阅读说明：本技术 一种粗化沉淀强化镍基高温合金晶粒的激光粉床熔融成形方法 (Laser powder bed fusion forming method for coarsening precipitation strengthening nickel-based superalloy grains ) 是由 郭川 朱强 徐振 李干 周阳 于 2020-12-30 设计创作，主要内容包括：本发明提供一种粗化沉淀强化镍基高温合金晶粒的激光粉床熔融成形方法,所述方法通过在连续激光粉床熔融成形前,向沉淀强化镍基高温合金粉末中掺入稀土元素氧化物颗粒,稀土元素氧化物颗粒与沉淀强化镍基高温合金粉末在连续激光作用下相互作用,从而达到了晶粒粗化的效果,通过粗化晶粒,减少高温下脆弱的晶界的数量,显著提高了沉淀强化镍基高温合金的高温力学性能。(The invention provides a laser powder bed fusion forming method for coarsening precipitation strengthening nickel-based superalloy grains, which is characterized in that rare earth element oxide particles are doped into precipitation strengthening nickel-based superalloy powder before a continuous laser powder bed fusion forming process, and the rare earth element oxide particles and the precipitation strengthening nickel-based superalloy powder interact under the action of continuous laser, so that the effect of coarsening the grains is achieved, the number of fragile grain boundaries at high temperature is reduced by coarsening the grains, and the high-temperature mechanical property of the precipitation strengthening nickel-based superalloy is obviously improved.)

1. A laser powder bed fusion forming method for coarsening precipitation strengthening nickel-base superalloy crystal grains is characterized by comprising the following steps: mixing rare earth element oxide particles and precipitation-strengthened nickel-based superalloy powder, and performing laser powder bed fusion forming by using continuous laser to obtain a formed piece.

2. The method according to claim 1, wherein the precipitation-strengthened nickel-base superalloy powder has a particle size D50 of 20 to 35 μ ι η;

preferably, the particle size range of the precipitation strengthening nickel-based superalloy powder is 15-53 mu m;

preferably, the precipitation strengthened nickel-base superalloy is IN738LC precipitation strengthened nickel-base superalloy.

3. The method according to claim 1 or 2, wherein the mass ratio of the precipitation-strengthened nickel-base superalloy powder to the rare earth oxide particles is 50-5000: 1, preferably 1000-3000: 1;

preferably, the rare earth element oxide particles are yttrium oxide particles;

preferably, the particle size of the rare earth element oxide particles is 40-200 nm, preferably 60-150 nm.

4. The method according to any one of claims 1 to 3, wherein the continuous laser has a beam diameter of 50 to 130 μm;

preferably, the power of the continuous laser is 200-350W;

preferably, the scanning speed of the continuous laser is 800-2000 mm/s;

preferably, the scanning interval of the continuous laser is 60-120 μm.

5. The method according to any one of claims 1 to 4, wherein the device for laser powder bed fusion forming is a laser powder bed fusion device;

preferably, the mixed rare earth element oxide particles and the precipitation-strengthened nickel-base superalloy powder are placed in a forming cavity of laser powder bed melting equipment to form a powder layer, and then the laser powder bed melting forming is carried out;

preferably, the thickness of the powder layer is 30-50 μm.

6. The method of claim 5, wherein prior to forming the powder layer, evacuating a forming chamber of the laser powder bed fusion apparatus;

preferably, the vacuum degree after vacuumizing is 3-10 Pa.

7. The method of claim 5, wherein the powder layer is preheated prior to the laser powder bed fusion forming;

preferably, the temperature of the preheating is more than or equal to 100 ℃.

8. The method according to any one of claims 1 to 7, wherein the laser powder bed fusion forming is performed in a protective atmosphere;

preferably, the protective atmosphere comprises argon and/or helium.

9. The method according to any one of claims 1 to 8, wherein a formed piece formed by melting and forming the laser powder bed is cooled to obtain a precipitation-strengthened nickel-based superalloy part;

preferably, the cooling comprises natural cooling.

10. A method according to any one of claims 1 to 9, characterized in that the method comprises the steps of:

(1) vacuumizing a forming cavity of laser powder bed melting equipment to 3-10 Pa, and filling protective atmosphere;

(2) mixing precipitation-strengthened nickel-based high-temperature alloy powder with the particle size range of 15-53 mu m and the particle size D50 of 20-35 mu m and yttrium oxide particles with the particle size of 40-200 nm according to the mass ratio of 50-5000: 1, placing the mixture in a forming cavity of laser powder bed melting equipment under a protective atmosphere to form a powder layer with the particle size of 30-50 mu m, and preheating the powder layer until the temperature is more than or equal to 100 ℃;

(3) and melting and forming the powder layer by a laser powder bed under continuous laser with the beam diameter of 50-130 mu m, the power of 200-350W, the scanning speed of 800-2000 mm/s and the scanning interval of 60-120 mu m, and naturally cooling the formed piece to obtain the precipitation-strengthened nickel-based superalloy part.

Technical Field

The invention relates to the technical field of material preparation, in particular to a laser powder bed fusion forming method for coarsening precipitation strengthening nickel-based high-temperature alloy grains.

Background

In the forming process, a computer system controls laser high-energy beam to selectively melt metal powder, rapid forming of complex parts is realized by a layer-by-layer accumulation method, the method has the advantages of material saving, high size precision and the like, and the forming requirements of partial metal structural materials (such as nickel-based high-temperature alloy, aluminum alloy, titanium alloy, stainless steel and the like) are met at present.

Under the conditions of high temperature (above 2000 ℃), micro-molten pool (30-120 mu m) and ultra-fast cooling solidification (solidification rate reaching 5m/s) generated in the process of laser powder bed melt forming, the material in the laser powder bed melt forming has relatively fine grain structure. For metallic structural materials used at normal temperature, refining grains and increasing grain boundaries can strengthen the performance of the material.

However, in the case of high temperature alloys with high service temperature, the grain boundary rather becomes a weak part of the material strength, so that it is difficult to meet the requirements in use for the manufacture of complex precision components of precipitation strengthening casting high temperature alloys which are widely used in the fields of aerospace, energy industry and the like and can work at higher temperature.

CN111500898A discloses a nickel-based superalloy, a manufacturing method, a component and an application thereof, and specifically comprises the following steps: the nickel-based high-temperature alloy is prepared by 3D printing the following raw materials; the raw materials comprise (by mass percent): less than or equal to 0.3% of C, less than 5% of Co, 13-15% of W, 20-24% of Cr, 1-3% of Mo, 0.2-0.5% of Al, less than 0.1% of Ti, less than 3% of Fe, less than 0.015% of B, 0.001-0.004% of La, 0.01-0.2% of Mn, 0.02-0.2% of Si, and the balance of Ni; the average carbide size in the structure is 150-200 nm, the carbide size distribution is 50 nm-4 mu m, the alloy has no cracks on the surface and inside and high-temperature strength, and the general applicability is not realized by adjusting the composition of the nickel-based high-temperature alloy powder.

Therefore, there is a need to develop a method for preparing a high temperature alloy with general applicability, which can be used at high temperature.

Disclosure of Invention

In view of the problems in the prior art, the invention provides a laser powder bed fusion forming method for coarsening precipitation-strengthened nickel-based superalloy grains, which can realize the effect of coarsening the grains and further remarkably improve the high-temperature mechanical property of the precipitation-strengthened nickel-based superalloy through the interaction of rare earth element oxide particles and precipitation-strengthened nickel-based superalloy powder.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a laser powder bed fusion forming method for coarsening precipitation strengthening nickel-based superalloy crystal grains, which comprises the following steps: mixing rare earth element oxide particles and precipitation-strengthened nickel-based superalloy powder, and performing laser powder bed fusion forming by using continuous laser to obtain a formed piece.

The invention aims to coarsen crystal grains and provides a preparation method of a high-temperature-resistant forming piece, wherein rare earth element oxide particles and precipitation-strengthened nickel-based superalloy powder interact under the action of continuous laser, and elements such as aluminum and the like in the rare earth element oxide particles and the precipitation-strengthened nickel-based superalloy powder form a heat-resistant material with a low high-temperature heat conductivity coefficient, so that the diffusion coefficient in the rapid solidification process can be reduced, a local heat island is formed in a matrix, the cooling rate in a solidified melt is reduced, and the effect of coarsening the crystal grains is finally achieved; after the crystal grains are coarsened, the number of fragile crystal boundaries at high temperature can be reduced, and the mechanical property of a formed piece in a high-temperature environment is improved.

The precipitation strengthening nickel-based superalloy of the invention is an alloy which takes nickel as a main matrix element and generates strengthening effect by a solute atom segregation area in a supersaturated solid solution and/or particles desolventized from a saturated solid solution which are dispersed and distributed in the matrix.

The high temperature is not less than 600 ℃, and may be 600 ℃, 620 ℃, 630 ℃, 650 ℃, 680 ℃, 700 ℃, 720 ℃, 750 ℃, 800 ℃ or the like.

Preferably, the particle size D50 of the precipitation-strengthened nickel-base superalloy powder is 20 to 35 μm, and may be, for example, 20 μm, 22 μm, 24 μm, 25 μm, 27 μm, 29 μm, 30 μm, 32 μm, 34 μm, or 35 μm, but is not limited to the values listed, and other values not listed within this range are also applicable.

Preferably, the particle size of the precipitation-strengthened nickel-base superalloy powder is in the range of 15 to 53 μm, and may be, for example, 15 μm, 20 μm, 24 μm, 28 μm, 32 μm, 37 μm, 41 μm, 45 μm, 49 μm, 53 μm, or the like, but is not limited to the values listed, and other values not listed in this range are also applicable.

Preferably, the precipitation strengthened nickel-base superalloy is IN738LC precipitation strengthened nickel-base superalloy.

The IN738LC precipitation strengthening nickel-based high-temperature alloy is selected, when the alloy is applied to 3D printing, because the alloy needs quick cooling and quick heating, the IN738LC crystal grain is thin, IN the quick cooling and quick heating processes, the crystal grain boundary is more, and the crystal grain boundary is a weak part of the material strength.

Preferably, the IN738LC precipitation-strengthened superalloy comprises the following composition C IN mass fraction: 0.10-0.20%, Cr: 15.7-16.3%, Co: 8.0-9.0%, W: 2.4-2.8%, Mo: 1.5-2.0%, Al: 3.2-3.7%, Ti: 3.0-3.5%, Fe: less than or equal to 0.5 percent, Nb: 0.6 to 1.1%, Ta: 1.5-2.0%, B: 0.005-0.015%, Zr: 0.05-0.15%, impurity elements: less than or equal to 0.55 percent, and the balance being nickel.

The IN738LC precipitation-strengthened superalloy of the present invention may have a C content of 0.10 to 0.20%, for example, 0.10%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, or 0.20%, but is not limited to the above-mentioned values, and other values not shown IN this range are also applicable.

The Cr content is 15.7 to 16.3%, and may be, for example, 15.7%, 15.8%, 15.9%, 16%, 16.1%, 16.2%, 16.3%, or the like, but is not limited to the values listed, and other values not listed in the range are also applicable.

The Co content is 8.0 to 9.0%, and may be, for example, 8.0%, 8.2%, 8.3%, 8.4%, 8.5%, 8.6%, 8.7%, 8.8%, 8.9%, or 9.0%, but is not limited to the above-mentioned values, and other values not listed in this range are also applicable.

The W content is 2.4 to 2.8%, and may be, for example, 2.4%, 2.45%, 2.49%, 2.54%, 2.58%, 2.63%, 2.67%, 2.72%, 2.76%, or 2.8%, but is not limited to the above-mentioned values, and other values not listed in the above range are also applicable.

The Mo content is 1.5 to 2.0%, and may be, for example, 1.5%, 1.56%, 1.62%, 1.67%, 1.73%, 1.78%, 1.84%, 1.89%, 1.95%, or 2.0%, but is not limited to the above-mentioned values, and other values not listed in this range are also applicable.

The Al content is 3.2 to 3.7%, and may be, for example, 3.2%, 3.26%, 3.32%, 3.37%, 3.43%, 3.48%, 3.54%, 3.59%, 3.65%, or 3.7%, but is not limited to the above-mentioned values, and other values not listed in the above range are also applicable.

The Ti content is 3.0 to 3.5%, and may be, for example, 3.0%, 3.06%, 3.12%, 3.17%, 3.23%, 3.28%, 3.34%, 3.39%, 3.45%, or 3.5%, but is not limited to the above-mentioned values, and other values not listed in the above range are also applicable.

The Fe content is 0.5% or less, and may be, for example, 0.1%, 0.15%, 0.19%, 0.24%, 0.28%, 0.33%, 0.37%, 0.42%, 0.46%, or 0.5%, but is not limited to the values listed, and other values not listed in the range are also applicable.

The Nb content is 0.6 to 1.1%, and may be, for example, 0.6%, 0.66%, 0.72%, 0.77%, 0.83%, 0.88%, 0.94%, 0.99%, 1.05%, or 1.1%, but is not limited to the above-mentioned values, and other values not listed in this range are also applicable.

The Ta content is 1.5 to 2.0%, and may be, for example, 1.5%, 1.56%, 1.62%, 1.67%, 1.73%, 1.78%, 1.84%, 1.89%, 1.95%, or 2.0%, but is not limited to the above-mentioned values, and other values not listed in the above range are also applicable.

The B content is 0.005 to 0.015%, and for example, 0.005%, 0.007%, 0.008%, 0.009%, 0.01%, 0.011%, 0.012%, 0.013%, 0.014%, or 0.015% may be used, but not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.

The Zr content is 0.05 to 0.15%, and may be, for example, 0.05%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, or 0.15%, but is not limited to the above-mentioned values, and other values not listed in the above range are also applicable.

The content of the impurity element is not more than 0.55%, and may be, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, or 0.55%, etc., but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.

Preferably, the mass ratio of the precipitation-strengthened nickel-base superalloy powder to the rare earth oxide particles is 50 to 5000:1, for example, 50:1, 600:1, 1000:1, 1150:1, 1700:1, 2250:1, 2800:1, 3000:1, 3350:1, 3900:1, 4450:1, or 5000:1, but not limited thereto, and other values not listed in this range are also applicable, preferably 1000 to 3000: 1.

According to the invention, the mass ratio of the precipitation-strengthened nickel-based high-temperature alloy powder to the rare earth element oxide particles is controlled within the range of 50-5000: 1, so that the interaction between the precipitation-strengthened nickel-based high-temperature alloy powder and the rare earth element oxide particles is facilitated, especially when the ratio is within the range of 1000-3000: 1, aluminum in the precipitation-strengthened nickel-based high-temperature alloy powder can fully react with the rare earth element oxide particles to form a heat-resistant material, and the effect of coarsening crystal grains is further improved.

Preferably, the rare earth element oxide particles are yttrium oxide particles.

The yttrium oxide particles interact with the precipitation strengthening nickel-based superalloy powder under the action of continuous laser to generate Y which is uniformly dispersed in a matrix₄Al₂O₉And (3) granules. Y is₄Al₂O₉Is a natural heat-resistant material and has a low high-temperature heat conductivity coefficient, so that the heat diffusion coefficient in the rapid solidification process can be reduced, a local heat island is formed in the melt, the cooling rate in the solidified melt is reduced, and the crystal grains can be coarsened to several degreesAlmost twice the size. By coarsening the crystal grains, the number of fragile crystal boundaries at high temperature is reduced, and the high-temperature mechanical property of the precipitation-strengthened nickel-based high-temperature alloy is obviously improved.

The rare earth oxide particles preferably have a particle size of 40 to 200nm, for example, 40nm, 58nm, 60nm, 76nm, 94nm, 112nm, 129nm, 147nm, 150nm, 165nm, 183nm, or 200nm, but not limited to the above-mentioned values, and other values not listed in this range are also applicable, and preferably 60 to 150 nm.

When the particle size of the rare earth element oxide particles is within the preferable range of 60-150 nm, the rare earth element oxide particles are more favorably dispersed on one hand, and are more favorably reasonably matched with the particle size of the nickel-based high-temperature alloy powder on the other hand, so that the powder mixing process is more uniform and sufficient.

Preferably, the beam diameter of the continuous laser is 50 to 130 μm, and may be, for example, 50 μm, 59 μm, 68 μm, 77 μm, 86 μm, 95 μm, 104 μm, 113 μm, 122 μm, 130 μm, or the like, but is not limited to the above-mentioned values, and other values not listed in the range are also applicable.

Preferably, the power of the continuous laser is 200-350W, such as 200W, 217W, 234W, 250W, 267W, 284W, 300W, 317W, 334W or 350W, but not limited to the recited values, and other values not recited in the range are also applicable.

Preferably, the scanning speed of the continuous laser is 800 to 2000mm/s, for example 800mm/s, 934mm/s, 1067mm/s, 1200mm/s, 1334mm/s, 1467mm/s, 1600mm/s, 1734mm/s, 1867mm/s or 2000mm/s, etc., but is not limited to the values listed, and other values not listed in this range are equally applicable.

Preferably, the scanning pitch of the continuous laser is 60 to 120 μm, and may be, for example, 60 μm, 67 μm, 74 μm, 80 μm, 87 μm, 94 μm, 100 μm, 107 μm, 114 μm or 120 μm, but is not limited to the values listed, and other values not listed in this range are also applicable.

Preferably, the device for laser powder bed fusion forming is a laser powder bed fusion device.

Preferably, the mixed rare earth element oxide particles and the precipitation-strengthened nickel-base superalloy powder are placed in a forming cavity of laser powder bed melting equipment to form a powder layer, and then the laser powder bed melting forming is carried out.

The thickness of the powder layer is preferably 30 to 50 μm, and may be, for example, 30 μm, 33 μm, 35 μm, 37 μm, 39 μm, 42 μm, 44 μm, 46 μm, 48 μm or 50 μm, but is not limited to the values listed above, and other values not listed above in this range are also applicable.

Preferably, the forming chamber of the laser powder bed fusing apparatus is evacuated prior to forming the powder layer.

Preferably, the degree of vacuum after evacuation is 3 to 10Pa, and may be, for example, 3Pa, 3.8Pa, 4.6Pa, 5.4Pa, 6.2Pa, 6.9Pa, 7.7Pa, 8.5Pa, 9.3Pa or 10Pa, but is not limited to the values listed above, and other values not listed in this range are also applicable.

Preferably, the powder layer is preheated before the laser powder bed is melt-formed.

Preferably, the temperature of the preheating is not less than 100 ℃, for example, 100 ℃, 123 ℃, 145 ℃, 167 ℃, 189 ℃, 212 ℃, 234 ℃, 256 ℃, 278 ℃, or 300 ℃, etc., but not limited to the recited values, and other values not recited in the range are also applicable.

Preferably, the laser powder bed fusion forming is performed in a protective atmosphere.

Preferably, the protective atmosphere comprises argon and/or helium.

Preferably, the formed piece after the laser powder bed melting forming is cooled to obtain the precipitation-strengthened nickel-base superalloy part.

Preferably, the cooling comprises natural cooling.

As a preferable technical scheme of the invention, the method comprises the following steps:

(1) vacuumizing a forming cavity of laser powder bed melting equipment to 3-10 Pa, and filling protective atmosphere;

(2) mixing precipitation-strengthened nickel-based high-temperature alloy powder with the particle size range of 15-53 mu m and the particle size D50 of 20-35 mu m and yttrium oxide particles with the particle size of 40-200 nm according to the mass ratio of 50-5000: 1, placing the mixture in a forming cavity of laser powder bed melting equipment under a protective atmosphere to form a powder layer with the particle size of 30-50 mu m, and preheating the powder layer until the temperature is more than or equal to 100 ℃;

(3) and melting and forming the powder layer by a laser powder bed under continuous laser with the beam diameter of 50-130 mu m, the power of 200-350W, the scanning speed of 800-2000 mm/s and the scanning interval of 60-120 mu m, and naturally cooling the formed piece to obtain the precipitation-strengthened nickel-based superalloy part.

Compared with the prior art, the invention has at least the following beneficial effects:

(1) according to the laser powder bed fusion forming method for coarsening precipitation-strengthened nickel-base superalloy crystal grains, rare earth element oxide particles are added, so that the crystal grains can be coarsened remarkably, the size of the precipitation-strengthened nickel-base superalloy crystal grains is increased to be larger than or equal to 55 mu m, and is larger than or equal to 80 mu m under the optimal condition;

(2) the laser powder bed fusion forming method for coarsening precipitation strengthening nickel-based superalloy grains provided by the invention can aim at most precipitation strengthening nickel-based superalloys, and has the advantages of high universality and strong repeatability;

(3) the high-temperature tensile strength of a formed part prepared by the laser powder bed fusion forming method of the coarsening precipitation strengthening nickel-based superalloy crystal grain is improved to be more than 720MPa, the high-temperature tensile strength of the formed part is improved to be more than 750MPa under better conditions, the high-temperature yield strength can reach 632.88MPa, and the mechanical property is obviously improved.

Drawings

FIG. 1 is an electron back-scattered diffraction pattern of precipitation-strengthened nickel-base superalloy components prepared according to example 1 and comparative example 1 of the present invention.

FIG. 2 is a tensile curve of a tensile test of precipitation strengthened nickel-base superalloy parts according to example 1 of the present invention and comparative example 1.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

The present invention is described in further detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.

First, an embodiment

Example 1

The embodiment provides a laser powder bed fusion forming method for coarsening precipitation strengthening nickel-base superalloy crystal grains, which comprises the following steps:

(1) vacuumizing a forming cavity of laser powder bed melting equipment to 5Pa, and filling argon with the purity of 99.99 wt%;

(2) mixing IN738LC precipitation strengthening nickel-based superalloy powder with the particle size range of 15-53 mu m and the particle size D50 of 30.1 mu m and yttrium oxide particles with the particle size of 80-130 nm according to the mass ratio of 2000:1, placing the mixture IN a forming cavity of laser powder bed melting equipment IN an argon atmosphere to form a 30 mu m powder layer, and preheating the powder layer to the temperature of 200 ℃;

(3) and melting and forming the powder layer by a laser powder bed under continuous laser with the beam diameter of 80 mu m, the power of 290W, the scanning speed of 1200mm/s and the scanning interval of 90 mu m, and naturally cooling the formed piece to obtain the precipitation-strengthened nickel-based superalloy part.

The precipitation strengthening high-temperature alloy powder with the material IN738LC comprises the following components IN percentage by mass: 0.12%, Cr: 15.82%, Co: 8.32%, W: 2.58%, Mo: 1.82%, Al: 3.50%, Ti: 3.48%, Nb: 0.88%, Ta: 1.78%, B: 0.01%, Zr: 0.06%, impurity elements: less than or equal to 0.55 percent, and the balance being nickel.

Example 2

The embodiment provides a laser powder bed fusion forming method for coarsening precipitation strengthening nickel-base superalloy crystal grains, which comprises the following steps:

(1) vacuumizing a forming cavity of laser powder bed melting equipment to 4Pa, and filling argon with the purity of 99.99 wt%;

(2) mixing IN738LC precipitation strengthening nickel-based superalloy powder with the particle size range of 15-50 mu m and the particle size D50 of 21.3 mu m and yttrium oxide particles with the particle size of 40-100 nm according to the mass ratio of 50:1, placing the mixture IN a forming cavity of laser powder bed melting equipment IN an argon atmosphere to form a 50 mu m powder layer, and preheating the powder layer to the temperature of 100 ℃;

(3) and melting and forming the powder layer by a laser powder bed under continuous laser with the beam diameter of 85 micrometers, the power of 350W, the scanning speed of 2000mm/s and the scanning interval of 120 micrometers, and naturally cooling the formed part to obtain the precipitation-strengthened nickel-based superalloy part.

The precipitation strengthening high-temperature alloy powder with the material IN738LC comprises the following components IN percentage by mass: 0.12%, Cr: 15.82%, Co: 8.32%, W: 2.58%, Mo: 1.82%, Al: 3.50%, Ti: 3.48%, Nb: 0.88%, Ta: 1.78%, B: 0.01%, Zr: 0.06%, impurity elements: less than or equal to 0.55 percent, and the balance being nickel.

Example 3

The embodiment provides a laser powder bed fusion forming method for coarsening precipitation strengthening nickel-base superalloy crystal grains, which comprises the following steps:

(1) vacuumizing a forming cavity of laser powder bed melting equipment to 6Pa, and filling helium with the purity of 99.99 wt%;

(2) mixing IN738LC precipitation strengthening nickel-based superalloy powder with the particle size range of 20-45 mu m and the particle size D50 of 33.2 mu m with yttrium oxide particles with the particle size of 120-200 nm according to the mass ratio of 4500:1, placing the mixture IN a forming cavity of laser powder bed melting equipment IN a helium atmosphere to form a 45 mu m powder layer, and preheating the powder layer to the temperature of 170 ℃;

(3) and melting and forming the powder layer by a laser powder bed under continuous laser with the beam diameter of 80 mu m, the power of 200W, the scanning speed of 800mm/s and the scanning interval of 60 mu m, and naturally cooling the formed piece to obtain the precipitation-strengthened nickel-based superalloy part.

The precipitation strengthening high-temperature alloy powder with the material IN738LC comprises the following components IN percentage by mass: 0.12%, Cr: 15.82%, Co: 8.32%, W: 2.58%, Mo: 1.82%, Al: 3.50%, Ti: 3.48%, Nb: 0.88%, Ta: 1.78%, B: 0.01%, Zr: 0.06%, impurity elements: less than or equal to 0.55 percent, and the balance being nickel.

Example 4

This example provides a laser powder bed fusion forming method of coarsening precipitation strengthened nickel-base superalloy grains, which is the same as example 1 except that the "mass ratio of 2000: 1" in step (2) is replaced by "mass ratio of 4000: 1".

Example 5

This example provides a laser powder bed fusion forming method of coarsening precipitation strengthened nickel-base superalloy grains, which is the same as example 1 except that the "mass ratio of 2000: 1" in step (2) is replaced by the "mass ratio of 800: 1".

Example 6

The embodiment provides a laser powder bed fusion forming method for coarsening precipitation-strengthened nickel-based superalloy grains, which is the same as that in the embodiment 1 except that the yttrium oxide particles with the grain size of 80-130 nm in the step (2) are replaced by the yttrium oxide particles with the grain size of 20-50 nm.

Example 7

The embodiment provides a laser powder bed fusion forming method for coarsening precipitation-strengthened nickel-based superalloy grains, which is the same as that in the embodiment 1 except that the yttrium oxide grains with the grain size of 80-130 nm in the step (2) are replaced by the yttrium oxide grains with the grain size of 160-200 nm.

Second, comparative example

Comparative example 1

The comparative example provides a laser powder bed fusion forming method for coarsening precipitation-strengthened nickel-base superalloy grains, which is the same as that in example 1 except that no yttrium oxide particles are added in the step (2).

Third, test and results

The test method comprises the following steps: and (3) carrying out a standard heat treatment system on the printed parts, namely carrying out solution treatment at 1120 ℃ for 2h, then carrying out air cooling, carrying out aging treatment at 850 ℃ for 24h, then carrying out air cooling, and testing the precipitation-strengthened nickel-based high-temperature alloy parts. The precipitation-strengthened nickel-base superalloy parts prepared in example 1 and comparative example 1 were mechanically polished and then placed on a Buehler VibroMet vibratory polisher for vibratory polishing for 2 hours, and then subjected to a mapping test using an EDAS Digiview4 electron backscatter probe equipped with a ZEISS Merlin scanning Electron microscope at a voltage of 20kV and a current of 5nA, as shown in FIG. 1.

FIG. 1 (a) shows the precipitation strengthened nickel-base superalloy component obtained in comparative example 1, FIG. 1 (b) shows the precipitation strengthened nickel-base superalloy component obtained in example 1, and it can be seen from FIG. 1 and calculations that the grain size of the precipitation strengthened nickel-base superalloy component obtained by the method described in example 1 is up to 96.34 μm from 54.28 μm using comparative example 1.

Using example 1 and comparative example 1 as examples, the precipitation-strengthened nickel-base superalloy components prepared therefrom were subjected to a high temperature tensile test at 850 deg.C, a temperature of 850 deg.C, a strain rate of 0.01mm/mm/min, and a ZJSY RDL100 tester, and the results are shown in FIG. 2.

As can be seen from FIG. 2 and the calculations, the high temperature tensile strength of the precipitation-strengthened nickel-base superalloy parts prepared by the method of example 1 is increased from 713.66MPa in comparative example 1 to 773.21MPa, and the high temperature yield strength is increased from 614.72MPa in comparative example 1 to 632.88 MPa.

The test results of the two are compared and calculated, and the formed part prepared by the method has no crack defects compared with a continuous laser formed part.

The test results of the above examples and comparative examples are shown in table 1.

TABLE 1

From table 1, the following points can be seen:

(1) it can be seen from the comprehensive examples 1 to 7 that the precipitation-strengthened nickel-based superalloy part prepared by the laser powder bed fusion forming method of the precipitation-strengthened nickel-based superalloy crystal grain provided by the invention has high-temperature tensile strength and crystal grain size, wherein the high-temperature tensile strength is greater than or equal to 720MPa, the high-temperature tensile strength is greater than or equal to 750MPa under a better condition, the crystal grain size is greater than or equal to 55 microns, the high-temperature tensile strength is greater than or equal to 80 microns under a better condition, the number of fragile crystal boundaries at high temperature is reduced, and the high-temperature mechanical property of the precipitation-strengthened nickel;

(2) it can be seen from the combination of examples 1, 4 to 5 and comparative example 1 that the mass ratio of the precipitation-strengthened nickel-based superalloy powder to the yttrium oxide particles in example 1 is 2000:1, which is 4000:1 and 800:1 respectively compared with examples 4 to 5, in comparative example 1 in which no yttrium oxide particles were added, the high-temperature tensile strength in example 1 was 773.21MPa, the crystal grain size was 96.34. mu.m, in examples 4 to 5, the high-temperature tensile strengths were 721.46MPa and 732.65MPa, respectively, and the crystal grain sizes were 59.69 μm and 64.16 μm, respectively, in comparative example 1, the high-temperature tensile strength was only 713.66MPa, the grain size was only 54.28. mu.m, therefore, the invention greatly improves the tensile strength and the grain size of the precipitation strengthening nickel-based high-temperature alloy by adding the yttrium oxide particles, the tensile strength and the grain size of the precipitation-strengthened nickel-base high-temperature alloy are further improved by selecting the proportion of the yttrium oxide particles;

(3) it can be seen from the combination of example 1 and examples 6 to 7 that the particle size of the yttrium oxide particles in example 1 is 80 to 130nm, the high-temperature tensile strength in example 1 is 773.21MPa, and the grain size is 96.34 μm, compared with the particle sizes of the yttrium oxide particles in examples 6 to 7 of 20 to 50nm and 160 to 200nm, respectively, while the high-temperature tensile strengths in examples 6 and 7 of 751.32MPa and 745.68MPa, and the grain sizes of 78.42 μm and 69.86 μm, respectively, thereby indicating that the tensile strength and the grain size of the precipitation-strengthened nickel-based superalloy are better improved by controlling the particle size of the yttrium oxide particles within a specific range.

In summary, according to the laser powder bed fusion forming method for coarsening precipitation-strengthened nickel-based superalloy grains provided by the invention, rare earth element oxide particles are doped into the precipitation-strengthened nickel-based superalloy powder before continuous laser powder bed fusion forming, so that the effect of coarsening the grains is achieved, the grain size is not less than 55 μm, preferably not less than 80 μm, the number of fragile grain boundaries at high temperature is reduced, the high-temperature tensile strength is not less than 720MPa, preferably not less than 750MPa, and the high-temperature mechanical property of the precipitation-strengthened nickel-based superalloy is remarkably improved.

The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, additions of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.