CN114799204B - Method for reducing brittle Laves phase in laser additive manufacturing nickel-based high-temperature alloy and improving strong plasticity - Google Patents

Abstract

The invention discloses a method for reducing brittle Laves phase in laser additive manufacturing nickel-based superalloy and improving strong plasticity, which comprises the following steps: s1, wet mixing nano carbon powder and nickel-based high-temperature alloy powder, drying and cooling; s2, starting a laser additive manufacturing and forming test and obtaining process parameters of laser additive manufacturing and forming; and S3, performing a laser additive forming test to obtain a non-defective high-density sedimentary sample, and performing microstructure analysis and mechanical property test on the sedimentary sample. According to the invention, a small amount of carbon element is introduced into the nickel-based high-temperature alloy powder and technological parameters of laser additive forming manufacturing are regulated, so that the carbon element plays a role in reducing the content of a brittle Laves phase in the nickel-based high-temperature alloy, the formation of the brittle Laves phase with chain-shaped distribution among dendrites in a deposited sample is effectively avoided, the content of the brittle Laves phase is reduced, and the dispersion distribution of small-size carbides is controlled, so that the room-temperature mechanical property of the nickel-based high-temperature alloy manufactured by laser additive manufacturing is improved.

Description

A method for reducing brittle Laves phase in nickel-based superalloy manufactured by laser additive manufacturing and its improvement strong plastic method

technical field

The invention relates to the technical field of nickel-based superalloy preparation and laser additive manufacturing, in particular to a method for reducing brittle Laves phase and improving strong plasticity in nickel-based superalloy manufactured by laser additive manufacturing.

Background technique

Nickel-based superalloys are widely used in hot-end components such as aerospace engines and gas turbines because of their good high-temperature mechanical properties and excellent oxidation and corrosion resistance. At present, 30%-45% of the hot end parts of aero-engines and gas turbines are made of high-temperature alloys through forging and machining, resulting in a great waste of high-temperature alloys. In addition, superalloys are generally not easy to deform and difficult to process, which makes it more difficult to process superalloy parts with complex structures. In the actual design and manufacturing process of parts, we have to consider the existing processing technology limitations and sacrifice part of the structure. Functionality and lightweight characteristics have seriously restricted the innovative development of aero-engine and gas turbine technologies. Laser additive manufacturing technology, with its free-entity digital manufacturing features, and the advantages of no mold, short cycle time, high-performance integrated forming of complex components, etc., has gradually shown great potential in the manufacture of complex components in aerospace, power energy and other fields. application prospects.

However, affected by the composition of the superalloy and the characteristics of the laser additive manufacturing process, the microsegregation of alloying elements during the solidification process will lead to the formation of continuously distributed chain-like brittle phases between dendrites, such as Laves equivalence. The existence of brittle phase will seriously reduce the mechanical properties of the alloy. On the one hand, it will consume a large amount of solid solution strengthening and precipitation strengthening elements, reducing the strengthening effect; toughness of the alloy. Therefore, it is necessary to improve the mechanical properties of the alloy by reducing the continuous distribution of brittle phases in nickel-based superalloys through a suitable process. High-temperature solid solution heat treatment can fully dissolve the brittle phase, thereby improving the toughness of the alloy. However, this kind of treatment will cause recrystallization to reduce the dislocation density, resulting in a significant decrease in the yield strength of the alloy, which is not conducive to the improvement of the comprehensive mechanical properties of the alloy. .

Contents of the invention

The main purpose of the present invention is to solve the problem that the presence of brittle phases distributed in a continuous chain between dendrites in the deposit state sample of nickel-base superalloy produced by laser additive manufacturing in the prior art will lead to a decrease in the mechanical properties of the alloy, and the subsequent high-temperature solid solution treatment will Seriously reducing the yield strength of the alloy, which affects the strengthening and toughening effect of the alloy and other technical problems, proposed a method to reduce the brittle Laves phase and improve the strong plasticity in the nickel-based superalloy manufactured by laser additive manufacturing.

In a first aspect of the present invention, a method for reducing the brittle Laves phase and improving the strong plasticity in nickel-based superalloys manufactured by laser additive manufacturing is proposed, comprising the following steps:

S1. After wet mixing nano-carbon powder and nickel-based superalloy powder in absolute ethanol according to the mass ratio, dry and cool to obtain carbon-containing nickel-based superalloy powder;

S2. Put the carbon-containing nickel-based superalloy powder into the powder feeder, fill the laser additive manufacturing forming chamber with argon as an inert protective gas, and start the laser additive manufacturing forming test after the oxygen content in the forming chamber drops to 50ppm And get the process parameters of laser additive manufacturing;

S3. The carbon-containing nickel-based superalloy powder obtained in step S1 is subjected to a laser additive forming test according to the process parameters of laser additive manufacturing forming in step S2 to obtain a defect-free and high-density deposited sample. The microstructure analysis and mechanical property test were carried out to clarify the influence of the introduction of carbon on the volume fraction and distribution characteristics of the brittle Laves phase and the improvement of the strong plasticity of the alloy.

In some embodiments of the present invention, in step S1, the mass compounding ratio of nano-carbon powder and nickel-based superalloy powder is (0.5-4): (996-999.5), preferably (1-2): (998-999).

In some embodiments of the present invention, in step S1, the nano-carbon powder is selected from graphite powder with a particle size of 40-60 nm; the nickel-based superalloy powder is selected from solid-solution-strengthened nickel-based superalloys or precipitation-strengthened Nickel-based superalloy; the particle size of the nickel-based superalloy powder used in the coaxial powder feeding directed energy deposition process is 50-150 μm, and the particle size used in the selective laser melting process is 15-53 μm.

In some embodiments of the present invention, in step S1, the wet mixing is carried out by using a planetary ball mill in absolute ethanol. After -5 min, stop for 30 s and reverse for 3-5 min, wet mixing time is 3-6 h; the drying is drying in a vacuum oven, the drying temperature is 110-130 °C, and the drying time is 4 -6 h.

In some embodiments of the present invention, in step S2, the laser additive manufacturing shaping is selected from a coaxial powder feeding directed energy deposition process or a selective laser melting process.

In some embodiments of the present invention, in step S2, the laser type used in the coaxial powder-feeding directed energy deposition process is a _CO2 laser, a fiber laser or a semiconductor laser, and the optimized process parameters are: the laser power is 1000 -3000 W, the spot diameter is 2-5 mm, the scanning speed is 10-30 mm/s, the powder feeding volume is 8-20 g/min, the powder-carrying gas flow rate is 4-10 L/min, and the overlap rate is 40 %-60%, the lifting amount is 0.4-0.6mm; the energy distribution of the laser used is Gaussian distribution or bimodal distribution, and the protective gas and carrier powder are both argon gas during the forming process.

In some embodiments of the present invention, in step S2, the laser used in the selective laser melting process is a fiber laser, and the optimized process parameters are as follows: laser power is 180-300 W, spot diameter is 50-100 µm, scanning speed The scanning distance is 300-1200 mm/s, the scanning distance is 60-100 µm, the powder coating thickness is 30-50 µm, the laser used can be continuous laser or pulsed laser, and the wavelength is 1060 nm.

In some embodiments of the present invention, in step S3, when the coaxial powder-feeding directed energy deposition process is adopted for the laser additive manufacturing, the laser scanning mode in the layer is unidirectional scanning or reciprocating scanning, and the layer-to-layer The inter-laser scanning paths can be cross scanning or reciprocating scanning.

In some embodiments of the present invention, in step S3, when the laser additive manufacturing forming adopts the selective laser melting process, the scanning mode in the layer is unidirectional scanning or reciprocating scanning, and the interlayer rotation angle is 0°, 90° or Any of 67°.

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

The present invention introduces a small amount of carbon element into the nickel-based superalloy powder and regulates the process parameters of laser additive manufacturing, so that the carbon element can play the role of reducing the brittle Laves phase content in the nickel-based superalloy, effectively avoiding the deposition state of the sample. The formation of brittle Laves phases distributed in chains between dendrites reduces the content of brittle Laves phases, and at the same time controls the dispersion of small-sized carbides, and tests the mechanical properties of deposited samples to clarify that the introduction of carbon elements can improve the strength of alloys. The law of influence of plasticity can play a role in improving the room temperature mechanical properties of nickel-based superalloys manufactured by laser additive manufacturing.

Description of drawings

Figure 1 is an electron microscope photo of nickel-based superalloy powder manufactured by laser additive manufacturing in the present invention.

Fig. 2 is a microstructure diagram of the deposited nickel-based superalloy after adding 0.1% carbon element (mass percentage) in laser additive manufacturing in Example 1 of the present invention.

Fig. 3 is a microstructure diagram of nickel-based superalloy deposited after adding 0.2% carbon element (mass percentage) in laser additive manufacturing in Example 2 of the present invention.

Fig. 4 is a microstructure diagram of nickel-based superalloy deposited after adding 0.4% carbon element (mass percentage) in laser additive manufacturing in Example 3 of the present invention.

Fig. 5 is a photograph of the deposited state microstructure of a nickel-based superalloy without carbon elements added by laser additive manufacturing in Comparative Example 1 of the present invention.

Fig. 6 is a microstructure diagram of nickel-based superalloy deposited after adding 0.6% carbon element (mass percentage) in laser additive manufacturing in comparative example 2 of the present invention.

detailed description

The conception and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments, so as to fully understand the purpose, features and effects of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts belong to The protection scope of the present invention.

Test method for mechanical properties (yield strength, tensile strength, elongation) at room temperature: sampling tensile samples from deposited samples, the shape of the sample is plate-like, the gauge length is 20mm, and the width and thickness are 6mm and 6mm respectively. During the stretching process, the moving speed of the crossbeam of the stretching machine is 1mm/min. In order to accurately measure the elastic modulus and yield strength, an extensometer with a length of 10mm is used to measure the deformation of the sample during the stretching process. To calculate the engineering strain, the residual elongation stress σ _r0.2 is defined as the yield strength, the tensile strength is the stress value corresponding to the maximum test force during the specimen breaking process, and the elongation rate is the elongation rate after fracture. The specific measurement method is the specimen standard after fracture. The percentage of the elongation of the distance segment to the initial gauge length.

Example 1

A method for reducing the brittle Laves phase and improving the strong plasticity in nickel-based superalloys manufactured by laser additive manufacturing. Taking Inconel 625 nickel-based superalloy as an example, the alloy composition is 63.59 Ni-21.5 Cr-8.5Mo-3.5 Nb-2.0 Fe- 0.2 Ti-0.2 Al-0.5 Si-0.01 C (mass percentage), the addition of carbon in the alloy is 0.1% (mass percentage);

S1: Take 1g of graphite powder with a particle size of 50nm and 999g of spherical Inconel 625 alloy powder with a particle size of 50-150µm (as shown in Figure 1) into a stainless steel ball mill jar and add absolute ethanol, and put the ball mill jar into the planet Ball milling is carried out in a type ball mill. The ball milling process parameters are: speed 160r/min, forward rotation for 5 minutes, stop for 30 seconds, and then reverse for 5 minutes. The whole mixing process lasts for 4 hours; The can is dried in a vacuum drying oven, the drying temperature is set to 120 ° C, and the drying duration is 6 hours. After drying, it is placed in a vacuum environment and cooled to room temperature to obtain carbon-containing nickel-based superalloy powder;

S2: Put the powder dried in step S1 into the powder feeder, fill the forming chamber with argon as an inert protective gas, and start the forming test after the oxygen content in the forming chamber drops to 50ppm; after optimization The laser additive manufacturing process parameters are as follows: laser power 2000 W, spot diameter 5 mm, scanning speed 30 mm/s, powder feeding volume 15 g/min, powder airflow 8 L/min, lap rate 50%, the lift is 0.6 mm. Among them, the type of laser used is a fiber laser with a maximum output power of 10,000 W;

S3: The carbon-containing nickel-based superalloy powder obtained in step S1 is subjected to a block forming test according to the optimized process parameters in step S2. The laser scanning path between layers is cross-scanning, and the size of the formed sample is 80×10 ×20mm; the sample was cut along the deposition direction by wire cutting to prepare metallographic, and the surface of the sample was ground and polished with #80, #180, #400, #1000 and #2000 SiC sandpaper in sequence; in order to observe the block Macroscopic and microstructure of bulk samples, polished samples were chemically etched with etchant (6 mL HCl + 2 mL H2O + 1 g CrO ₃ ); using optical microscope (OM, LeicaMicrosystem DM-3000) and field emission scanning electron microscope (FE-SEM, HITACHI SU8010) to analyze the dendrite morphology and the distribution characteristics of the second phase, as shown in Figure 2: From Figure 2, it can be seen that compared with the reference group without adding carbon, the macrostructure is still It is a columnar dendrite, the content of the chain Laves phase continuously distributed among the dendrites is reduced, and the granular carbide is dispersedly distributed, indicating that the addition of trace carbon elements has played a role in inhibiting the chain Laves phase, which has brought great impact on the strengthening and toughening of the material. Favorable influence. The experimental data of yield strength, tensile strength and elongation of the prepared nickel-based superalloy manufactured by laser additive manufacturing are shown in Table 1.

Example 2

A method for reducing the brittle Laves phase and improving the strong plasticity in nickel-based superalloys manufactured by laser additive manufacturing. Taking Inconel 625 nickel-based superalloy as an example, the alloy composition is 63.59 Ni-21.5 Cr-8.5Mo-3.5 Nb-2.0 Fe- 0.2 Ti-0.2 Al-0.5 Si-0.01 C (mass percentage), the addition of carbon in the alloy is 0.2% (mass percentage);

S1: Take 2g of graphite powder with a particle size of 50nm and 998g of spherical Inconel 625 alloy powder with a particle size of 50-150µm (as shown in Figure 1) into a stainless steel ball mill jar and add absolute ethanol, and put the ball mill jar into the planetary Ball milling is carried out in a type ball mill. The ball milling process parameters are: rotating speed 160 r/min, forward rotation for 5 minutes, stop for 30 seconds, then reverse for 5 minutes, and the whole mixing process lasts for 4 hours; after the mixing is completed, take out the ball mill tank and wait for the absolute ethanol to volatilize. The ball mill jar was dried in a vacuum drying oven, the drying temperature was set at 120 °C, and the drying duration was 6 h. After drying, it was placed in a vacuum environment and cooled to room temperature;

S2: Put the powder dried in step S1 into the powder feeder, fill the forming chamber with argon as an inert protective gas, and start the forming test after the oxygen content in the forming chamber drops to 50ppm; after optimization The laser additive manufacturing process parameters are as follows: laser power 2000 W, spot diameter 5 mm, scanning speed 30 mm/s, powder feeding volume 15 g/min, powder airflow 8 L/min, lap rate 50%, the lift is 0.6 mm. Among them, the type of laser used is a fiber laser with a maximum output power of 10,000 W;

S3: The carbon-containing nickel-based superalloy powder obtained in step S1 is subjected to a block forming test according to the optimized process parameters in step S2. The laser scanning path between layers is cross-scanning, and the size of the formed sample is 80×10 ×20mm; the sample was cut along the deposition direction by wire cutting to prepare metallographic, and the surface of the sample was ground and polished with #80, #180, #400, #1000 and #2000 SiC sandpaper in sequence; in order to observe the block The macrostructure and microstructure of the bulk sample were tested, and the polished sample was chemically etched with an etchant (6 mL HCl + 2 mL H2O + 1 g CrO ₃ ). Optical microscopy (OM, LeicaMicrosystem DM-3000) and field emission scanning electron microscopy (FE-SEM, HITACHI SU8010) were used to analyze the dendrite morphology and the distribution characteristics of the second phase, as shown in Figure 3: From Figure 3 we can It can be seen that compared with the reference group without adding carbon elements, the macrostructure is still columnar dendrites, and the content of chain-like Laves phases continuously distributed between dendrites is reduced. Compared with Example 1, granular carbides are still dispersedly distributed but their content Gradually increasing, indicating that the addition of trace carbon elements plays a role in inhibiting the chain Laves phase, which has a favorable impact on the strengthening and toughening of the material. The experimental data of yield strength, tensile strength and elongation of the prepared nickel-based superalloy manufactured by laser additive manufacturing are shown in Table 1.

Example 3

A method for reducing the brittle Laves phase and improving the strong plasticity in nickel-based superalloys manufactured by laser additive manufacturing. Taking Inconel 625 nickel-based superalloy as an example, the alloy composition is 63.59 Ni-21.5 Cr-8.5Mo-3.5 Nb-2.0 Fe- 0.2 Ti-0.2 Al-0.5 Si-0.01 C (mass percentage), the addition of carbon element in the alloy is 0.4% (mass percentage);

S1: Take 4g of graphite powder with a particle size of 50nm and 996g of spherical Inconel 625 alloy powder with a particle size of 50-150µm (as shown in Figure 1) into a stainless steel ball mill jar and add absolute ethanol, and put the ball mill jar into the planetary Ball milling is carried out in a type ball mill. The ball milling process parameters are: rotating speed 160 r/min, forward rotation for 5 minutes, stop for 30 seconds, then reverse for 5 minutes, and the whole mixing process lasts for 4 hours; after the mixing is completed, take out the ball mill tank and wait for the absolute ethanol to volatilize. The ball mill jar was dried in a vacuum drying oven, the drying temperature was set at 120 °C, and the drying duration was 6 h. After drying, it was placed in a vacuum environment and cooled to room temperature;

S2: Put the dried powder in step S1 into the powder feeder, fill the laser additive manufacturing forming chamber with argon as an inert protective gas, and start the forming test after the oxygen content in the forming chamber drops to 50ppm. The optimized laser additive manufacturing process parameters are as follows: laser power 2000 W, spot diameter 5 mm, scanning speed 30 mm/s, powder feeding volume 15 g/min, powder loading airflow 8 L/min, overlap The ratio is 50%, and the lift is 0.6 mm. Among them, the type of laser used is a fiber laser with a maximum output power of 10,000 W;

S3: The carbon-containing nickel-based superalloy powder obtained in step S1 is subjected to a block forming test according to the optimized process parameters in step S2. The laser scanning path between layers is cross-scanning, and the size of the formed sample is 80×10 ×20mm. The sample was cut along the deposition direction by wire cutting to prepare metallography, and the surface of the sample was ground and polished with #80, #180, #400, #1000 and #2000 SiC sandpaper in sequence; in order to observe the bulk sample The macro and microstructure of the polished sample was chemically etched with an etchant (6 mL HCl + 2 mL H2O + 1 g CrO ₃ ); using an optical microscope (OM, Leica Microsystem DM-3000) and a field emission scanning electron microscope (FE -SEM, HITACHI SU8010) to analyze the dendrite morphology and the distribution characteristics of the second phase, as shown in Figure 4: From Figure 4, it can be seen that compared with the reference group without carbon addition, the macrostructure is still columnar dendrites The content of chain-like Laves phase continuously distributed between dendrites and dendrites decreases. Compared with Examples 1 and 2, carbides are still dispersed but their content gradually increases, and the size of carbides increases, indicating that the addition of trace carbon elements has inhibited The role of the chain Laves phase has a favorable effect on the strengthening and toughening of the material. The experimental data of yield strength, tensile strength and elongation of the prepared nickel-based superalloy manufactured by laser additive manufacturing are shown in Table 1.

Comparative example 1

The Inconel 625 nickel-based superalloy without adding carbon was used as a reference group to compare and analyze the inhibitory effect of adding carbon on the Laves phase. The alloy composition was 63.59 Ni-21.5 Cr-8.5 Mo-3.5 Nb-2.0 Fe-0.2 Ti-0.2Al- 0.5 Si-0.01 C (mass percentage);

S1: The spherical Inconel 625 alloy powder with a particle size of 50-150 µm (as shown in Figure 1) was dried in a vacuum drying oven, the drying temperature was set at 120 °C, and the drying duration was 6 h. After drying, Cool to room temperature under vacuum;

S2: Put the dried powder in step S1 into the powder feeder, fill the laser additive manufacturing forming chamber with argon as an inert protective gas, and start the forming test after the oxygen content in the forming chamber drops to 50ppm. The optimized laser additive manufacturing process parameters are as follows: laser power 2000 W, spot diameter 5 mm, scanning speed 30 mm/s, powder feeding volume 15 g/min, powder loading airflow 8 L/min, overlap The ratio is 50%, and the lift is 0.6 mm. Among them, the type of laser used is a fiber laser with a maximum output power of 10,000 W;

S3: The nickel-based superalloy powder obtained in step S1 is subjected to a block forming test according to the process parameters optimized in step S2. The laser scanning path between layers is cross-scanning, and the size of the formed sample is 80×10× 20mm; the sample is cut along the deposition direction by wire cutting to prepare the metallography, and the surface of the sample is ground and polished with #80, #180, #400, #1000 and #2000 SiC sandpaper in sequence; in order to observe the block Macro and microstructure of the specimen, the polished specimen was chemically etched with etchant (6 mL HCl + 2 mL H2O + 1 g CrO ₃ ); using an optical microscope (OM, Leica Microsystem DM-3000) and a field emission scanning electron microscope (FE-SEM, HITACHI SU8010) to analyze the dendrite morphology and the distribution characteristics of the second phase, as shown in Figure 6: From Figure 6, it can be seen that the macrostructure of the Inconel 625 alloy without adding carbon elements is columnar dendrites, There is a chain Laves phase distributed continuously between the dendrites, and the Laves phase distributed in a chain will seriously reduce the plasticity of the material. The experimental data of yield strength, tensile strength and elongation of the prepared nickel-based superalloy manufactured by laser additive manufacturing are shown in Table 1.

Comparative example 2

When a large amount of carbon is added to the alloy, a large number of continuously distributed carbides will be formed, which will have an adverse effect on the plasticity of the material. In addition, the content of carbon element in traditional superalloys is usually below 0.5% (mass percentage), so it is necessary to strictly control the amount of carbon element added in the alloy. Taking Inconel 625 nickel-based superalloy as an example, the alloy composition is 63.59 Ni-21.5 Cr-8.5Mo-3.5 Nb-2.0 Fe-0.2 Ti-0.2 Al-0.5 Si-0.01 C (mass percentage), the addition of carbon in the alloy The amount is 0.6% (mass percentage), as a comparison case of the effect of adding excess carbon on the structure of nickel-based superalloy manufactured by laser additive manufacturing.

S1: Take 6g of graphite powder with a particle size of 50nm and 994g of spherical Inconel 625 alloy powder with a particle size of 50-150µm (as shown in Figure 1) into a stainless steel ball mill jar and add absolute ethanol, and put the ball mill jar into the planetary Ball milling is carried out in a type ball mill. The ball milling process parameters are: rotating speed 160 r/min, forward rotation for 5 minutes, stop for 30 seconds, then reverse for 5 minutes, and the whole mixing process lasts for 4 hours; after the mixing is completed, take out the ball mill tank and wait for the absolute ethanol to volatilize. The ball mill jar was dried in a vacuum drying oven, the drying temperature was set at 120 °C, and the drying duration was 6 h. After drying, it was placed in a vacuum environment and cooled to room temperature;

S2: Put the dried powder in step S1 into the powder feeder, fill the laser additive manufacturing forming chamber with argon as an inert protective gas, and start the forming test after the oxygen content in the forming chamber drops to 50ppm. The optimized laser additive manufacturing process parameters are as follows: laser power 2000 W, spot diameter 5 mm, scanning speed 30 mm/s, powder feeding volume 15 g/min, powder loading airflow 8 L/min, overlap The ratio is 50%, and the lift is 0.6 mm. Among them, the type of laser used is a fiber laser with a maximum output power of 10,000 W;

S3: The carbon-containing nickel-based superalloy powder obtained in step S1 is subjected to a block forming test according to the optimized process parameters in step S2. The laser scanning path between layers is cross-scanning, and the size of the formed sample is 80×10 ×20mm; The sample was cut along the deposition direction by wire cutting to prepare the metallography, and the surface of the sample was ground and polished with #80, #180, #400, #1000 and #2000 SiC sandpaper in sequence; in order to observe the block Macroscopic and microstructure of bulk samples, polished samples were chemically etched with etchant (6 mL HCl + 2 mL H2O + 1 g CrO ₃ ); using optical microscope (OM, LeicaMicrosystem DM-3000) and field emission scanning electron microscope (FE-SEM, HITACHI SU8010) to analyze the dendrite morphology and the distribution characteristics of the second phase, as shown in Figure 5: From Figure 5, it can be seen that compared with the reference group without adding carbon, the macrostructure is still It is a columnar dendrite, and the content of the chain-like Laves phase continuously distributed between the dendrites decreases. Compared with Examples 1, 2, and 3, the content of carbides gradually increases, the size gradually increases, and the morphology gradually changes from granular to thin film , indicating that the addition of trace carbon elements can inhibit the chain-like Laves phase, but when the carbon content is high, film-like carbides will be formed, which will have an adverse effect on the plasticity of the material, so the carbon content in the alloy must be strictly controlled. The experimental data of yield strength, tensile strength and elongation of the prepared nickel-based superalloy manufactured by laser additive manufacturing are shown in Table 1.

Table 1

Yield strength (YS)/MPa Tensile strength (UTS)/MPa Elongation (δ)/% Example 1 321.2 713.1 77.80 Example 2 332.3 720.3 59.63 Example 3 343.7 725.7 53.95 Comparative example 1 316.7 696.6 49.65 Comparative example 2 338.9 730.6 26.26

The above-mentioned embodiments of the present invention are only examples for illustrating the present invention, rather than limiting the specific implementation of the present invention. For those of ordinary skill in the art, on the basis of the above examples, other changes or changes in different forms can also be made. It is not possible to give detailed examples for all implementation manners here. All obvious changes or changes derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims (8)

1. A method for reducing brittle Laves phase and improving strong plasticity in laser additive manufacturing nickel-base superalloy, is characterized in that, comprises the following steps: S1. After wet mixing nano-carbon powder and nickel-based superalloy powder in absolute ethanol according to the mass ratio, dry and cool to obtain carbon-containing nickel-based superalloy powder; S2. Put the carbon-containing nickel-based superalloy powder into the powder feeder, fill the laser additive manufacturing forming chamber with argon as an inert protective gas, and start the laser additive manufacturing forming test after the oxygen content in the forming chamber drops to 50ppm And get the process parameters of laser additive manufacturing; S3. The carbon-containing nickel-based superalloy powder obtained in step S1 is subjected to a laser additive forming test according to the process parameters of laser additive manufacturing forming in step S2 to obtain a defect-free and high-density deposited sample. Microstructure analysis and mechanical property test were carried out to clarify the influence of the introduction of carbon on the volume fraction and distribution characteristics of the brittle Laves phase and the improvement of the alloy's strong plasticity; In step S1, the mass compounding ratio of the nano-carbon powder and the nickel-based superalloy powder is (1-2): (998-999); In step S1, the nano-carbon powder is selected from graphite powder with a particle size of 40-60 nm. 2. the method for reducing the brittle Laves phase and improving the strong plasticity in the laser additive manufacturing nickel-base superalloy according to claim 1, it is characterized in that, the nickel-base superalloy powder is selected from the solid-solution-strengthened nickel-base superalloy Or a precipitation-strengthened nickel-based superalloy; the particle size of the nickel-based superalloy powder used in the coaxial powder feeding directed energy deposition process is 50-150 µm, and the particle size used in the selective laser melting process is 15-53 µm. 3. The method for reducing the brittle Laves phase and improving the strong plasticity in nickel-based superalloys manufactured by laser additive manufacturing according to claim 1, wherein, in step S1, the wet mixing is carried out in absolute ethanol by using a planetary ball mill Wet mixing is carried out in the middle, the rotation speed of the planetary ball mill is 120-200 r/min when mixing powder, forward rotation for 3-5 min, stop for 30 s, reverse rotation for 3-5 min, wet mixing time 3-6 h; Drying is drying in a vacuum drying oven, the drying temperature is 110-130 ° C, and the drying time is 4-6 h. 4. The method for reducing the brittle Laves phase and improving the strong plasticity in nickel-based superalloys manufactured by laser additive manufacturing according to claim 1, characterized in that, in step S2, the laser additive manufacturing forming is selected from coaxial powder feeding Directed energy deposition process or selected area laser melting process; the laser type used in the coaxial powder feeding directed energy deposition process is CO ₂ laser, fiber laser or semiconductor laser, and the optimized process parameters are: laser power is 1000-3000 W, the spot diameter is 2-5 mm, the scanning speed is 10-30 mm/s, the powder feeding volume is 8-20 g/min, the powder-carrying gas flow rate is 4-10 L/min, and the overlap rate is 40%- 60%, and the lifting amount is 0.4-0.6mm; the energy distribution of the laser used is Gaussian distribution or bimodal distribution, and the protective gas and carrier powder are both argon gas during the forming process; the laser used in the selective laser melting process is a fiber laser, and the obtained The optimized process parameters are: laser power 180-300 W, spot diameter 50-100 µm, scanning speed 300-1200 mm/s, scanning distance 60-100 µm, powder coating thickness 30-50 µm, used The laser can be a continuous laser or a pulsed laser with a wavelength of 1060 nm. 5. The method for reducing the brittle Laves phase and improving the strong plasticity in nickel-based superalloys manufactured by laser additive manufacturing according to claim 4, characterized in that, in step S2, the coaxial powder feeding type directed energy deposition process used The laser type is CO ₂ laser, fiber laser or semiconductor laser, and the optimized process parameters are: laser power 1000-3000W, spot diameter 2-5 mm, scanning speed 10-30 mm/s, powder feeding volume 8 -20 g/min, the powder-carrying air flow rate is 4-10L/min, the overlap rate is 40%-60%, and the lift is 0.4-0.6mm; the energy distribution of the laser used is Gaussian distribution or bimodal distribution, the forming process Both the protective gas and the carrier powder are argon. 6. The method for reducing the brittle Laves phase and improving the strong plasticity in nickel-based superalloys manufactured by laser additive manufacturing according to claim 4, wherein in step S2, the laser used in the selective laser melting process is a fiber laser, and obtains The optimized process parameters are: laser power 180-300 W, spot diameter 50-100 µm, scanning speed 300-1200 mm/s, scanning distance 60-100 µm, powder coating thickness 30-50 µm, the laser used It can be a continuous laser or a pulsed laser with a wavelength of 1060 nm. 7. The method for reducing the brittle Laves phase and improving the strong plasticity in the nickel-based superalloy produced by laser additive manufacturing according to claim 1 or 5, characterized in that, in step S3, the laser additive manufacturing forming adopts coaxial feeding In the powder directed energy deposition process, the laser scanning mode in the layer is unidirectional scanning or reciprocating scanning, and the laser scanning path between layers can be cross scanning or reciprocating scanning. 8. The method for reducing the brittle Laves phase and improving the strong plasticity in nickel-based superalloys manufactured by laser additive manufacturing according to claim 1 or 6, characterized in that, in step S3, the laser additive manufacturing is formed by selective laser melting During the process, the scanning method in the layer is unidirectional scanning or reciprocating scanning, and the interlayer rotation angle is any one of 0°, 90° or 67°.

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