CN115846689A - Solution treatment method for melting GH3230 alloy by laser powder bed and GH3230 alloy - Google Patents

Abstract

The invention relates to a solid solution treatment method for a laser powder bed melting GH3230 alloy and the GH3230 alloy, belonging to the field of high temperature alloyThe technical field of gold. In order to solve the problem that the prior art lacks a solid solution treatment method for melting GH3230 alloy by a laser powder bed, the invention provides a solid solution treatment method for melting GH3230 alloy by a laser powder bed, which comprises the following steps: preparing GH3230 alloy through a laser powder bed melting additive manufacturing system; and then heating the GH3230 alloy to 1130-1280 ℃ for solution treatment, preserving the heat for 1-3 h, and cooling to room temperature. The invention improves M while adapting to the laser powder bed fusion forming technology ₆ Volume fraction and morphological distribution of C carbide in the alloy such that M ₆ The average size of C is reduced, the stress concentration in the stretching process is reduced, the elongation of the alloy is greatly improved on the premise of ensuring higher strength of the alloy, and the GH3230 alloy with both strength and plasticity is obtained.

Description

A solid solution treatment method of laser powder bed fusion GH3230 alloy and GH3230 alloy

technical field

The invention belongs to the technical field of superalloys, and in particular relates to a solid solution treatment method for laser powder bed melting GH3230 alloy and the GH3230 alloy.

Background technique

The development of high-performance aerospace vehicles requires an increase in the thrust-to-weight ratio of the engine, which puts forward higher requirements for the hot-end parts of the engine, including the use of materials with higher high-temperature strength for service, and integrated structural design for weight reduction. GH3230 alloy is a solid solution strengthened Ni-Cr-W-Mo high-temperature alloy. The alloy has good durability and creep resistance for long-term use below 900°C. The short-term working temperature can reach 1100°C, and the long-term exposure to 1150°C The environment still has excellent oxidation resistance and thermal stability, and is widely used in aero-engine hot-end parts.

The use of traditional materials to manufacture engine hot-end components has problems such as difficult processing of new topological structures, long processing cycles, and material waste, which seriously hinder the rapid iteration of aero-engine technology. Laser powder bed fusion processing is a non-equilibrium solidification process. During the forming process, the molten pool undergoes ultra-fast solidification on the order of 10 ⁷ K/s, resulting in the inhomogeneous substructure and dislocation network of epitaxial growth in laser powder bed fusion GH3230 alloy. , and Cr, B, C, Si and other low-melting elements enriched in grain boundaries and sub-grain boundaries lead to low plasticity and performance instability caused by microstructure transformation during high-temperature service, making GH3230 alloy not suitable for direct service in the deposited state .

The invention patent application with the publication number CN114855030A "Ni-Cr-W-based superalloy suitable for selective laser melting forming and its preparation method" increases the content of precipitates to make the alloy strength exceed that of cold-rolled Haynes230, and obtains high-strength samples. However, the introduction of a large amount of Al, Ti, Nb, B and Ta elements makes the composition of the alloy different from that of GH3230, which makes the main strengthening mechanism of the alloy change from solid solution strengthening to precipitation strengthening, and the properties of the alloy change. Moreover, the prepared alloy has a large amount of Laves phase in the deposited state, and the instability of the Laves phase during long-term high-temperature service limits the application of the alloy in the combustion chamber.

Solid solution strengthening is an effective means to control the microstructure of alloys and improve the mechanical properties of alloys. The precipitation of a large number of granular M ₆ C carbides in the grains can effectively improve the strength and creep resistance of superalloys, but the coarse M ₆ C particles It will become a stress concentration point, reduce the critical load of crack initiation, and seriously affect the tensile plasticity of the alloy.

The invention patent application with the publication number CN114635059A "A Ni-Cr-W-based Alloy and Its Preparation Method" prepared Ni-Cr-W- W base alloy. The alloy of this method has uniformly grown grains and secondary carbides after adjustment, and the high-temperature durability performance is improved compared with the traditional GH3230 solution treatment. However, the unstable high-temperature environment of secondary carbides will lead to unstable performance of the alloy during high-temperature service, and the plasticity of the alloy has not been improved after solution treatment.

It can be seen that the existing solid solution treatment method of Ni-Cr-W alloy is proposed for the preparation of alloy by traditional casting, forging and rolling, but for the microstructure and high temperature stability of GH3230 alloy after non-equilibrium solidification by laser powder bed fusion solid solution The uniform control of the size characteristics of primary carbides and the control of the comprehensive properties of strong plasticity have not yet been resolved.

Contents of the invention

In order to solve the problem that the prior art lacks a solution treatment method for laser powder bed fusion GH3230 alloy, the present invention provides a solution treatment method for laser powder bed fusion GH3230 alloy and the GH3230 alloy.

Technical scheme of the present invention:

A solid solution treatment method for laser powder bed fusion GH3230 alloy, comprising the steps of:

Step 1, preparation of GH3230 alloy:

GH3230 alloy was prepared by laser powder bed fusion additive manufacturing system under the protection of inert atmosphere;

Step 2, solution treatment of GH3230 alloy:

In a vacuum environment with a pressure not greater than 1000 Pa, heat the GH3230 alloy prepared in step 1 to 1130-1280° C. for solution treatment, keep it warm for 1-3 hours, and then cool it to room temperature.

Further, the composition of the GH3230 spherical powder used in the preparation of the GH3230 alloy in step 1 satisfies the following mass percentages: C: 0.05-0.15%, Si: 0.25-0.75%, Mn: 0.30-1%, Cr: 20-24%, Fe: ≤3%, Mo: 1～3%, Co: ≤5%, W: 13～15%, Al: 0.2～0.5%, Ti: ≤0.1%, Cu: ≤0.5%, La: 0.005～0.05%, B: ≤0.005%, the balance being Ni.

Further, the composition of the GH3230 spherical powder used in the preparation of the GH3230 alloy in step 1 meets the following mass percentages: C: 0.07%, Si: 0.35%, Mn: 0.5%, Cr: 21.74%, Fe: 1.9%, Mo: 2.8%, Co: 2.1%, W: 14.7%, Al: 0.45%, Ti: 0.1%, Cu: 0.01%, La: 0.01%, B: 0.001%, and the balance is Ni.

Further, the particle size of the GH3230 spherical powder used in the preparation of the GH3230 alloy in Step 1 is 15-53 μm.

Further, the inert atmosphere in Step 1 is an argon atmosphere, and the oxygen content of the argon atmosphere is lower than 100ppm.

Further, the light source in the laser powder bed fusion additive manufacturing system described in step 1 is a YAG solid-state laser, the laser power is 120-300W, the spot diameter is 0.087mm, the laser scanning rate is 500-1300mm/s, and the powder coating thickness is 0.02 ～0.05mm, the scanning distance is 0.05～0.12mm, the scanning strategy is 67° cross-strip scanning, and the substrate preheating temperature is 80～160℃.

Further, the temperature rise of the GH3230 alloy in step 2 is from room temperature to 1130°C to 1280°C at a rate of 8-10°C/min.

Further, the cooling to room temperature described in step 2 is rapid cooling with high-pressure argon.

A GH3230 alloy obtained by the laser powder bed fusion GH3230 alloy solid solution treatment method of the present invention, the matrix of the processed GH3230 alloy is a full austenite structure, and the grain size is controlled within the range of 40-80 μm.

Further, the precipitated carbide is M ₆ C, the volume fraction of M ₆ C in the GH3230 alloy is less than 10%, the average size of M ₆ C at the original grain boundary position is less than 2 μm, and the average size of M ₆ C in the grain is less than 0.3 μm.

Beneficial effects of the present invention:

The laser powder bed fusion GH3230 solid solution treatment method provided by the invention can eliminate the substructure and dislocation network of the deposited sample, promote the occurrence of recrystallization, achieve the purpose of improving the structure and optimizing the performance of the alloy. While adapting to the laser powder bed fusion forming technology, the present invention can effectively control the characteristics of the primary stable carbide M ₆ C, so that the M ₂₃ C ₆ carbide can transform into a high-temperature stable M ₆ C, and M ₆ C accounts for 90% of the precipitated carbide. % or more, improve the volume fraction and morphological distribution of M ₆ C carbides in GH3230 alloy, reduce the average size of M ₆ C by adjusting the solution temperature, reduce the stress concentration in the stretching process, inhibit brittle cracking, and ensure that the laser The powder bed fusion GH3230 alloy has a high strength and greatly improves its elongation. The ultimate tensile strength of the GH3230 alloy obtained by the solution treatment method of the invention can reach more than 70% of the deposited GH3230 alloy, and its maximum elongation is more than 1.5 times higher than that of the deposited GH3230 alloy.

The laser powder bed fusion GH3230 solid solution treatment method of the present invention is simple, and the control effect is remarkable, realizes the controllability of the strength and elongation of the laser powder bed fusion GH3230 alloy, and lays the foundation for its application. The GH3230 alloy obtained by the solid solution treatment method of the present invention has both strength and plasticity is especially suitable for components used for a long time in a high temperature environment above 900°C, such as an aviation turbofan engine combustion chamber, an axial flow wheel, and the like.

Description of drawings

Figure 1 is a schematic diagram of the forming process of GH3230 alloy prepared by laser powder bed fusion additive;

Fig. 2 is the microstructure photo of different parts of the deposited state GH3230 alloy forming sample prepared by laser powder bed fusion additive in embodiment 1;

Fig. 3 is the microstructure photo and the carbide morphology photo of the GH3230 alloy obtained by different solution treatment methods of embodiment 1-embodiment 4;

Fig. 4 is the grain feature photo of GH3230 alloy obtained by different solution treatment methods of deposited state GH3230 alloy and embodiment 1-embodiment 4;

Fig. 5 is the contrast diagram of engineering stress-strain curves of deposited state GH3230 alloy and GH3230 alloy obtained by different solution treatment methods of embodiment 1-embodiment 4;

Fig. 6 is a comparison chart of the tensile strength and elongation of the as-deposited GH3230 alloy and the GH3230 alloy obtained by different solution treatment methods in Example 1-Example 4.

Detailed ways

The technical solution of the present invention will be further described below in conjunction with the examples, but it is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered by the present invention within the scope of protection. The process equipment or devices not specifically indicated in the following examples all adopt conventional equipment or devices in the art. If not specified, the raw materials used in the examples of the present invention, etc. can be commercially available; if not specified, this The technical means used in the embodiments of the invention are conventional means well known to those skilled in the art.

Example 1

This embodiment provides a solution treatment method for laser powder bed fusion GH3230 alloy, comprising the following steps:

Step 1, under the protection of an inert atmosphere, the GH3230 alloy is prepared by a laser powder bed fusion additive manufacturing system.

The composition of the GH3230 alloy spherical powder used in this example satisfies by mass percentage: Ni: 55.26%, Cr: 21.74%, W: 14.7%, Mo: 2.8%, Fe: 1.9%, Co: 2.1%, Mn: 0.5% , Si: 0.35%, Al: 0.45%, C: 0.07%, Ti: 0.1%, Cu: 0.01%, La: 0.01%, B: 0.001%.

Put the GH3230 alloy spherical powder with a size of 15-53 μm into the powder bin, put the 316L stainless steel substrate into the forming cabin, close the cabin door and pour in argon gas to keep the oxygen content below 100ppm, and heat it through platform resistance heating. The substrate is preheated to 100°C, and the laser powder bed fusion GH3230 alloy processing starts.

The laser used in this example is a YAG laser. The GH3230 powder is evenly spread on the substrate, and the GH3230 powder is melted and deposited on the 316L substrate by swinging the laser beam through the scanning galvanometer. The platform is lowered, and the powder is spread and melted again. of samples.

The process parameters of laser powder bed fusion additive manufacturing GH3230 alloy in this embodiment are as follows: laser power is 245W, spot diameter is 0.087mm, laser scanning rate is 900mm/s, powder coating thickness is 0.04mm, scanning distance is 0.11mm, scanning The strategy is 67° cross-strip scanning; the forming size is 71mm×10mm×10mm, and the schematic diagram of the forming process is shown in Figure 1.

The ultimate tensile strength of the deposited GH3230 formed sample obtained in this embodiment is 937MPa, and the elongation is 15%. The interior is columnar dendritic and fine cellular substructures, and a large number of dislocation networks are distributed at the boundaries of the substructures.

Step 2, solution treatment of GH3230 alloy:

Put the deposited GH3230 sample prepared in step 1 into a vacuum heat treatment furnace, heat the sample to 1130°C at a heating rate of 10°C/min in a vacuum environment with a pressure not greater than 1000Pa for solution treatment, and keep it for 2 hours Rapidly cool to room temperature with high-pressure argon.

In this embodiment, the ultimate tensile strength of the GH3230 alloy after solution treatment at 1130° C. is 900 MPa, and the elongation is 16.7%.

Example 2

This embodiment provides a solution treatment method for laser powder bed fusion GH3230 alloy. The difference between the solution treatment method of this embodiment and Example 1 is that the specific solution temperature and time of step 2 of this embodiment are:

Put the deposited GH3230 sample prepared in step 1 into a vacuum heat treatment furnace, heat the sample to 1180°C at a heating rate of 10°C/min in a vacuum environment with a pressure not greater than 1000Pa for solution treatment, and keep it for 2 hours Rapidly cool to room temperature with high-pressure argon.

In this example, the ultimate tensile strength of the GH3230 alloy after solution treatment at 1180° C. is 803 MPa, and the elongation is 18%.

Example 3

This embodiment provides a solution treatment method for laser powder bed fusion GH3230 alloy. The difference between the solution treatment method of this embodiment and Example 1 is that the specific solution temperature and time of step 2 of this embodiment are:

Put the deposited GH3230 sample prepared in step 1 into a vacuum heat treatment furnace, heat the sample to 1230°C at a heating rate of 10°C/min in a vacuum environment with a pressure not greater than 1000Pa for solution treatment, and keep it warm for 2 hours Rapidly cool to room temperature with high-pressure argon.

In this example, the ultimate tensile strength of the GH3230 alloy after solution treatment at 1230° C. is 750 MPa, and the elongation is 21%.

Example 4

This embodiment provides a solution treatment method for laser powder bed fusion GH3230 alloy. The difference between the solution treatment method of this embodiment and Example 1 is that the specific solution temperature and time of step 2 of this embodiment are:

Put the deposited GH3230 sample prepared in step 1 into a vacuum heat treatment furnace, heat the sample to 1280°C at a heating rate of 10°C/min in a vacuum environment with a pressure not greater than 1000Pa for solution treatment, and keep it warm for 2 hours Rapidly cool to room temperature with high-pressure argon.

In this example, the ultimate tensile strength of the GH3230 alloy after solution treatment at 1280° C. is 670 MPa, and the elongation is 42%.

Fig. 3 is the microstructure photo and the carbide morphology photo of the GH3230 alloy obtained by different solution treatment methods of embodiment 1-embodiment 4; the upper row of photos is a microstructure photo, and the lower row of photos is a carbide morphology photo; wherein a is for implementation The microstructure photograph of the GH3230 alloy gained in Example 1, the b figure is the microstructure photograph of the GH3230 alloy gained in Example 2, the c figure is the microstructure photograph of the GH3230 alloy gained in Example 3, and the d figure is the microstructure photograph of the GH3230 alloy gained in Example 4 photo.

Fig. 4 is the grain feature photo of deposited state GH3230 alloy and embodiment 1-embodiment 4 different solid solution treatment methods of GH3230 alloy; a picture is the grain feature picture of deposited state GH3230 alloy, b picture is embodiment 1 gained GH3230 The grain characteristic photograph of alloy, c figure is the grain characteristic photograph of embodiment 2 gained GH3230 alloy, d figure is the grain characteristic photograph of embodiment 3 gained GH3230 alloy, e figure is the grain characteristic photograph of embodiment 4 gained GH3230 alloy photo.

As shown in Figure 3 and Figure 4, the austenite grains of the GH3230 alloy obtained in Example 1 are columnar grains, and a large amount of M ₆ C precipitates at the grain boundaries and original sub-grain boundaries, and the M ₆ C particle size presents a bimodal distribution. The grain boundary M ₆ C particle size is 180-2850nm, the intra-granular M ₆ C particle size is 40-280nm, and the carbide volume fraction is 9.04vt%;

The austenite grains of the GH3230 alloy obtained in Example 2 are still columnar grains, M ₆ C grows, the grain boundary M ₆ C particle size is 570-3500nm, and the intragranular M ₆ C particle size is 60-360nm. The volume fraction of the substance is 7.79vt%;

_The austenite grains of the GH3230 alloy obtained in Example 3 undergo _{recrystallization} and transform into equiaxed grains, and a large amount of M ₆ C is solid-dissolved in the matrix. 30-350nm, carbide volume fraction 3.74vt%;

The austenite grains of the GH3230 alloy obtained in Example 4 were completely recrystallized, and M ₆ C was almost completely dissolved in the matrix, but there were still a small amount of nano-precipitated phases.

Fig. 5 is the comparison chart of engineering stress-strain curves of the deposited GH3230 alloy and the GH3230 alloy obtained by different solution treatment methods of Example 1-Example 4; Fig. 6 is the different solution treatment of the deposited GH3230 alloy and Example 1-Example 4 Comparison chart of tensile strength and elongation of GH3230 alloy obtained by the method.

It can be seen from Figure 5 and Figure 6 that with the increase of the solution temperature, the ultimate tensile strength gradually decreases while the elongation increases, and the conversion rate of tensile strength to elongation also increases; during the heating process In the case of solid solution of micron-sized grain boundary M ₆ C in the matrix, the stress concentration of the sample is reduced, while the micron-sized grain boundary M ₆ C of the solid solution treated sample at 1180°C grows, which makes the strength decrease by 13% and The elongation rate increased by 16%, and the conversion efficiency from strength to elongation rate was 1.23. After solution treatment at 1280°C, the micron-sized M ₆ C carbides at the grain boundary were almost completely eliminated, and the elongation rate of the laser powder bed fusion GH3230 sample was greatly improved. Improve 1.6 times, and keep higher room temperature tensile strength (decrease 28%), the conversion efficiency of strength to elongation is 5.71. Therefore, the appropriate heat treatment method can be selected according to the performance requirements of the target laser powder bed fusion GH3230 alloy, so as to achieve the controllability of strength and plasticity.

Example 5

This embodiment provides a solution treatment method for laser powder bed fusion GH3230 alloy. The difference between the solution treatment method of this embodiment and Example 1 is that the specific solution temperature and time of step 2 of this embodiment are:

Put the deposited GH3230 sample prepared in step 1 into a vacuum heat treatment furnace, and heat the sample to 1130°C at a heating rate of 10°C/min in a vacuum environment with a pressure not greater than 1000Pa for solution treatment. Rapidly cool to room temperature with high-pressure argon.

In this example, the ultimate tensile strength of the GH3230 alloy after solution treatment at 1130° C. is 910 MPa, and the elongation is 18.5%.

Example 6

This embodiment provides a solution treatment method for laser powder bed fusion GH3230 alloy. The difference between the solution treatment method of this embodiment and Example 1 is that the specific solution temperature and time of step 2 of this embodiment are:

Put the deposited GH3230 sample prepared in step 1 into a vacuum heat treatment furnace, and heat the sample to 1180°C at a heating rate of 10°C/min in a vacuum environment with a pressure not greater than 1000Pa for solution treatment. Rapidly cool to room temperature with high-pressure argon.

In this example, the ultimate tensile strength of the GH3230 alloy after solution treatment at 1180° C. is 824 MPa, and the elongation is 17.3%.

Example 7

This embodiment provides a solution treatment method for laser powder bed fusion GH3230 alloy. The difference between the solution treatment method of this embodiment and Example 1 is that the specific solution temperature and time of step 2 of this embodiment are:

Put the deposited GH3230 sample prepared in step 1 into a vacuum heat treatment furnace, and heat the sample to 1230°C at a heating rate of 10°C/min in a vacuum environment with a pressure not greater than 1000Pa for solution treatment. Rapidly cool to room temperature with high-pressure argon.

In this embodiment, the ultimate tensile strength of the GH3230 alloy after solution treatment at 1230° C. is 741 MPa, and the elongation is 23%.

Example 8

This embodiment provides a solution treatment method for laser powder bed fusion GH3230 alloy. The difference between the solution treatment method of this embodiment and Example 1 is that the specific solution temperature and time of step 2 of this embodiment are:

Put the deposited GH3230 sample prepared in step 1 into a vacuum heat treatment furnace, and heat the sample to 1280°C at a heating rate of 10°C/min in a vacuum environment with a pressure not greater than 1000Pa for solution treatment. Rapidly cool to room temperature with high-pressure argon.

In this example, the ultimate tensile strength of the GH3230 alloy after solution treatment at 1280° C. is 657 MPa, and the elongation is 39%.

Claims (10)

1. a solid solution treatment method of laser powder bed fusion GH3230 alloy, is characterized in that, comprises the steps: Step 1, preparation of GH3230 alloy: GH3230 alloy was prepared by laser powder bed fusion additive manufacturing system under the protection of inert atmosphere; Step 2, solution treatment of GH3230 alloy: In a vacuum environment with a pressure not greater than 1000 Pa, heat the GH3230 alloy prepared in step 1 to 1130-1280° C. for solution treatment, keep it warm for 1-3 hours, and then cool it to room temperature. 2. A solid solution treatment method for laser powder bed fusion GH3230 alloy according to claim 1, characterized in that the composition of the GH3230 spherical powder used in step 1 to prepare the GH3230 alloy satisfies by mass percentage: C: 0.05-0.15%, Si: 0.25-0.75%, Mn: 0.30-1%, Cr: 20-24%, Fe: ≤3%, Mo: 1-3%, Co: ≤5%, W: 13-15%, Al: 0.2 ～0.5%, Ti: ≤0.1%, Cu: ≤0.5%, La: 0.005～0.05%, B: ≤0.005%, and the balance is Ni. 3. A solution treatment method for laser powder bed fusion GH3230 alloy according to claim 1 or 2, characterized in that the composition of the GH3230 spherical powder used in step 1 to prepare the GH3230 alloy satisfies by mass percentage: C: 0.07%, Si: 0.35%, Mn: 0.5%, Cr: 21.74%, Fe: 1.9%, Mo: 2.8%, Co: 2.1%, W: 14.7%, Al: 0.45%, Ti: 0.1%, Cu: 0.01%, La: 0.01%, B: 0.001%, and the balance is Ni. 4. A solution treatment method for laser powder bed fusion GH3230 alloy according to claim 3, characterized in that the particle size of the GH3230 spherical powder used in the step 1 for preparing the GH3230 alloy is 15-53 μm. 5 . A solution treatment method for laser powder bed fusion GH3230 alloy according to claim 4 , wherein the inert atmosphere in step 1 is an argon atmosphere, and the oxygen content of the argon atmosphere is lower than 100 ppm. 6. A solid solution treatment method for laser powder bed fusion GH3230 alloy according to claim 5, characterized in that the light source in the laser powder bed fusion additive manufacturing system described in step 1 is a YAG solid-state laser, and the laser power is 120- 300W, the spot diameter is 0.087mm, the laser scanning rate is 500-1300mm/s, the powder coating thickness is 0.02-0.05mm, the scanning distance is 0.05-0.12mm, the scanning strategy is 67° cross-strip scanning, the substrate preheating temperature It is 80-160°C. 7. A solution treatment method for laser powder bed fusion GH3230 alloy according to claim 6, characterized in that, the temperature rise of the GH3230 alloy in step 2 is from room temperature to 1130° C. 1280°C. 8. A solution treatment method for laser powder bed fusion GH3230 alloy according to claim 7, characterized in that the cooling to room temperature in step 2 is rapid cooling with high-pressure argon. 9. A GH3230 alloy obtained by the solution treatment method of the laser powder bed fusion GH3230 alloy as claimed in any one of claims 1-8, characterized in that, the substrate of the processed GH3230 alloy is a full austenite structure, and the grain The particle size is controlled within the range of 40-80 μm. 10. According to the GH3230 alloy obtained by the solution treatment method of laser powder bed fusion GH3230 alloy according to claim 9, it is characterized in that the precipitated carbide is M ₆ C, and the volume fraction of M ₆ C in the GH3230 alloy is less than 10%. , the average size of M ₆ C at the original grain boundary position is less than 2 μm, and the average size of M ₆ C in the grain is less than 0.3 μm.

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