flat-top beam or a transverse elliptical beam, with a laser volumetric energy density of 30~40 J / mm². 3 The start-up time interval between the first laser beam and the second laser beam is 0.15~0.25 s.

2. The preparation method according to claim 1, characterized in that: The alloy powder includes nickel-based alloy powder; preferably, the particle size distribution of the nickel-based alloy powder is 15~53 μm.

3. The preparation method according to claim 1, characterized in that, The process parameters used in the laser powder bed melting technology include: the laser power of the first laser beam is 270~300 W, the scanning speed is 1400~1600 mm / s, and the scanning spacing is 0.09~0.11 mm.

4. The preparation method according to claim 1, characterized in that, The process parameters used in the laser powder bed melting technology include: powder layer thickness of 0.03~0.05 mm, spot diameter of 0.09~0.11 mm, and interlayer rotation angle of 67°.

5. The preparation method according to claim 1, characterized in that, The process parameters used in the laser powder bed melting technology include: the laser power of the second laser beam is 200~220 W, the scanning speed is 1400~1600 mm / s, the scanning spacing is 0.09~0.11 mm, the spot diameter is 0.09~0.11 mm, and the interlayer rotation angle is 67°.

6. The preparation method according to claim 1, characterized in that: The laser heat source for the second laser beam is a flat-top beam.

7. A high-density laser powder bed fusion difficult-to-weld high-temperature alloy prepared by the preparation method of any one of claims 1-6.

8. The preparation method according to claim 7, characterized in that: The relative density of the difficult-to-weld high-temperature alloy is ≥99.85%.

9. The preparation method according to claim 8, characterized in that: The relative density of the difficult-to-weld high-temperature alloy is ≥99.89%, preferably ≥99.96%.

10. The application of the high-density laser powder bed fusion difficult-to-weld high-temperature alloy according to any one of claims 7-9 in the manufacture of high-temperature components in the aerospace or energy power fields.

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