CN114959331B - Method for preparing nickel-based single crystal superalloy based on coaxial powder feeding laser additive manufacturing - Google Patents
Method for preparing nickel-based single crystal superalloy based on coaxial powder feeding laser additive manufacturing Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/0433—Nickel- or cobalt-based alloys
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
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- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/60—Treatment of workpieces or articles after build-up
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y40/00—Auxiliary operations or equipment, e.g. for material handling
- B33Y40/20—Post-treatment, e.g. curing, coating or polishing
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C19/03—Alloys based on nickel or cobalt based on nickel
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- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
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- B22F10/64—Treatment of workpieces or articles after build-up by thermal means
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Abstract
The invention discloses a method for preparing nickel-based single crystal superalloy based on coaxial powder feeding laser additive manufacturing, which specifically comprises the following steps: coaxially feeding powder to laser additive manufacturing on a wrought or cast nickel-based superalloy substrate, adding an auxiliary infrared light source to heat, and forming a sample with a certain size; performing second laser additive manufacturing by taking the side surface of the additive part with the directional solidification structure characteristics as a substrate to obtain an additive forming sample with basically consistent crystal orientation, and repeating the second step until a single crystal structure is obtained; the material is cut outside except the last material adding forming, and the rest is single crystal superalloy with completely consistent crystal orientation. The beneficial effects of the invention are as follows: the provided monocrystal preparation method utilizes the characteristics of directional heat dissipation and directional growth of laser additive manufacturing to realize the transition from random orientation to directional orientation to monocrystal, and has the characteristic of high efficiency compared with the technologies of a crystal selection method, a seed crystal method and the like.
Description
Technical Field
The invention relates to the field of laser additive manufacturing, in particular to a method for preparing nickel-based single crystal superalloy based on coaxial powder feeding laser additive manufacturing.
Background
As a method for producing a single crystal, a seed crystal method, a seed crystal-adding method, and the like are known. However, at present, a method for performing multiple crystal selection by utilizing the epitaxial growth characteristic of the nickel-based superalloy based on the laser additive manufacturing technology does not exist.
The single crystal superalloy is mainly used for manufacturing aero-engine and gas turbine hot end turbine blades, and has good high temperature strength, oxidation resistance, corrosion resistance, fatigue resistance, creep resistance, fracture performance and tissue stability. The temperature bearing capacity is a key technical index for improving the performance, efficiency and reliability of the engine.
In developed countries in Europe and America, research and development work of single crystal superalloy is carried out early and the technical maturity is high, but the research and development of single crystal superalloy and the research and development of single crystal blade are always very important. The performance of single crystal engine blades is excellent, but the material and manufacturing cost of single crystal blades is up to tens of thousands dollars, and the service life is limited by defects such as thermal fatigue crack, tip corrosion, surface wear, hot corrosion and the like. Replacement of single crystal blades has largely affected the operating costs of modern aeroengines and gas turbines.
At present, the advanced aeroengine blade material is mainly made of directional solidification casting nickel-based single crystal superalloy with excellent high-temperature mechanical property, but because the directional solidification and the single crystal blade are complex in appearance and are of complex hollow air-cooled structures, the defects of off-crystal, mixed crystal, small-angle grain boundaries and the like frequently occur in the manufacturing process, the appearance of the mixed crystal grain boundaries can influence the integrity of dendrite crystals, the mechanical property of the single crystal alloy is reduced, and the qualification rate of the single crystal blade is reduced. The mechanical properties of the nickel-based single crystal superalloy have significant anisotropy, which has the advantage of ensuring that the best performance is obtained in the stress direction, but the deviation of crystal orientation can seriously affect the high temperature mechanical properties of the single crystal blade.
The key to single crystal blade fabrication is how to avoid the creation of impurity crystal defects and to ensure the integrity of the single crystal structure. The crystal selection process can have important influence on the single crystal orientation and the formation of single crystal defects, and finally acts on the mechanical properties of the alloy. The scholars find that the equiaxed crystal structure gradually changes to the directional structure along with the increase of the distance from the surface of the forged substrate in the laser additive manufacturing process, and the equiaxed crystal structure completely changes to the directional structure after reaching a certain height, which shows that the direct preparation of the single crystal superalloy by utilizing the laser additive manufacturing technology is feasible.
Disclosure of Invention
Aiming at the problem that mixed crystals are easy to exist in the process of preparing the nickel-base single crystal superalloy by the current laser additive manufacturing, the invention discloses a method for preparing the nickel-base single crystal superalloy by the coaxial powder feeding laser additive manufacturing.
The invention adopts the following technical scheme: the method for preparing the nickel-based single crystal superalloy based on coaxial powder feeding laser additive manufacturing is characterized by comprising the following four steps:
firstly, manufacturing nickel-based superalloy on a forged or cast alloy substrate by adopting coaxial powder feeding laser additive; the proportion of dendrites with consistent orientation in the directional solidification structure is 70 percent;
secondly, selecting crystals, carrying out stress relief annealing on the material-increasing piece sample in the first step, milling the side surface of the material-increasing part until the surface is flat, and carrying out a second-step laser material-increasing process by taking the material-increasing part sample as a substrate and adopting the same coaxial powder-feeding laser material-increasing manufacturing process parameters as the first step; the proportion of dendrites with consistent orientation in the directional solidification structure is 95 percent;
thirdly, repeating the crystal selection, and repeating the crystal selection process of the second step by taking the material-increasing piece sample obtained after the crystal selection of the second step as a substrate; after the third step of crystal selection, the proportion of dendrites with consistent orientation in the obtained material-increasing region tissue is 100%, and all the monocrystal tissues with consistent crystal orientation are obtained;
and fourthly, cutting and cutting off part of the substrate by a linear cutting mode, carrying out the same stress relief annealing treatment in the second step again, and obtaining the rest part of the single crystal superalloy sample.
Further, the first step of manufacturing the nickel-based superalloy on the forged or cast alloy substrate by adopting coaxial powder feeding laser additive specifically comprises the following steps:
(1) Forming a sample with a certain size on a forged or cast alloy substrate by adopting a multilayer multi-channel unidirectional linear deposition mode laser material increase;
(2) The laser heat input process is high temperature gradient and high solidification speed, and the tissue of the material adding area is a dendritic crystal tissue which is directionally solidified;
(3) The heat dissipation conditions in the coaxial powder feeding process are limited, the peripheral surfaces of the additive piece samples are heated by using auxiliary infrared light sources, the heat dissipation in the horizontal direction of a molten pool is reduced, only the substrate is used for dissipating heat downwards, so that the heat dissipation direction is vertical, and dendrites preferentially grow along the heat dissipation direction;
(4) The proportion of dendrites with consistent orientation is increased to 70%.
Further, in the first step, the average grain size of the equiaxed crystal is 10-30 mu m, and the grain width of the columnar crystal structure obtained by the coaxial powder feeding laser additive manufacturing is 200-500 mu m; in the second step and the third step, the widths of columnar crystal grains are gradually increased, and finally, a single crystal structure is obtained.
Further, in the first step and the second step, the peripheral surface of the additive piece sample is heated by an auxiliary infrared light source in the coaxial powder feeding process, the heat dissipation of a molten pool in the horizontal direction is reduced, the dendrite structure with more consistent growth direction is further obtained, the optical radiation is adopted for non-contact heating, the metallurgical characteristic of the micro molten pool manufactured by additive is brought into play, the working temperature range of the auxiliary infrared light source is 800-1000 ℃, the heating power is 20-30 KW, the heating range can reach 5-10 times of the size of the molten pool, the heating depth can reach 0.4-1 mm, the molten pool is ensured to have no temperature gradient in the horizontal direction, and the heat is only diffused downwards through a substrate.
Further, the coaxial powder feeding laser additive manufacturing process comprises the following specific process parameters: the laser scanning strategy adopts a multilayer multichannel unidirectional straight line deposition mode, adopts a strategy with small energy input, large light spot size and large scanning speed, has the laser power of 800-1200W, the scanning speed of 10-20 mm/s, the light spot diameter of 3-5 mm, the lap joint rate of 20-30%, the single layer height of 0.05-0.1 mm, the powder feeding speed of 3-8 g/min and the powder carrying gas flow of 5-10L/min, and adopts argon gas for integral protection.
Furthermore, in the multilayer multichannel unidirectional linear deposition mode, each layer in each layer adopts a unidirectional and linear scanning mode in the additive manufacturing process, and compared with other known laser scanning strategies, the multilayer multichannel unidirectional linear deposition mode is adopted to more easily obtain a directional solidification structure with more consistent dendrite orientation.
Further, the coaxial powder feeding additive manufacturing alloy sample obtained in the second step is subjected to stress relief annealing, and the side surface of the additive part is taken as a substrate to carry out the second step; preferably, the stress relief annealing process is to heat to 300-500 ℃, more preferably 500 ℃; the temperature is kept for 4 to 8 hours, more preferably 4 hours.
Furthermore, the stress relief annealing process uses a muffle furnace or a vacuum heat treatment furnace with temperature control accuracy of +/-1 ℃ and capable of continuously working for a long time; heating to 500 ℃ at a heating rate of less than 100 ℃ per minute, preserving heat for 4 hours, and cooling to room temperature at a furnace cooling rate or a cooling rate of less than 100 ℃ per minute.
The beneficial effects of the invention are as follows: the provided monocrystal preparation method utilizes the characteristics of directional heat dissipation and directional growth of laser additive manufacturing to realize the transition from random orientation to directional orientation to monocrystal, and has the characteristic of high efficiency compared with the technologies of a crystal selection method, a seed crystal method and the like. The method for vertically selecting crystal for many times by infrared assistance disclosed by the invention can be used for preparing and obtaining the formed part with uniform dendritic crystal structure by more rapid and efficient.
Drawings
The invention is further described below with reference to the accompanying drawings:
FIG. 1 is a flow chart of a method for selecting crystals used in the present invention.
FIG. 2 is an isometric microstructure of a wrought GH4169 alloy base plate according to the invention.
FIG. 3 is a microstructure of the invention showing the first step dendrite growth direction on a wrought GH4169 alloy substrate.
FIG. 4 is a microstructure of dendrite growth direction of the second step perpendicular to the dendrite growth direction obtained in the first step.
Detailed Description
The invention provides a method for preparing a nickel-based single crystal superalloy based on coaxial powder feeding laser additive manufacturing, which can obtain a directional solidification structure with less mixed crystals and improve the qualification rate of the prepared single crystal.
The laser additive material has larger internal stress, and the invention preferably further comprises the steps of carrying out stress relief annealing on the nickel-base single crystal superalloy forming piece and cooling to room temperature. In the present invention, the cooling is preferably furnace cooling or air cooling.
The invention adopts the following technical scheme: the method for preparing the nickel-based single crystal superalloy based on coaxial powder feeding laser additive manufacturing is characterized by comprising the following four steps:
firstly, manufacturing nickel-based superalloy on a forged or cast alloy substrate by adopting coaxial powder feeding laser additive; the proportion of dendrites with consistent orientation in the directional solidification structure is 70 percent;
secondly, selecting crystals, namely firstly carrying out stress relief annealing on the material-increasing piece sample in the first step, milling the side surface of the material-increasing part until the surface is flat, and carrying out a second-step laser material-increasing process by taking the material-increasing part sample as a substrate and adopting the same coaxial powder-feeding laser material-increasing manufacturing process parameters as the first step; the proportion of dendrites with consistent orientation in the directional solidification structure is 95 percent;
thirdly, repeating the crystal selection, and repeating the crystal selection process of the second step by taking the material-increasing piece sample obtained after the crystal selection of the second step as a substrate; after the third step of crystal selection, the proportion of dendrites with consistent orientation in the obtained material-increasing region tissue is 100%, and all the monocrystal tissues with consistent crystal orientation are obtained;
and fourthly, cutting and cutting off part of the substrate by a linear cutting mode, carrying out the same stress relief annealing treatment in the second step again, and obtaining the rest part of the single crystal superalloy sample.
In the first step, the specific process is to adopt a multilayer multichannel unidirectional linear deposition mode laser material-adding forming sample with certain size on the forged or cast alloy substrate, and the material-adding area structure is a directional solidification dendrite structure due to the characteristics of high temperature gradient, high solidification speed and the like in the laser heat input process. Meanwhile, the heat dissipation conditions in the coaxial powder feeding process are limited, the peripheral surfaces of the additive piece samples are heated by using auxiliary infrared light sources, the heat dissipation in the horizontal direction of a molten pool is reduced, and only the substrate is used for dissipating heat downwards, so that the heat dissipation can be ensured in the vertical direction, and dendrites can preferentially grow along the heat dissipation direction. Under the condition that an auxiliary infrared light source is not added in the coaxial powder feeding process to control the heat radiation direction, the proportion of dendrites with consistent orientation is only 50% -60%, and after the auxiliary infrared light source is added to control the heat radiation direction, the proportion of dendrites with consistent orientation is improved by about 10%, and reaches 70%. Although dendrites with certain directional solidification structure characteristics are obtained in the first step, as the forged or cast alloy substrate is in equiaxed crystal structure, the crystal orientations among the equiaxed crystals are different, so that the orientation difference of dendrites in the material adding area is increased when the equiaxed crystals are used as substrates for directional solidification and growth, the dendrites with larger proportion still exist in the structure, the proportion of dendrites with consistent orientation is only 70%, and the obtained directional solidification structure still does not reach the standard of single crystal structure.
In the first step, at present, the research on preparing nickel-based superalloy by coaxial powder feeding laser additive manufacturing is only aimed at forming content in the first step of the invention, and no case of controlling the growth direction of dendrites by heating the peripheral surface of an additive piece sample by using an auxiliary infrared light source exists, and no case of obtaining single crystal alloy by further selecting dendrite tissues with directional solidification characteristics. The proportion of dendrites with consistent orientation in the single crystal structure reaches 100% compared with the proportion of dendrites with consistent orientation in the directional solidification structure of 70%. The single crystal structure eliminates the transverse grain boundary, and the uniformity of the grain orientation ensures that the alloy has more excellent mechanical properties in a specific direction at high temperature. The traditional crystal selection method, seed crystal method and other technical efficiency are too low, so the invention obtains the single crystal alloy by selecting the crystal of the nickel-based superalloy manufactured by coaxial powder feeding laser additive, the cost is low, the efficiency is high, and the obtained single crystal structure has the same effect as the traditional method.
In the first step, there is an inconsistent orientation of dendrite orientation in the coaxially fed laser additive manufactured tissue, and the deviation behavior of this dendrite orientation is random and uncontrollable due to the complexity of microscopic growth conditions. The closer the distance to the substrate, the more disordered the direction of dendrite growth; in order to obtain a single crystal structure with more consistent orientation, the heat dissipation direction of a molten pool needs to be controlled, and the auxiliary infrared light source is added to the periphery of the material-increasing piece sample for heating in the coaxial powder feeding process, so that the proportion of dendrites with consistent orientation in the obtained structure is increased by 10 percent, but the proportion does not reach the standard of single crystal alloy production. The present invention thus provides for the second and third steps of the process of selecting crystals.
In the second step, the proportion of dendrites with consistent orientation in the substrate structure can reach 70%, compared with the direct laser additive manufacturing on the as-forged or as-cast equiaxed crystal alloy substrate, the dendrites have small orientation difference when growing on dendrites as substrates, namely the number of dendrites which undergo competitive growth is small, and meanwhile, the proportion of dendrites with consistent orientation in the obtained dendrite structure reaches 95% due to the addition of an auxiliary infrared light source for controlling the heat dissipation direction of a molten pool.
And in the third step, repeating the process of the second step to re-check the crystals. Finally, the invention obtains the single crystal structure with the completely consistent dendrite orientation through the re-crystallization process. The qualification rate of the single crystal obtained by the traditional techniques such as a crystal selection method, a seed crystal method and the like is 90 percent, the qualification rate of the single crystal obtained by the third step of repeated crystal selection is 100 percent, the time is reduced to 1/10 of that of the traditional method, the efficiency is improved, and the cost is saved.
The method for obtaining the nickel-base single crystal superalloy based on coaxial powder feeding laser additive manufacturing provided by the invention is described in detail below with reference to examples, but the method is not to be construed as limiting the scope of the invention.
Example 1
GH4169 single crystal superalloy based on coaxial powder feeding laser additive manufacturing
Grinding the part of the wrought nickel-base superalloy substrate with the alloy grade GH4169, which is required to be added with material, removing oxide skin, and cleaning the surface with alcohol or acetone; and fixing and clamping the nickel-based superalloy substrate on a fixture clamp with a cooling function. And adopting coaxial powder feeding laser material adding for multiple crystal selection to obtain a single crystal tissue with completely consistent crystal orientation.
As shown in figure 1, according to the single crystal preparation method based on coaxial powder feeding laser additive manufacturing, through a four-step crystal selection process, a single crystal structure with consistent orientation and 100% dendrite proportion is finally obtained. Wherein, the first step: the GH4169 alloy is manufactured by coaxially feeding powder to a polished and cleaned forged GH4169 alloy substrate by laser additive, and a multilayer multichannel unidirectional linear deposition mode is adopted, so that the orientations of equiaxed crystal grains are inconsistent in a region close to the substrate, the growth directions of columnar dendrites growing along the equiaxed crystal grain boundaries are different, a destabilization region in a certain region range exists, the average orientation difference among the grains in the destabilization region is larger, the defects of off-set crystals, mixed crystals, freckles, small-angle grain boundaries and the like frequently occur in the manufacturing process, the integrity of crystals is cut off due to the occurrence of the grain boundaries, the mechanical property of the single crystal alloy is obviously reduced, and at the moment, the additive part has directional tissue characteristics, but the growth directions of the dendrites are inconsistent, the dispersivity is great, and the proportion of dendrites with consistent orientations is only 70%. Grain competition growth with heat flow control is the primary reason for grain elimination selection during directional solidification, and therefore dendrites with consistent orientation eliminate dendrites from other orientations during competition growth. And a second step of: and carrying out stress relief annealing on the GH4169 alloy sample manufactured by the laser additive with the preliminary directional solidification structure obtained by the first step of forming, cutting the GH4169 alloy sample from the wrought superalloy substrate, milling the side surface of the sample formed by the first step of forming until the surface is flat, and carrying out the second step of laser additive forming by taking the additive part as the substrate. At this time, the proportion of dendrites aligned uniformly in the tissue was 95%. And a third step of: repeating the second step of crystal selection by taking the material adding part sample obtained after the second step of crystal selection as a substrate; after the third step of crystal selection, the proportion of dendrites with consistent orientation in the obtained material-increasing region tissue is 100%, and all the monocrystal tissues with consistent crystal orientation are obtained; and fourthly, cutting and cutting off part of the substrate by a linear cutting mode, carrying out the same stress relief annealing treatment in the second step again, and obtaining the rest part of the single crystal superalloy sample.
FIG. 2 is an isometric microstructure of a wrought GH4169 alloy base plate having an average equiaxed grain size of 10-30 μm.
FIG. 3 shows a first step of seeding on a wrought GH4169 alloy substrate, the substrate in the lower region being of equiaxed grain structure with varying grain orientations, the upper region being the first step of dendrite growth direction of the additive region, although having directional structure characteristics, the dendrite growth direction is not uniform, the dispersibility is very large, and the proportion of dendrites aligned is only 70%; the grain width of the columnar crystal structure obtained by the coaxial powder feeding laser additive manufacturing is 460 mu m. In the second step and the third step, the widths of columnar crystal grains are gradually increased, and finally, a single crystal structure is obtained.
Fig. 4 shows the growth direction of dendrite in the second step, in which the second step of dendrite selection is performed in the growth direction of dendrite in the first step, the sample of the GH4169 alloy manufactured by laser additive with preliminary directional solidification structure obtained by the first step of forming is cut from the substrate of the GH4169 alloy in the forged state, the side surface of the sample obtained by the first step of additive forming is milled until the surface is flat, and the additive part is used as the substrate for performing the second step of laser additive forming. At this time, the proportion of dendrites aligned uniformly in the tissue was 95%. After the repeated crystal selection process of the third step, the proportion of dendrites with consistent orientation in the structure is 100%, and it is considered that a single crystal structure with completely consistent dendrite orientation can be obtained.
Example 2
GH3625 single-crystal superalloy obtained based on coaxial powder feeding laser additive manufacturing
Grinding the part of the wrought nickel-based superalloy substrate with the alloy grade GH3625, which is required to be added with material, removing oxide scales, and cleaning the surface by using alcohol or acetone; and fixing and clamping the nickel-based superalloy substrate on a fixture clamp with a cooling function. And adopting coaxial powder feeding laser material adding for multiple crystal selection to obtain a single crystal tissue with completely consistent crystal orientation.
The bottom of the deposition zone is an equiaxed crystal with a width of about 8 μm, a closely aligned, directionally solidified columnar crystal structure is epitaxially grown along the deposition height, and generally contains a plurality of grains with different orientations which are continuously competing for growth.
And cutting the GH3625 alloy sample with the preliminary directional solidification structure obtained in the first step from the wrought superalloy substrate by adopting linear cutting to perform the second step of laser additive forming. Through the second and third steps of the crystal selection process, the proportion of dendrites with consistent orientation in the structure is 100%, and it can be considered that a single crystal structure with completely consistent crystal orientation is obtained.
The results of metallographic structure observation and scanning electron microscope observation of the GH3625 single-crystal superalloy sample obtained based on coaxial powder feeding laser additive manufacturing described in example 2 are similar to those of FIGS. 2-4, which shows that a single-crystal sample with completely consistent dendrite orientation can be obtained by the crystal selection method described in the invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (4)
1. The method for preparing the nickel-based single crystal superalloy based on coaxial powder feeding laser additive manufacturing is characterized by comprising the following four steps:
firstly, manufacturing nickel-based superalloy on a forged or cast alloy substrate by adopting coaxial powder feeding laser additive; the proportion of dendrites with consistent orientation in the directional solidification structure is 70 percent;
secondly, selecting crystals, carrying out stress relief annealing on the material-increasing piece sample in the first step, milling the side surface of the material-increasing part until the surface is flat, and carrying out a second-step laser material-increasing process by taking the material-increasing part sample as a substrate and adopting the same coaxial powder-feeding laser material-increasing manufacturing process parameters as the first step; the proportion of dendrites with consistent orientation in the directional solidification structure is 95 percent;
thirdly, repeating the crystal selection, and repeating the crystal selection process of the second step by taking the material-increasing piece sample obtained after the crystal selection of the second step as a substrate; after the third step of crystal selection, the proportion of dendrites with consistent orientation in the obtained material-increasing region tissue is 100%, and all the monocrystal tissues with consistent crystal orientation are obtained;
fourthly, cutting and cutting off part of the substrate linearly, and carrying out the same stress relief annealing treatment in the second step again, wherein the rest part is the required monocrystal superalloy sample;
in the first step, the average grain size of the equiaxed crystal is 10-30 mu m, and the grain width of columnar crystal structures obtained by coaxial powder feeding laser additive manufacturing is 200-500 mu m; in the second step and the third step, the widths of columnar crystal grains are gradually increased, and a single crystal structure is finally obtained;
in the first step and the second step, the peripheral surface of the additive part sample is heated by an auxiliary infrared light source in the coaxial powder feeding process, the heat dissipation of a molten pool in the horizontal direction is reduced, then a dendrite structure with more consistent growth direction is obtained, the optical radiation is adopted for non-contact heating, the metallurgical characteristics of a micro molten pool for additive manufacturing are brought into play, the working temperature range of the auxiliary infrared light source is 800-1000 ℃, the heating power is 20-30 KW, the heating range can reach 5-10 times of the size of the molten pool, the heating depth can reach 0.4-1 mm, the fact that the molten pool has no temperature gradient in the horizontal direction is ensured, and the heat only diffuses downwards through a substrate.
2. The method for preparing the nickel-based single crystal superalloy based on coaxial powder feeding laser additive manufacturing according to claim 1, wherein the method comprises the following steps:
the first step adopts coaxial powder feeding laser material adding to manufacture nickel-based superalloy on a forging state or casting state alloy baseplate specifically comprises the following steps:
(1) Forming a sample with a certain size on a forged or cast alloy substrate by adopting a multilayer multi-channel unidirectional linear deposition mode laser material increase;
(2) The laser heat input process is high temperature gradient and high solidification speed, and the tissue of the material adding area is a dendritic crystal tissue which is directionally solidified;
(3) The heat dissipation conditions in the coaxial powder feeding process are limited, the peripheral surfaces of the additive piece samples are heated by using auxiliary infrared light sources, the heat dissipation in the horizontal direction of a molten pool is reduced, only the substrate is used for dissipating heat downwards, so that the heat dissipation direction is vertical, and dendrites preferentially grow along the heat dissipation direction;
(4) The proportion of dendrites with consistent orientation is increased to 70%.
3. The method for preparing the nickel-based single crystal superalloy based on coaxial powder feeding laser additive manufacturing according to claim 1, wherein the method comprises the following steps:
the coaxial powder feeding laser additive manufacturing process comprises the following specific process parameters: the laser scanning strategy adopts a multilayer multichannel unidirectional straight line deposition mode, adopts a strategy with small energy input, large light spot size and large scanning speed, has the laser power of 800-1200W, the scanning speed of 10-20 mm/s, the light spot diameter of 3-5 mm, the lap joint rate of 20-30%, the single layer height of 0.05-0.1 mm, the powder feeding speed of 3-8 g/min and the powder carrying gas flow of 5-10L/min, and adopts argon gas for integral protection.
4. The method for preparing the nickel-based single crystal superalloy based on coaxial powder feeding laser additive manufacturing according to claim 2, wherein the method comprises the following steps:
in the multilayer multichannel unidirectional linear deposition mode, each layer in the additive manufacturing process adopts a unidirectional and linear scanning mode, and compared with other known laser scanning strategies, the multilayer multichannel unidirectional linear deposition mode is adopted to more easily obtain a directional solidification structure with more consistent dendrite orientation.
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| CN105108142A (en) * | 2015-06-18 | 2015-12-02 | 航星利华(北京)科技有限公司 | Method for manufacturing monocrystalline and directional solidified part through laser 3D printer |
| US11318553B2 (en) * | 2019-01-04 | 2022-05-03 | Raytheon Technologies Corporation | Additive manufacturing of laminated superalloys |
| GB202007591D0 (en) * | 2020-05-21 | 2020-07-08 | Renishaw Plc | Additive manufacturing methods and apparatus for forming objects from a nickel-based supperally in a layer-by-layer manner |
| CN112122617A (en) * | 2020-08-21 | 2020-12-25 | 苏州华普森激光科技有限公司 | Laser additive repair method for high-performance monocrystalline directional crystal turbine blade |
| CN214601945U (en) * | 2021-04-12 | 2021-11-05 | 南昌航空大学 | Nickel-based single crystal superalloy laser composite manufacturing auxiliary device with directional heat dissipation function |
| CN113458417B (en) * | 2021-06-29 | 2023-02-14 | 西北工业大学 | Preparation method for manufacturing nickel-based superalloy directional solidification structure through laser additive manufacturing |
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