Nickel-based heat-resistant alloy and preparation method thereof

Abstract

The invention belongs to the technical field of nickel-based heat-resistant alloy preparation, and discloses a nickel-based heat-resistant alloy and a preparation method thereof. The nickel-based heat-resistant alloy provided by the invention comprises the following chemical components in percentage by mass: 0.03-0.15% of C; mn < = 1.00%; less than or equal to 0.50% of Si; p is less than or equal to 0.01%; s is less than or equal to 0.01%; cr: 20.00% to 24.00%; ni: the balance; 0.50% or less of Cu; 1.50% to 2.50% of Al; fe < = 15.00%; 0.10% to 0.50% of Ti; b: 0.002% to 0.005%; 0.50% to 2.00% of W; 0.50% to 2.00% of Nb; wherein 1.5% < = W + Nb < = 3.5%; nb / C > = 15. The nickel-based heat-resistant alloy can stably serve at the temperature of 1200 DEG C or above.

Description

Technical Field

[0001] The present invention relates to the technical field of nickel-based heat-resistant alloy preparation, and specifically relates to a nickel-based heat-resistant alloy and a preparation method thereof. Background Art

[0002] Nickel-based alloys are widely used in key equipment fields such as petrochemical industry and aerospace due to their excellent oxidation resistance and corrosion resistance.

[0003] In the prior art, the maximum service temperature of nickel-based alloy such as 601 does not exceed 1200°C. For high-end equipment, such as a vertical bright annealing furnace, the furnace internal components are made of 601 nickel-based alloy, and the process temperature of the vertical bright annealing furnace needs to reach 1200 - 1250°C, resulting in the existing 601 nickel-based alloy being prone to deformation under long-term high temperature, affecting the equipment life and the stability of the production line, which restricts the actual production of products.

[0004] Therefore, it is urgent to develop a high-performance nickel-based heat-resistant alloy that can stably serve at temperatures above 1200°C. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a high-performance nickel-based heat-resistant alloy that can stably serve at temperatures above 1200°C and a preparation method thereof.

[0006] The nickel-based heat-resistant alloy according to the present invention includes the following chemical components in mass percentages: C: 0.03% - 0.15%; Mn ≤ 1.00%; Si ≤ 0.50%; P ≤ 0.01%; S ≤ 0.01%; Cr: 20.00% - 24.00%; Ni: the balance; Cu ≤ 0.50%; Al: 1.50% - 2.50%; Fe ≤ 15.00%; Ti: 0.10% - 0.50%; B: 0.002% - 0.005%; W: 0.50% - 2.00%; Nb: 0.50% - 2.00%; wherein, 1.5% ≤ W + Nb ≤ 3.5%; Nb / C ≥ 15.

[0007] Further, 2.5% ≤ W + Nb ≤ 3.5%; Nb / C ≥ 20.

[0008] Further, the content of C is 0.05 - 0.15%.

[0009] Further, the content of Al is 2% - 2.5%.

[0010] Further, the content of B is 0.003% - 0.005%.

[0011] Further, the content of Ti is 0.15% - 0.20%.

[0012] Further, the content of Cr is 22.00% - 24.00%.

[0013] The preparation method of the nickel-based heat-resistant alloy according to the present invention includes the following steps: Step 1: Melting is carried out successively using an intermediate frequency furnace, an argon oxygen decarburization furnace, and a ladle refining furnace, and controlling the components of each element within the range defined for the nickel-based heat-resistant alloy; Step 2: The molten steel after melting is cast into an alloy ingot by die casting, and the alloy ingot is formed into a plate after rolling and heat treatment; Step 3: The plate is placed in an atmospheric environment at 1200 - 1300 °C, with 30 hours of heat preservation and 1 hour of cooling as one cycle. After four cycles, the metal loss is verified.

[0014] Further, in Step 1, the vacuum degree during the refining process of the argon oxygen decarburization furnace is controlled at 10 - 30 Pa, the refining time is 30 - 60 minutes, the argon gas flow rate is 10 - 15 L / min, and the oxygen content at the end of decarburization is ≤20 ppm.

[0015] Further, in Step 2, the rolling temperature is 1150 - 1250 °C, and the total deformation amount is 60 - 80%.

[0016] Compared with the traditional nickel-based heat-resistant alloy 601, the present invention significantly improves the oxidation resistance, creep resistance, and high-temperature strength of the alloy at 1200 - 1250 °C through composition optimization (such as precise control of elements such as Al, W, Nb, Cr, etc.) and innovation in the preparation process (such as vacuum refining and optimization of rolling parameters). The metal loss can be reduced by more than 50%, solving the problem of deformation of high-temperature equipment, and having significant technical advantages and market competitiveness. Description of the Drawings

[0017] Figure 1 It is a flowchart of the preparation method of the nickel-based heat-resistant alloy according to the embodiment of the present invention. Detailed Embodiments

[0018] In order to better understand the purpose, structure, and function of the present invention, the present invention will be further described in detail below with reference to the drawings.

[0019] The nickel-based heat-resistant alloy according to the embodiment of the present invention may include the following chemical components by mass percentage: C: 0.03% - 0.15%; Mn ≤ 1.00%; Si ≤ 0.50%; P ≤ 0.01%; S ≤ 0.01%; Cr: 20.00% - 24.00%; Ni: the balance; Cu ≤ 0.50%; Al: 1.50% - 2.50%; Fe ≤ 15.00%; Ti: 0.10% - 0.50%; B: 0.002% - 0.005%; W: 0.50% - 2.00%; Nb: 0.50% - 2.00%; wherein, 1.5% ≤ W + Nb ≤ 3.5%; Nb / C ≥ 15.

[0020] In the nickel-based heat-resistant alloy of the embodiment of the present invention, by precisely controlling the alloy composition, especially the ratio of W, Nb, Nb and C, the balance between precipitation strengthening and solid-solution strengthening is optimized, significantly improving the oxidation resistance, creep resistance and mechanical properties of the alloy in the high-temperature environment of 1200-1250°C. At the same time, the processing performance and welding performance of the alloy are optimized.

[0021] In the nickel-based heat-resistant alloy of the embodiment of the present invention, C plays a dual role of solid solution and precipitation strengthening in this nickel-based alloy. If the added C content is too high (i.e., exceeding 0.15%), C will combine with Ti and Nb elements in the alloy to form too many large-sized precipitates, affecting the high-temperature performance of the alloy. If the C content is too low (i.e., lower than 0.03%), it cannot play a dual role of solid solution and precipitation strengthening. Therefore, the C content is controlled at 0.03-0.15%. Si is a harmful element in this alloy, which will promote the precipitation of harmful phases. When the Si content is greater than 0.5%, harmful Si-containing precipitates will precipitate at the grain boundaries, weakening the grain boundary strength and leading to cracking. Therefore, the Si content is controlled at ≤0.5%. Mn is a harmful element in this alloy, which will reduce the corrosion resistance. Therefore, the Mn content is controlled at ≤1.0%. Ni is the matrix alloying element, and the above content mainly plays a comprehensive role in high-temperature corrosion resistance, high creep resistance and stable precipitation phase. Cr is an indispensable alloying element, which plays a role in solid-solution strengthening and improving the comprehensive corrosion resistance. Since the very important role of Cr in the γ matrix is to form Cr 2 O 3 type oxide film, controlling the Cr content at 20%-24% can endow the alloy with good oxidation resistance and corrosion resistance. W is a solid-solution strengthening element, which improves the high-temperature strength and creep resistance of the alloy. When the W content is higher than 2%, banded distribution is easily formed in the structure, reducing the corrosion resistance. When the W content is lower than 0.5%, its effect is not obvious. Therefore, the W content is controlled at 0.5%-2.0%. Nb is a solid-solution and precipitation strengthening element, which improves the high-temperature strength and creep resistance of the alloy. When the Nb content is higher than 2%, large primary carbides are easily formed in the structure, reducing the high-temperature toughness of the material. When the Nb content is lower than 0.5%, its effect is not obvious. Therefore, the Nb content is controlled at 0.5%-2.0%. Al is the main alloying element, which improves the high-temperature oxidation resistance of the alloy. Its oxidation product (Al 2 O 3 ) can significantly improve Cr 2 O 3The density of the oxide film and its spalling resistance performance. When Al ≤ 1.5%, it can only function below 1200°C. When Al ≥ 2.5%, the hot working performance of the alloy will deteriorate. Therefore, the Al content is controlled within 1.5% - 2.5%. B belongs to micro-alloying elements, which play a role in purifying grain boundaries and improving the high-temperature creep resistance of the alloy. When B ≤ 0.002%, the effect is not obvious. When B ≥ 0.005%, it will affect the subsequent welding performance. Therefore, the B content is controlled within 0.002% - 0.005%. Ti belongs to micro-alloying elements, and its content can play a role in improving welding performance.

[0022] In a preferred embodiment, 2.5% ≤ W + Nb ≤ 3.5%; Nb / C ≥ 20. A higher total amount of W + Nb and Nb / C ratio can enhance the stability of precipitation phases (such as carbonitrides), contribute to further strengthening the high-temperature creep resistance and creep rupture strength, and are applicable to extreme high-temperature environments.

[0023] According to the present invention, in a preferred embodiment, the content of C can be 0.05 - 0.15%. By optimizing the carbon content, both the precipitation of large-sized carbides caused by excessive C (reducing toughness) is avoided, and sufficient precipitation strengthening effect is ensured, thus enhancing the high-temperature strength and deformation resistance.

[0024] In a preferred embodiment, the content of Al can be 2% - 2.5%. The optimization of the Al content can promote the formation of Al 2 O 3 oxide film, significantly improving the spalling resistance of the alloy at extreme high temperatures, thereby significantly enhancing the high-temperature oxidation resistance of the alloy, especially suitable for long-term high-temperature service environments.

[0025] In a preferred embodiment, the content of B can be 0.003 - 0.005%. The optimization of the B content further improves the high-temperature creep resistance of the alloy without affecting the welding performance.

[0026] In a preferred embodiment, the content of Ti can be 0.15% - 0.20%. The further optimization of Ti element helps to refine the precipitation phase, improve the welding performance and high-temperature toughness, and reduce the crack tendency during the processing.

[0027] In a preferred embodiment, the content of Cr can be 22.00% - 24.00%. A higher Cr content strengthens the continuity of the Cr 2 O 3 oxide film, contributing to significantly enhancing the high-temperature oxidation and corrosion resistance.

[0028] Such as Figure 1As shown, the preparation method of the above nickel-based heat-resistant alloy according to the embodiments of the present invention may include the following steps: Step 1 S1: Melting is carried out successively using an intermediate frequency furnace, an argon oxygen decarburization furnace, and a ladle refining furnace, and controlling the components of each element within the range defined for the nickel-based heat-resistant alloy; Step 2 S2: The molten steel after melting is cast into an alloy ingot by die casting, and the alloy ingot is formed into a sheet after rolling and heat treatment; Step 3 S3: The sheet is placed in an atmospheric environment at 1200 - 1300 °C, with 30 hours of heat preservation and 1 hour of cooling as a cycle. After four cycles, the metal loss is verified.

[0029] The preparation method of the above nickel-based heat-resistant alloy according to the embodiments of the present invention can ensure the uniformity of alloy composition and the stability of the microstructure by controlling the components of each element within the range defined for the nickel-based heat-resistant alloy and successively using an intermediate frequency furnace, an argon oxygen decarburization furnace, and a ladle refining furnace for melting. At the same time, the organizational structure of the alloy is optimized, significantly improving the oxidation resistance, creep resistance, and mechanical properties of the alloy, and optimizing the processing performance and welding performance of the alloy.

[0030] Preferably, in Step 1, the vacuum degree during the refining process of the argon oxygen decarburization furnace can be controlled at 10 - 30 Pa, the refining time is 30 - 60 minutes, the argon flow rate is 10 - 15 L / min, and the oxygen content at the end of decarburization is ≤ 20 ppm. By precisely controlling the decarburization process, the content of impurity elements can be reduced, and the purity of the alloy can be improved.

[0031] More preferably, the rolling temperature in Step 2 can be 1150 - 1250 °C, and the total deformation amount can be 60 - 80%. By the coordinated control of the rolling temperature and the deformation amount, dynamic recrystallization can be promoted, forming a uniform fine-grained structure, which helps to further enhance the high-temperature strength and fatigue resistance.

[0032] The following Table 1 shows the alloy compositions of the specific embodiments of the nickel-based heat-resistant alloy according to the embodiments of the present invention and the alloy composition of the comparative example (conventional nickel-based heat-resistant alloy 601):

[0033] Table 1

[0034]

[0035] For the alloy compositions of each embodiment in Table 1, the following gives specific embodiments of preparing a nickel-based heat-resistant alloy using the preparation method of the nickel-based heat-resistant alloy according to the embodiments of the present invention:

[0036] Example 1:

[0037] Smelting is carried out using an intermediate frequency furnace + argon oxygen decarburization furnace (AOD) + ladle furnace (LF) + ingot casting. The actual composition is shown in Example 1 of Table 1. The ingot is rolled and heat-treated into a plate. Among them, the vacuum degree during the refining process of the argon oxygen decarburization furnace (AOD) is controlled at 20 Pa, the refining time is 50 minutes, the argon gas flow rate is 15 L / min, and the oxygen content at the end of decarburization is 15 ppm; the rolling temperature is 1200 °C, and the total deformation is 70%. The plate is kept at 1250 °C in the atmosphere for 30 h of heat preservation and 1 h of cooling as a cycle. The metal loss during heat preservation and cooling in four cycles is 122 g / m 2 .

[0038] Example 2:

[0039] Smelting is carried out using an intermediate frequency furnace + argon oxygen decarburization furnace (AOD) + ladle furnace (LF) + ingot casting. The actual composition is shown in Example 2 of Table 1. The ingot is rolled and heat-treated into a plate. Among them, the vacuum degree during the refining process of the argon oxygen decarburization furnace (AOD) is controlled at 20 Pa, the refining time is 50 minutes, the argon gas flow rate is 15 L / min, and the oxygen content at the end of decarburization is 15 ppm; the rolling temperature is 1200 °C, and the total deformation is 70%. The plate is kept at 1250 °C in the atmosphere for 30 h of heat preservation and 1 h of cooling as a cycle. The metal loss during heat preservation and cooling in four cycles is 107 g / m 2 .

[0040] Example 3

[0041] Smelting is carried out using an intermediate frequency furnace + argon oxygen decarburization furnace (AOD) + ladle furnace (LF) + ingot casting. The actual composition is shown in Example 3 of Table 1. The ingot is rolled and heat-treated into a plate. Among them, the vacuum degree during the refining process of the argon oxygen decarburization furnace (AOD) is controlled at 20 Pa, the refining time is 50 minutes, the argon gas flow rate is 15 L / min, and the oxygen content at the end of decarburization is 15 ppm; the rolling temperature is 1200 °C, and the total deformation is 70%. The plate is kept at 1250 °C in the atmosphere for 30 h of heat preservation and 1 h of cooling as a cycle. The metal loss during heat preservation and cooling in four cycles is 119 g / m 2 .

[0042] Comparative example:

[0043] Select traditional nickel-based heat-resistant alloy 601 plate, and the actual composition is shown in the comparative example of Table 1. It is kept at 1250 °C in the atmosphere for 30 h of heat preservation and 1 h of cooling as a cycle. The metal loss during heat preservation and cooling in four cycles is 240 g / m 2 .

[0044] It can be seen that the metal loss rates of the nickel-based heat-resistant alloys in Embodiments 1 to 3 of the present invention are all significantly smaller than that of the traditional nickel-based heat-resistant alloy 601 plate, and the metal loss can be reduced by more than 50%. This verifies that the nickel-based heat-resistant alloy of the embodiment of the present invention significantly improves the performance of the alloy in the high-temperature environment of 1200-1250°C compared with the traditional nickel-based heat-resistant alloy 601. Therefore, it can effectively solve the problem of deformation of high-temperature equipment and has significant technical advantages and market competitiveness.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered by the scope of the claims and the description of the present invention. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A nickel-based heat-resistant alloy, characterized in that: The chemical composition includes the following mass percentages: C: 0.03%-0.15%; Mn≤1.00%; Si≤0.50%; P≤0.01%; S≤0.01%; Cr: 20.00%-24.00%; Ni: balance; Cu≤0.50%; Al: 1.50%-2.50%; Fe≤15.00%; Ti: 0.10%-0.50%; B: 0.002%-0.005%; W: 0.50%-2.00%; Nb: 0.50%-2.00%; among which, 1.5%≤W+Nb≤3.5%; Nb / C≥15.

2. The nickel-based heat-resistant alloy according to claim 1, characterized in that: 2.5%≤W+Nb≤3.5%; Nb / C≥20.

3. The nickel-based heat-resistant alloy according to claim 1, characterized in that: The C content is 0.05-0.15%.

4. The nickel-based heat-resistant alloy according to claim 1, characterized in that: The Al content is 2%-2.5%.

5. The nickel-based heat-resistant alloy according to claim 1, characterized in that: The content of B is 0.003%-0.005%.

6. The nickel-based heat-resistant alloy according to claim 1, characterized in that: The content of Ti is 0.15%-0.20%.

7. The nickel-based heat-resistant alloy according to claim 1, characterized in that: The Cr content is 22.00%-24.00%.

8. A method for preparing a nickel-based heat-resistant alloy according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: using a medium frequency furnace, an argon oxygen decarburization furnace and a ladle refining furnace to perform smelting in sequence, and controlling the composition of each element to be within the range specified by the nickel-based heat-resistant alloy; Step 2: Casting the molten steel into alloy ingots, and forming the alloy ingots into plates after rolling and heat treatment; Step 3: Place the plate in an atmosphere of 1200-1300°C, with 30 hours of heat preservation and 1 hour of cooling as one cycle. After four cycles, verify the amount of metal loss.

9. The method for preparing a nickel-based heat-resistant alloy according to claim 8, characterized in that: In the step 1, the vacuum degree of the argon oxygen decarburization furnace refining process is controlled at 10-30 Pa, the refining time is 30-60 minutes, the argon gas flow rate is 10-15 L / min, and the oxygen content at the decarburization endpoint is ≤20 ppm.

10. The method for preparing a nickel-based heat-resistant alloy according to claim 8, characterized in that: In the step 2, the rolling temperature is 1150-1250° C., and the total deformation is 60-80%.

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