A rhenium-containing cobalt-nickel-based superalloy material and a preparation method thereof

Abstract

The application discloses a precipitation-strengthened rhenium-containing cobalt-nickel-based polycrystalline high-temperature alloy material and a preparation method thereof. The chemical composition of the precipitation-strengthened rhenium-containing cobalt-nickel-based polycrystalline high-temperature alloy material is as follows in percentage by weight: Ni 34-36%, Cr 16-18%, Mo 3-5%, Nb 2-4%, Al 1-3%, Re 0.5-3%, Fe 1-2%, Ti 0.5-1.5%, and the rest is Co. The preparation method comprises the following steps: (1) electric arc smelting metal element raw materials according to the chemical composition of the precipitation-strengthened rhenium-containing cobalt-nickel-based polycrystalline high-temperature alloy material to obtain an alloy ingot; (2) hot forging the alloy ingot; (3) performing solid solution treatment on the hot forged alloy ingot, cooling, removing the oxide skin and then cold rolling; and (4) performing aging treatment on the cold rolled alloy material, cooling to obtain the precipitation-strengthened rhenium-containing cobalt-nickel-based polycrystalline high-temperature alloy material.

Description

Technical Field

[0001] This invention relates to the field of polycrystalline superalloy technology, specifically to a precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material and its preparation method. Background Technology

[0002] Precipitation-strengthened Co-Ni-based superalloys have attracted widespread attention due to their ability to overcome the limitations of traditional Co-based alloys, which can only be strengthened through solid solution. Compared with nickel-based superalloys, Co-based superalloys have higher melting temperatures and superior heat resistance, thermal fatigue resistance, castability, and weldability, offering advantages under complex service conditions. They are widely used in hot-end components in aerospace, petrochemical, and nuclear power plants. The excellent high-temperature performance of precipitation-strengthened superalloys is closely related to their internal microstructure. Although the microstructure of precipitation-strengthened superalloys is relatively simple, generally containing only two phases (the γ′ phase of the L12 structure is uniformly distributed in the γ matrix of the FCC structure), the composition of these alloys is quite complex, containing more than a dozen elements. The proportions of these elements are carefully adjusted through mismatch engineering to modify the shape, volume fraction, and overall mechanical properties of the precipitates.

[0003] With the development and upgrading of industries, the demand for the heat resistance and mechanical properties of high-temperature alloys is increasing. Significant progress has been made in improving the mechanical properties of alloys through composition optimization. Adding refractory elements such as W, Mo, and Ta to alloys can greatly enhance their heat resistance. Rhenium (Re) has a significant impact on improving the performance of high-temperature alloys.

[0004] The new single-crystal superalloy (with a Re content of 1 wt%) developed by Zhou et al. achieved a yield strength of 1099 MPa at 760 °C (Zhangrui Zhou, Lirong Liu, Peisen Lv, Jian Zhang, Journal of Alloys and Compounds 2023; 960: 170840). Furthermore, in their single-crystal alloy system, the tensile strength of the alloy decreased significantly as the Re mass content increased from 1% to 1.5%.

[0005] The patent specification with publication number CN107747019A discloses a Ni-Co-Cr-Al-W-Ta-Mo high-entropy superalloy and its preparation method. Although the room temperature tensile strength is improved after adding rhenium to the alloy system, the elongation at break (plasticity) decreases significantly.

[0006] Since the addition of retinylamine (re) reduces the microstructural stability of high-temperature alloys, it is of great significance to improve the mechanical properties of Co-Ni-based high-temperature alloys while ensuring microstructural stability. Summary of the Invention

[0007] In view of the above-mentioned technical problems and the shortcomings of the field, the present invention provides a precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material, which has good structural stability and excellent mechanical properties, and has both high tensile strength and high plasticity.

[0008] The specific technical solution is as follows:

[0009] A precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material, wherein the chemical composition of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material, by weight percentage, is: Ni 34-36% (preferably 34.5-35.5%, more preferably 35%), Cr 16-18% (preferably 17-18%, more preferably 17.5%), Mo 3-5% (preferably 3.5-4.5%, more preferably 4%), Nb 2-4% (preferably 2.5-3.5%, more preferably 3%), Al 1-3% (preferably 1.5-2.5%, more preferably 2%), Re 0.5-3.0% (preferably 1-2%, more preferably 1.5-2%, even more preferably 2%), Fe 1-2% (preferably 1.2-1.8%, more preferably 1.6%), Ti 0.5-1.5% (preferably 0.5-1%, more preferably 0.8%), the remainder being Co.

[0010] The precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material provided by this invention requires strict control of the Re content. If the Re content is too low, the performance improvement of the high-temperature alloy is limited, while if the Re content is too high, precipitates will be generated, which will seriously affect the alloy performance.

[0011] Preferably, the chemical composition of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material, by weight percentage, is: Ni 34.5-35.5%, Cr 17-18%, Mo 3.5-4.5%, Nb 2.5-3.5%, Al 1.5-2.5%, Re 1.5-2%, Fe 1.2-1.8%, Ti 0.5-1%, with the remainder being Co.

[0012] In a preferred embodiment, the chemical composition of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material, by weight percentage, is: Ni 35%, Cr 17.5%, Mo 4%, Nb 3%, Al 2%, Re 2%, Fe 1.6%, Ti 0.8%, with the remainder being Co. The precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material of this preferred embodiment exhibits a stable microstructure. X-ray diffraction (XRD) results show only an FCC structure with no new phase formation. Its tensile strength at room temperature is 1250 MPa with a plasticity of 24%, and its tensile strength at 700 °C is 819 MPa with a plasticity of 13.7%, demonstrating both high tensile strength and high plasticity.

[0013] The present invention also provides a preferred preparation method for the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material, comprising the following steps:

[0014] (1) According to the chemical composition of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material, the elemental metal raw material is melted by electric arc to obtain an alloy ingot;

[0015] (2) Hot forging of the alloy ingot;

[0016] (3) The hot-forged alloy ingot is subjected to solution treatment, cooled, and cold-rolled after removing the oxide scale.

[0017] (4) The cold-rolled alloy material is subjected to aging treatment and cooled to obtain the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material.

[0018] The precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material prepared by the above method has superior tensile strength and plasticity.

[0019] In a preferred embodiment, in the method for preparing the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material, in step (1), the arc melting is carried out in an inert atmosphere. The inert atmosphere described in this invention refers to an atmosphere that will not react with the metallic elemental raw material, such as a rare gas atmosphere like argon. Further, in step (1), the gas pressure for the arc melting can be 0.01 ± 0.005 MPa.

[0020] In one embodiment, the preparation method of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material, in step (1), the specific operation of the arc melting includes: first adding three high-melting-point metallic elements, Re, Mo, and Nb, heating until the high-melting-point metallic elements begin to melt, then adding the remaining metallic elements, maintaining the temperature at 1480-1520℃ (preferably 1500℃), and after all the metallic elements have melted, holding the temperature for a period of time (preferably for more than 30 minutes), and then taking it out to obtain an alloy ingot. The above specific operation can avoid the phenomenon of over-melting and loss of the remaining low-melting-point metallic elements before the high-melting-point metallic elements have melted during the melting process.

[0021] Hot forging can improve the internal structure of the alloy. In the preparation method of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material, the hot forging temperature in step (2) can be 1180-1220℃, preferably 1200℃.

[0022] In the preparation method of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material, in step (3), the temperature of the solid solution treatment can be 1180-1220℃, preferably 1200℃, and the time can be 2-3 hours, preferably 2 hours.

[0023] In the preparation method of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material, the cooling in step (3) can be oil cooling.

[0024] In the preparation method of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material, in step (3), the deformation amount of the cold rolling can be 18-22%, preferably 20%.

[0025] In the preparation method of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material, in step (4), the aging treatment temperature can be 780-820℃, preferably 800℃, and the time can be 3-4 hours, preferably 3 hours.

[0026] In the preparation method of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material, the cooling in step (4) can be air cooling.

[0027] By further defining and optimizing through one or more of the above steps, the tensile strength and plasticity of the obtained precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material can be further improved.

[0028] Compared with the prior art, the beneficial effects of this invention are as follows:

[0029] 1. After composition optimization, the obtained precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material has significantly enhanced tensile strength and plasticity, and has excellent comprehensive mechanical properties.

[0030] 2. The method for preparing precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy materials of the present invention can effectively strengthen the alloy and enable it to obtain the best microstructure and performance state. Attached Figure Description

[0031] Figure 1 The images show the microstructure of the alloys after aging heat treatment in each of the embodiments and comparative examples, where: (a) Example 1; (b) Comparative Example 1; (c) Comparative Example 2; (d) Comparative Example 3; GB in the figures represents grain boundaries.

[0032] Figure 2 The images show the XRD patterns of the alloys after aging heat treatment in each embodiment and comparative example.

[0033] Figure 3 The graph shows a comparison of the mechanical properties of the alloys after aging heat treatment in each embodiment and comparative example at room temperature.

[0034] Figure 4 The graph shows the mechanical properties of the alloy after aging heat treatment in Example 1 at 700°C. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0036] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer.

[0037] The preparation process of the alloy materials in the following embodiments and comparative examples is described below:

[0038] The raw materials are prepared according to the element weight ratio. Each element is a high-purity metal raw material with a purity of 99.99%. According to the element ratio, the total weight of the raw materials is 100±0.05g.

[0039] All raw materials used in this application can be obtained from commercial channels.

[0040] The melting process was carried out using an electric arc furnace. The furnace was first repeatedly purged with argon gas twice to reduce the oxygen content and prevent oxidation during melting. Then, argon gas was introduced again to a slightly positive pressure of 0.01 ± 0.005 MPa. The raw materials were cleaned with anhydrous ethanol to remove oil and dust before being added to the electric arc furnace. The order of addition was as follows: first, the higher-melting-point metals Re, Mo, and Nb were added. After the high-melting-point metals began to melt, the remaining lower-melting-point metals were added. The temperature was raised to 1500℃, and after all the materials had melted, the furnace was held at that temperature for 30 minutes before removing the ingot. To ensure quality, the ingot was turned over five times during the melting process, resulting in an alloy ingot.

[0041] The obtained alloy ingots need to undergo hot forging to improve their internal structure. The alloy ingots are forged into strips with a cross-section of 12mm × 12mm at a hot forging temperature of 1200℃.

[0042] The obtained hot-forged samples were subjected to solution treatment at a temperature of 1200℃ for 2 hours, and cooled by oil cooling.

[0043] The oxide scale on the surface of the obtained solution-treated sample was completely removed, with the removal standard being the absence of obvious black spots on the material surface. The material was then cold-rolled with a deformation of 20%.

[0044] The obtained cold-rolled material is subjected to aging treatment to obtain the final material. The aging temperature is 800℃, the aging time is 3 hours, and the cooling method is air cooling.

[0045] After obtaining the final material, metallographic preparation was performed on the material by etching with 3g CuSO4 + 20mL C2H5OH + 20mL HCl etching solution (HCl concentration 37wt%) for 10-30s. The metallographic structure was then observed under a scanning electron microscope and mechanical tensile tests were performed.

[0046] Example 1

[0047] The alloy composition (wt.%) of this embodiment is as follows: Ni 35%, Cr 17.5%, Mo 4%, Nb 3%, Al 2%, Re 2%, Fe 1.6%, Ti 0.8%, and the remainder is Co.

[0048] The final microstructure of the material after aging heat treatment at 800℃ for 3 hours is as follows: Figure 1 As shown in Figure (a), the alloy has a uniform microstructure with straight and clear grain boundaries. The XRD results of the alloy are as follows: Figure 2 As shown, it is a single FCC phase with no obvious new phase characteristics. Mechanical test results are as follows... Figure 3 As shown, the alloy has a tensile strength of 1250 MPa and a plasticity of 24% at room temperature. Further testing at 700°C yielded tensile strength and plasticity of 800 MPa and 13.7%, respectively. (See attached diagram). Figure 4 .

[0049] Comparative Example 1

[0050] The alloy composition (wt.%) of this comparative example is as follows: Ni 35%, Cr 17.5%, Mo 4%, Nb 3%, Al 2%, Fe 1.6%, Ti 0.8%, and the remainder is Co.

[0051] The final microstructure of the material after aging heat treatment at 800℃ for 3 hours is as follows: Figure 1 As shown in Figure (b), the alloy has a uniform microstructure with straight and clear grain boundaries. The XRD results of the alloy are as follows: Figure 2 As shown, it is a single FCC phase with no obvious new phase characteristics. Mechanical test results are as follows... Figure 3 As shown, the alloy has a tensile strength of 1140 MPa and a plasticity of 7% at room temperature. The comparative proportion without Re has very poor plasticity.

[0052] Comparative Example 2

[0053] The alloy composition (wt.%) of this comparative example is as follows: Ni 35%, Cr 17.5%, Mo 4%, Nb 3%, Al 2%, Re 1%, Fe 1.6%, Ti 0.8%, and the remainder is Co.

[0054] The final microstructure of the material after aging heat treatment at 800℃ for 3 hours is as follows: Figure 1 As shown in Figure (c), the alloy has a uniform microstructure with straight and clear grain boundaries. The XRD results of the alloy are as follows: Figure 2 As shown, it is a single FCC phase with no obvious new phase characteristics. Mechanical test results are as follows... Figure 3 As shown, the alloy has a tensile strength of 1210 MPa and a plasticity of 13% at room temperature.

[0055] The comparison results of Comparative Examples 1 and 2 with Example 1 show that in the Co-Ni-Cr-Mo-Nb-Al-Fe-Ti precipitation-strengthened polycrystalline alloy system of the present invention, the appropriate introduction of Re to replace part of Co can significantly improve the tensile strength and plasticity of the alloy.

[0056] Comparative Example 3

[0057] The alloy composition (wt.%) of this comparative example is as follows: Ni 35%, Cr 17.5%, Mo 4%, Nb 3%, Al 2%, Re 3%, Fe 1.6%, Ti 0.8%, and the remainder is Co.

[0058] The final microstructure of the material after aging heat treatment at 800℃ for 3 hours is as follows: Figure 1 As shown in Figure (d), the alloy microstructure is homogeneous, but discontinuous precipitates are present at the grain boundaries. This composition reduces microstructural stability, and the precipitates weaken the alloy's properties. The alloy's XRD test results are as follows... Figure 2 As shown, it is a single FCC phase with a low content of precipitated phase, and XRD shows no obvious new phase characteristics. Mechanical test results are as follows... Figure 3 As shown, the alloy has a tensile strength of 1090 MPa and a plasticity of 20% at room temperature.

[0059] Compared with Example 1, Comparative Example 3 shows that adding excessive Re element will lead to a decrease in both alloy strength and plasticity.

[0060] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material, characterized in that, The chemical composition of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material, by weight percentage, is: Ni 34-36%, Cr 16-18%, Mo 3-5%, Nb 2-4%, Al 1-3%, Re 0.5-2%, Fe 1-2%, Ti 0.5-1.5%, with the remainder being Co.

2. The precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material according to claim 1, characterized in that, The chemical composition of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material, by weight percentage, is: Ni 34.5-35.5%, Cr 17-18%, Mo 3.5-4.5%, Nb 2.5-3.5%, Al 1.5-2.5%, Re 1.5-2%, Fe 1.2-1.8%, Ti 0.5-1%, with the remainder being Co.

3. The precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material according to claim 2, characterized in that, The chemical composition of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material, by weight percentage, is: Ni 35%, Cr 17.5%, Mo 4%, Nb 3%, Al 2%, Re 2%, Fe 1.6%, Ti 0.8%, with the remainder being Co.

4. The method for preparing precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline superalloy material according to any one of claims 1-3, characterized in that, Including the following steps: (1) According to the chemical composition of the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material, the metal element raw material is melted by electric arc to obtain an alloy ingot; (2) Hot forging of the alloy ingot; (3) The hot-forged alloy ingot is subjected to solution treatment, cooled, and cold-rolled after removing the oxide scale; (4) The cold-rolled alloy material is subjected to aging treatment and cooled to obtain the precipitation-strengthened rhenium-cobalt-nickel-based polycrystalline high-temperature alloy material.

5. The preparation method according to claim 4, characterized in that, In step (1): The electric arc melting is carried out in an inert atmosphere at a pressure of 0.01 ± 0.005 MPa. The specific operation of the electric arc melting includes: first adding three high-melting-point metal elements, Re, Mo and Nb, heating until the high-melting-point metal elements begin to melt, then adding the remaining metal elements, maintaining the temperature at 1480-1520℃, and holding the temperature for a period of time after all the metal elements have melted, and then taking it out to obtain an alloy ingot.

6. The preparation method according to claim 5, characterized in that, In the specific operation of the electric arc melting: the temperature is maintained at 1500℃, and after all the elemental metal raw materials have melted, the temperature is maintained for more than 30 minutes.

7. The preparation method according to claim 4, characterized in that, In step (2), the hot forging temperature is 1180-1220℃.

8. The preparation method according to claim 7, characterized in that, In step (2), the hot forging temperature is 1200℃.

9. The preparation method according to claim 4, characterized in that, In step (3): The solution treatment is performed at a temperature of 1180-1220℃ for 2-3 hours. The cooling method is oil cooling; The deformation amount of the cold rolling is 18-22%.

10. The preparation method according to claim 9, characterized in that, In step (3): The solution treatment was performed at a temperature of 1200°C for 2 hours. The deformation amount of the cold rolling is 20%.

11. The preparation method according to claim 4, characterized in that, In step (4): The aging treatment is performed at a temperature of 780-820℃ for 3-4 hours. The cooling method is air cooling.

12. The preparation method according to claim 11, characterized in that, In step (4): The aging treatment was performed at a temperature of 800°C for 3 hours.

Images