Iron-chromium-nickel-aluminum superalloy material and application method therefor

Abstract

Disclosed in the present invention are an iron-chromium-nickel-aluminum superalloy material and an application method therefor. The iron-chromium-nickel-aluminum superalloy material comprises chromium, aluminum, nickel, manganese, tungsten, molybdenum, titanium, nitrogen, tantalum, zirconium, etc. with specific mass contents, wherein the contents of chromium, aluminum and nickel satisfy the volume percentage of an NiAl precipitated phase at high temperatures being less than 3%. The iron-chromium-nickel-aluminum superalloy material of the present invention has good coking resistance, oxidation resistance and high-temperature durability, and can significantly improve the operating efficiency and economic benefits of an ethylene radiation furnace.

Description

A high-temperature alloy material of iron, chromium, nickel, and aluminum and its application method Technical Field

[0001] This invention relates to the technical field of iron-chromium-nickel-aluminum high-temperature alloy materials, and particularly to iron-chromium-nickel-aluminum high-temperature alloy materials that can be used as furnace tube materials for ethylene radiant furnaces. Background Technology

[0002] The ethylene radiant furnace is a key piece of equipment in ethylene production, converting feedstock into chemical products such as ethylene and propylene through high-temperature pyrolysis (900-1200℃). However, during the pyrolysis process, carbon and coke deposits on the inner wall of the furnace tubes, leading to coking. This causes problems such as reduced heat transfer efficiency, increased furnace tube wall temperature, and increased operating pressure, increasing energy consumption, accelerating material aging, and posing safety hazards. The decoking cycle of modern ethylene plants is typically 30-90 days, requiring production shutdowns, directly impacting operational efficiency and economic benefits. Therefore, reducing the rate of coking, extending the operating cycle, and minimizing shutdown time for decoking are crucial for improving economic efficiency.

[0003] On the other hand, the requirements for furnace tube materials in ethylene radiant furnaces are high, and they usually need to have the following characteristics: (1) high temperature strength, which can withstand the high temperature conditions of the pyrolysis reaction and have excellent creep strength; (2) anti-coking performance, such as improving the inertness of the surface, that is, reducing the contact and reaction between carbon atoms and Fe and Ni metals at high temperature; (3) corrosion resistance, in order to cope with the corrosion and carburization of the furnace tube material by the corrosive gases generated during the pyrolysis process; (4) long service life, reducing downtime and improving the reliability and stability of the equipment operation.

[0004] Currently, in high-temperature alloy furnace tubes with iron, chromium, and nickel (FeCrNi) as the main components, the chromium oxide layer on the surface becomes unstable when the temperature exceeds 900°C, leading to oxide scale vaporization or decomposition, accelerating coking and carburization, and significantly affecting the furnace tube's lifespan. Some existing technologies have made improvements, such as the iron-chromium-nickel-aluminum high-temperature alloy proposed in existing patents US 8431072 and US8815146, which allows the furnace tube to operate well at 600°C to 900°C by adding an alumina protective layer, but it cannot further meet the requirements of high-temperature environments of 900°C to 1200°C; while the high-alumina content centrifugal casting high-temperature material provided by patent EP0169119A1 improves the oxidation resistance through the alumina protective layer, its coking rate and high-temperature durability still cannot fully meet the actual needs.

[0005] In summary, the existing materials for ethylene radiant furnace tubes still have shortcomings in terms of anti-coking performance, anti-oxidation performance, and high-temperature durability under high-temperature environments. There is an urgent need to develop a new material to solve these problems and improve the operating efficiency and economic benefits of ethylene radiant furnaces. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to propose a novel iron-chromium-nickel-aluminum high-temperature alloy material with significantly improved anti-coking performance, anti-oxidation performance and high-temperature creep performance, which can significantly improve the operating efficiency and economic benefits of ethylene radiant furnaces.

[0007] The technical solution of the present invention is as follows:

[0008] A superalloy material of iron, chromium, nickel, and aluminum, comprising the following elements: carbon, manganese, silicon, chromium, nickel, aluminum, niobium, titanium, tungsten, iron, molybdenum, nitrogen, calcium, tantalum, zirconium, hafnium, yttrium, and cerium, wherein the mass percentage of carbon is 0.4-0.6 wt%, the mass percentage of nickel is 38-50 wt%, the mass percentage of chromium is 23.0-32.0 wt%, the mass percentage of manganese is less than 2 wt%, the mass percentage of silicon is 0.1-1.5 wt%, the mass percentage of aluminum is 3.0-5.0 wt%, the mass percentage of niobium is 0.5-1.5 wt%, the mass percentage of tungsten is 0.01-1 wt%, and the mass percentage of molybdenum is... The elements are: 0.01-1 wt%, titanium (0.05-0.2 wt%), nitrogen (0.005-0.2 wt%), calcium (0.001-0.5 wt%), yttrium (0.001-0.5 wt%), cerium (0.001-0.5 wt%), tantalum (0.01-0.5 wt%), zirconium (0.01-0.5 wt%), hafnium (0.001-0.5 wt%), and the mass percentages of chromium, aluminum, and nickel satisfy the condition that the value of f(x) in the following calculation model is less than 3%.

[0009]

[0010] Where f(x) represents the volume percentage of NiAl precipitates in the material, b1 represents the overall scaling parameter, b2 represents the influence coefficient of chromium, b3 represents the influence coefficient of aluminum, b4 represents the influence coefficient of nickel, b5 is a constant term, and b6 represents the exponential decay factor of temperature effect, with values ​​of: b1=1.5419, b2=-0.5839, b3=3.4687, b4=-1.3242, b5=61.3191, b6=0.2286; X cr X represents the mass percentage of chromium. Al X represents the mass percentage of aluminum. Ni The value represents the mass percentage of nickel, and T represents the absolute temperature (K) at which the iron-chromium-nickel-aluminum high-temperature alloy material is applied.

[0011] In the above solutions of the present invention:

[0012] Carbon plays an important role in high-temperature alloys. It enhances the high-temperature creep resistance of materials through carbide precipitation and also has a significant impact on the fluidity of molten steel.

[0013] Aluminum can form a dense alumina film in high-temperature alloy casting, improving the alloy's high-temperature resistance, oxidation resistance, and carburization resistance. To ensure the continuity and integrity of the alumina film, the aluminum content in the alloy should preferably be kept above 2%. However, if the aluminum content exceeds 7%, a large number of irregular, micro-sized precipitates will appear in the alloy, affecting the grain structure of the alloy and reducing the overall mechanical properties of the material. Therefore, the preferred aluminum content range should be 3-5%.

[0014] Chromium can also form oxide films or, together with aluminum oxide, form composite oxide films with excellent high-temperature oxidation resistance, effectively protecting the metal substrate from oxidation and corrosion. Furthermore, during carbide precipitation, chromium is a precursor to the carbide precipitate M. 23 C6 is the main component, enhancing the alloy's high-temperature strength and creep resistance. The inventors unexpectedly discovered that if the chromium content exceeds 35%, and nickel and aluminum are also present in the material, an unfavorable Sigma phase may form, reducing the material's mechanical properties. Therefore, the preferred chromium content is maintained between 23-32% to ensure a good balance between oxidizing properties, corrosion resistance, and mechanical properties.

[0015] Nickel is one of the key elements in casting superalloys. The presence of sufficient nickel helps stabilize austenite (face-centered cubic structure), thus endowing the alloy with high-temperature toughness and plasticity. At the same time, it promotes the precipitation of carbides, improving the alloy's durability and corrosion resistance. Furthermore, nickel is the main catalytic matrix during the coking process, and excessively high nickel content may accelerate the coking process.

[0016] The inventors unexpectedly discovered that when the nickel content exceeds 50%, in a high-temperature olefin environment, although the alloy surface is covered by an alumina film, the coking rate on the surface significantly accelerates. Therefore, controlling the nickel content below 50% can effectively slow down the coking rate in a pyrolysis environment and reduce raw material costs. Simultaneously, increasing the nickel content helps suppress the precipitation of the Sigma phase, which should not be lower than 35%. Therefore, maintaining its content between 38-50% can improve the high-temperature performance of the material.

[0017] Silicon plays several roles in high-temperature alloys, including deoxidizing molten steel, improving fluidity, and enhancing the stability of the oxide film through silicon dioxide formation, thereby increasing the alloy's oxidation resistance. However, excessive silicon content can reduce the material's deformation properties at high temperatures and affect the overall plasticity of the alloy. Therefore, it is preferable to control the silicon content within the range of 0.1-1.5 wt%.

[0018] The role of manganese in high-temperature alloys includes deoxidation and controlling sulfur (S) content, thereby improving the purity of the material. However, excessive manganese content will adversely affect the creep properties of the material and reduce the high-temperature durability of the alloy. Therefore, controlling it below 2% can ensure the optimal performance of the alloy.

[0019] Rare earth elements such as hafnium, yttrium, and cerium play roles in high-temperature alloys, including improving the stability of the oxide scale and enhancing the bonding strength between the oxide scale and the matrix material, thereby improving the long-term service performance of the material in high-temperature environments. The inventors unexpectedly discovered that controlling their content within the range of 0.001-0.5% can ensure the optimal high-temperature resistance of the material.

[0020] Tungsten can enhance the creep strength of alloys and improve the high-temperature stability of materials through solid solution strengthening at high temperatures (approximately 1100°C). However, the inventors unexpectedly discovered that excessive tungsten content may lead to the precipitation of lavas and sigmata. The growth of these precipitates affects the creep performance and ductility of the material and interferes with the diffusion of aluminum (Al) within the material, thereby reducing the long-term stability of the oxide film. Therefore, the tungsten content needs to be controlled between 0.01% and 1% to ensure optimal alloy performance.

[0021] Molybdenum can improve the high-temperature creep performance of alloys through solid solution strengthening, enhancing the stability and durability of materials in high-temperature environments. The inventors unexpectedly discovered that controlling its content within the range of 0.01-1% can ensure the optimal high-temperature performance of the alloy.

[0022] Niobium, primarily precipitated as carbides (MC), significantly enhances the durability of materials and has a crucial impact on their high-temperature creep resistance, making it a key element for improving the high-temperature resistance of alloys. The inventors unexpectedly discovered that controlling the niobium content within the range of 0.5-1.5% ensures that the alloy exhibits superior durability and high-temperature creep resistance.

[0023] The addition of titanium not only enhances the creep resistance of the alloy but also improves the material's fatigue resistance and crack resistance, thereby extending its service life. Titanium participates in the precipitation of carbides M... 23 C6 exhibits good thermal stability, effectively suppressing grain coarsening and softening. The inventors unexpectedly discovered that controlling the titanium content within the range of 0.05-0.2% ensures the material possesses optimal high-temperature mechanical properties.

[0024] Nitrogen can significantly enhance the high-temperature strength and creep resistance of alloys by precipitating nitrides, and improve the alloy's resistance to deformation and fatigue. However, excessive nitrogen content may adversely affect the material's plasticity, leading to a decrease in the alloy's high-temperature stability. The inventors unexpectedly discovered that controlling the nitrogen content within the range of 0.005-0.2% can ensure that the material maintains good creep resistance while improving its high-temperature strength.

[0025] Calcium, as a strong desulfurizing and deoxidizing agent, can effectively reduce the sulfur and oxygen content in molten steel, thereby significantly improving the purity of the alloy and enhancing the material's corrosion resistance and durability at high temperatures. The inventors unexpectedly discovered that controlling the calcium content within the range of 0.001-0.5% ensures optimal desulfurization and deoxidation effects and improves the overall performance of the material.

[0026] Tantalum, in its solid solution within high-temperature alloys, significantly increases lattice distortion, resulting in strong solid solution strengthening. This strengthening mechanism effectively improves the alloy's high-temperature strength and creep resistance, maintaining good mechanical stability under extreme service conditions. Furthermore, tantalum has a strong carbon affinity, promoting the formation of dispersion-strengthening carbides (such as TaC). These high-melting-point carbide particles, uniformly distributed in the matrix, effectively pin dislocation movement, hinder grain boundary slip and grain growth, thereby significantly improving the material's high-temperature durability and hardness.

[0027] Zirconium in high-temperature alloys can form stable ZrC carbides with carbon. These dispersed carbides effectively hinder dislocation movement, thus significantly improving the material's high-temperature hardness and creep resistance. Furthermore, zirconium promotes the stable precipitation of other strengthening phases (such as M₂₃C₆ and MC-type carbides), further enhancing the alloy's precipitation strengthening effect and improving its high-temperature strength and durability. Simultaneously, during alloy smelting, zirconium can form stable oxides or sulfides with impurity elements such as oxygen and sulfur, effectively reducing the content of non-metallic inclusions and thus improving the material's purity. This not only improves the alloy's casting properties, making its microstructure more uniform, but also enhances the stability of its mechanical properties, providing a more reliable guarantee for high-temperature service.

[0028] Building on this, the inventors unexpectedly discovered that, in the above elemental composition, especially with the combined addition of Al, Cr, and Ni, compared to the traditional precipitate M... 23In addition to the C6 and MC phases, NiAl and BCC phases also form. NiAl is a detrimental phase, forming microcracks at the boundary between the alloy matrix and the NiAl phase. These microcracks propagate further with increasing NiAl content, leading to an increased tendency for macroscopic cracking. Simultaneously, with increasing NiAl content, the BCC phase gradually appears at the NiAl grain boundaries, further exacerbating the cracking tendency. Therefore, to improve the high-temperature creep resistance of the material, it is necessary to control the NiAl volume percentage (fraction) within a low range, which will also suppress the appearance of the BCC phase. The inventors unexpectedly discovered that within a specific elemental range, the computational model can effectively predict the volume percentage of NiAl precipitates at high temperatures (e.g., 900-1200℃) using Al, Cr, Ni content and some measured parameters, thus avoiding the cracking tendency caused by NiAl precipitates and improving the high-temperature creep resistance of the furnace tube.

[0029] The inventors also unexpectedly discovered that the calculation model is applicable to high-temperature alloys with an Al content of 3-5%, a Cr content of 23-32%, a Ni content of 38-50%, and an application temperature of 900-1200℃.

[0030] It should be noted that the BCC phase, another precipitate that impairs the high-temperature performance of the material, forms at the grain boundaries between the NiAl phase and the matrix. The BCC phase only appears when the volume fraction of the NiAl phase is high. Therefore, the technical solution of this invention controls the NiAl phase content to a low range, which can effectively suppress the formation of the BCC phase.

[0031] The inventors unexpectedly discovered that when the value of f(x) is less than 3%, the material can exhibit good high-temperature creep and excellent comprehensive mechanical properties in the high-temperature range of 900-1200℃, meeting the current design requirements of engineering equipment.

[0032] Preferably, the inventors unexpectedly discovered that when the value of f(x) is less than 1%, the material can exhibit high-temperature durability performance in the high-temperature range of 900-1200℃, and the high-temperature test fracture time under the same conditions is further improved by 3 to 6 times compared with f(x) = 3%.

[0033] According to some preferred embodiments of the present invention, the iron-chromium-nickel-aluminum high-temperature alloy material contains impurity elements with a mass percentage of less than 400 ppm and the balance of iron, wherein the impurity elements include sulfur with a mass percentage of less than 100 ppm and phosphorus with a mass percentage of less than 300 ppm.

[0034] In the preferred embodiment described above, phosphorus is an impurity element that segregates at grain boundaries, significantly reducing the alloy's plasticity and toughness and increasing its brittleness, particularly leading to brittle fracture at high or low temperatures. Furthermore, the presence of phosphorus promotes grain boundary weakening, reducing the material's creep properties and endurance strength, thus affecting the long-term service capability of the high-temperature alloy. During welding, phosphorus also increases susceptibility to hot cracking, impacting weld quality and joint reliability.

[0035] Sulfur in alloys mainly exists in the form of sulfides, which readily form low-melting-point compounds such as Ni₃S₂. These compounds precipitate along grain boundaries, causing grain boundary cracking during high-temperature service, thereby reducing creep strength and performance. Furthermore, sulfide inclusions reduce the metallurgical purity of the alloy, affecting casting and mechanical property stability.

[0036] According to some preferred embodiments of the present invention, in the iron-chromium-nickel-aluminum high-temperature alloy material, the mass percentage of carbon is 0.45-0.55 wt%, the mass percentage of manganese is less than 0.5 wt%, the mass percentage of silicon is 0.5-0.9 wt%, the mass percentage of chromium is 24-31 wt%, the mass percentage of nickel is 44-47 wt%, the mass percentage of aluminum is 3.5-4.5 wt%, the mass percentage of niobium is 0.7-0.9 wt%, the mass percentage of titanium is 0.1-0.15 wt%, the mass percentage of tungsten is 0.5-0.8 wt%, and the mass percentage of tantalum is [missing information]. The composition includes 0.1-0.2 wt% of zirconium, 0.05-0.1 wt% of yttrium, 0.05-0.1 wt% of cerium, 0.05-0.1 wt% of molybdenum, 0.05-0.5 wt% of nitrogen, 0.05-0.1 wt% of hafnium, 0.01-0.2 wt% of calcium, and iron as the balance after removing impurities. The impurities are present in a mass percentage of less than 130 ppm, including less than 30 ppm of sulfur and less than 100 ppm of phosphorus.

[0037] The inventors unexpectedly discovered that, within the above range, the coking rate of the iron-chromium-nickel-aluminum high-temperature alloy material on the furnace tube surface is lower than that of iron-chromium-nickel, while its high-temperature creep performance is more than twice that of ordinary iron-chromium-nickel high-temperature alloy materials.

[0038] The present invention further discloses a method for applying the above-mentioned iron-chromium-nickel-aluminum high-temperature alloy material to the furnace tube of an ethylene radiant furnace.

[0039] For example, in some preferred embodiments, the application includes: forming the iron-chromium-nickel-aluminum high-temperature alloy material into an ethylene radiant furnace tube and subjecting it to pre-oxidation treatment.

[0040] The inventors unexpectedly discovered that when iron-chromium-nickel-aluminum high-temperature alloy materials are pretreated with an optimized oxygen partial pressure environment, the stability of the oxide scale can be enhanced, the quality of the oxide film can be effectively improved, and the service life of the furnace tubes in high-temperature and high-oxygen environments can be extended.

[0041] Preferably, the pre-oxidation treatment is performed at a temperature of 900°C for 12-36 hours.

[0042] Preferably, the oxygen partial pressure of the pre-oxidation treatment is 10. -27 Below bar.

[0043] Regarding the above preferred embodiments, the inventors unexpectedly discovered that by creating a high-temperature, low-oxygen partial pressure environment, the oxidation sequence on the surface of the iron-chromium-nickel-aluminum superalloy material can be altered. To preferentially form a complete and dense alumina film, an environment with a temperature of 900°C and an oxygen partial pressure of 10... -27 The oxidation reaction is carried out in a bar environment to obtain a stable alumina film. After it stabilizes, a chromium oxide film is formed.

[0044] Regarding the above preferred embodiments, the inventors unexpectedly discovered that, within the Al element content range of the present invention, the oxygen partial pressure has a significant impact on the thermal stability and fatigue resistance of the oxide scale. When the oxygen partial pressure exceeds 10... -27 At bar, the thermal stability of the oxide layer is significantly poor, which easily leads to the destruction of the oxide film and accelerated oxidation of the material.

[0045] The present invention has the following beneficial effects:

[0046] This invention provides a new FeCrNiAl-based alloy that can replace traditional FeCrNi-based alloys. While maintaining superior high-temperature creep performance (comparable to or better than the high-temperature alloys of the current mainstream European standard EN 1.4889), it can significantly reduce the coking rate of furnace tubes.

[0047] This invention solves the problem of easy catalytic coking on the surface of metal oxide scale caused by high nickel content in existing alloys by adjusting the nickel content in the alloy, and controls the coking rate on the material surface to a very low level.

[0048] This invention controls the composition ratio between Cr, Ni, and Al to suppress the precipitation of NiAl and BCC phases, thus solving the problem of decreased furnace tube creep performance caused by the precipitation of NiAl phase in existing alloys, and improving and stabilizing the creep performance of the material.

[0049] This invention, through a pre-oxidation process, further solves the problem of localized coking in existing alloys in high-temperature applications, provides anti-coking performance of furnace tube oxide scale, and improves the anti-coking properties of furnace tubes. Attached Figure Description

[0050] Figure 1 is a statistical analysis chart showing the changes in Ni content and weight after the first coking process for samples 1, 2, 3, 7, 8, and 9 obtained in Example 1.

[0051] Figure 2 is a statistical analysis of the weight changes of samples 1, 2, 4, and 5 obtained in Example 1 after the 50th coking process and the partial pressure of oxygen during pre-oxidation.

[0052] Figure 3 is a comparison of the NiAl phase volume fractions of samples 1, 2, 3, 4, and 5 obtained from JMatPro software and F model calculations in Example 2.

[0053] Figure 4 is a comparison of the LMP curves of samples 1, 2, 3, and 6 obtained in Example 3 with the existing material ZG50Ni45Cr35NbM.

[0054] Figure 5 shows the backscattered electron pattern image of the sample obtained in Example 4 using a scanning electron microscope.

[0055] Figure 6 shows the elemental energy spectrum of selected region 1 in Figure 5.

[0056] Figure 7 shows the elemental energy spectrum of selected region 2 in Figure 5.

[0057] Figure 8 shows the elemental energy spectrum of selected region 3 in Figure 5. Detailed Implementation

[0058] The technical solutions of the present invention will be further described below with reference to embodiments thereof. The embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0059] Example 1

[0060] Eleven high-temperature alloy material samples, namely samples 1-11, were prepared according to the compositions shown in Table 1-2:

[0061] Table 1. Elemental composition of samples 1-5

[0062]

[0063] Table 2 Elemental composition of samples 6-11

[0064]

[0065] All samples were prepared as 3 cm × 3 cm × 3 mm block metal samples, and the surface roughness was controlled to be less than 3.2 μm by machining.

[0066] All samples underwent pre-oxidation at 900℃ for 24 hours. The pre-oxidation atmosphere and oxygen partial pressure for different samples are as follows:

[0067] The pre-oxidation atmosphere for samples 1, 3, 6, 7, 8, 9, 10, and 11 consisted of 10 vol% water vapor and 90 vol% inert argon gas, with an oxygen partial pressure of approximately 10. -27 bar;

[0068] The pre-oxidation atmosphere of sample 5 consisted of 10 vol% dry air and 90 vol% water vapor, with an oxygen partial pressure of approximately 10. -10 bar;

[0069] The pre-oxidation atmosphere of sample 4 was 100 vol% water vapor, with an oxygen partial pressure of approximately 10. -20 bar;

[0070] The pre-oxidation atmosphere of sample 2 consisted of 2 vol% water vapor and 97 vol% inert argon gas, with an oxygen partial pressure of approximately 10. -30 bar.

[0071] Thermogravimetric analysis (TGA) was performed on the pre-oxidized samples to assess their coking status by measuring the increase in sample mass. The TGA was conducted using a high-temperature tubular furnace, and the experimental procedures included:

[0072] (1) Heating stage, including:

[0073] Coking process: At 1150℃, a 30 vol% water vapor and a 70 vol% C2H6 atmosphere are introduced for 2 hours;

[0074] Descaling process: At 950℃, a mixture of 50% vol water vapor and 50% vol air atmosphere is introduced for 50 minutes.

[0075] (2) Cooling and weighing stage: After each coking process and each coking process is completed, inert gas is introduced and the temperature is gradually reduced to room temperature. Then the sample is taken out and weighed.

[0076] Statistical analysis was performed on the Ni content of samples with different Ni contents (samples 1, 2, 3, 7, 8, 9, 10, 11) and their weight changes after pre-oxidation and the first coking process. The results are shown in Figure 1. Comparing samples 1, 2, 3, 7, 8, and 9, it can be seen that although a dense alumina film was formed on the surface of the material after pre-oxidation, the growth of MC and M23C6 precipitates near the surface may have led to the material matrix being exposed to a high-carbon-density, high-temperature environment, resulting in varying degrees of coking weight gain. Among them, sample 2 was pre-oxidized under a lower oxygen partial pressure than sample 1, and its surface alumina film density should be higher than that of sample 1. However, the carbon deposition rate of sample 2 is still higher than that of sample 1, indicating that the nickel content is the main factor affecting the carbon deposition rate. The results also show that when the Ni content exceeds 50%, the coking rate of the material increases threefold. Therefore, controlling the Ni content below 50% can significantly reduce the coking rate. Comparing samples 1, 10, and 11, it can be seen that the weight change of aluminum-added sample 1 after the first coking process is significantly different from that of the traditional FeCrNi products 10 and 11. Here, the Ni content is not the main reason. The main reason is that the alumina film on the surface of aluminum-added sample 1 has better stability at 1150℃ than the traditional chromium oxide film. The latter undergoes a gasification or decomposition reaction at high temperatures, causing the Fe and Ni in the parent material to be exposed to an atmosphere with high concentrations of C atoms, thereby accelerating the surface carbon deposition rate.

[0077] Furthermore, samples 1, 2, 4, and 5, all with Ni content less than 50% and undergoing different pre-oxidation processes, were subjected to the same 50 coking and 49 decoking processes. The weight changes of the samples after the 50th coking process were statistically analyzed in relation to the oxygen partial pressure during pre-oxidation. The results are shown in Figure 2. The Al and Cr contents of these samples are similar, suggesting that their oxide scale composition is approximately the same; the only difference is the oxygen partial pressure during pre-oxidation. According to Figure 2, the oxygen partial pressure of samples 1 and 2 during pre-oxidation is less than 10. -27 Bar, the coking rate was the same after 50 coking processes, and only slightly improved compared to the first coking process. The pre-oxidation oxygen partial pressure of samples 4 and 5 was 10. -20 and 10 -10 According to Bar, as the oxygen partial pressure increases, the coking rate of the material accelerates. Therefore, to ensure the high-temperature performance of the material in environments above 1000℃, the oxygen partial pressure during pre-oxidation should be around 10. -27 It is best suited for low-oxygen, high-temperature environments below bar.

[0078] Example 2

[0079] The volume fraction of NiAl precipitates in samples 1, 2, 3, 4, and 5 in Example 1 at steady state at 900℃ was calculated using JMatPro software and the F model.

[0080] JMatPro software is a professional materials simulation software widely used to calculate the thermophysical properties and phase transformation behavior of materials. In precipitate studies, JMatPro can predict the types, volume fractions, and stability of precipitates in alloy materials under different temperatures, compositions, and heat treatment conditions through thermodynamic calculations. In this embodiment, the compositions of samples 1, 2, 3, 4, and 5 were input into JMatPro software, and a nickel-based superalloy database was selected to obtain the volume percentage of NiAl precipitates in the above samples at a steady state of 900℃.

[0081] The F-model calculation is as follows:

[0082]

[0083] Where f(x) represents the volume percentage of the NiAl phase, b1 represents the overall scaling parameter, b2 represents the influence coefficient of chromium, b3 represents the influence coefficient of aluminum, b4 represents the influence coefficient of nickel, b5 is a constant term, and b6 represents the exponential decay factor of temperature effect, with values ​​of: b1=1.5419, b2=-0.5839, b3=3.4687, b4=-1.3242, b5=61.3191, b6=0.2286; X cr X represents the percentage of chromium by mass. Al X represents the percentage of aluminum by mass. Ni The value represents the percentage of nickel by mass, and T represents the absolute temperature (K) of the material when used in high-temperature applications. Here, the absolute temperature corresponding to 900℃ is 1173.15K.

[0084] The calculation results from JMatPro show that the NiAl phase volume fractions of samples 1, 2, 3, 4, and 5 at steady state of 900℃ are 1.19, 3.13, 4.24, 0.13, and 1.19, respectively. The comparison between these results and the calculation results from the F model is shown in Figure 3. It can be seen that the F model is accurate.

[0085] Example 3

[0086] Five sets of high-temperature endurance tests were conducted on samples 1, 2, 3, and 6 in Example 1. The experimental procedure was as follows: at 950°C, tensile forces of 35 MPa, 30 MPa, and 25 MPa were applied to each sample respectively; at 1150°C, the samples completed two high-temperature endurance tests under a tensile force of 12 MPa, and their fracture time under different pressures was recorded.

[0087] The volume percentages of NiAl phases 1, 2, 3, and 6 in the above samples at 950℃, calculated according to the F model, are 1.04, 3.13, 4.24, and 2.14, respectively.

[0088] The experimental results are shown in Table 3 below:

[0089] Table 3 Results of High Temperature Duration Test

[0090]

[0091] The above experimental results were compared with the LMP curves of the existing ZG50Ni45Cr35NbM (corresponding to European standard En 1.4889) heat-resistant and corrosion-resistant alloy. The results are shown in Figure 4. It can be seen that in the temperature range of 950-1150℃, when the volume percentage of NiAl phase in the sample is higher than 3.13%, the high-temperature creep performance of the sample is lower than the minimum value of the LMP curve of ZG50Ni45Cr35NbM alloy, and the high-temperature performance of the material gradually decreases as this value increases. When the percentage of NiAl precipitates in the material is less than or equal to 1%, the high-temperature performance of the material is comparable to or slightly higher than that of ZG50Ni45Cr35NbM.

[0092] The results also showed that sample 6, due to the addition of 5% W, had a significantly lower creep performance than the minimum value of ZG50Ni45Cr35NbM, despite the calculated volume percentage of the NiAl phase being 2.14%. This was mainly because not only was there 2.14% NiAl in the parent material, but the addition of W also generated the sigma and Laves phases, which reduced the high-temperature creep performance.

[0093] Example 4

[0094] Samples were taken from the fractured sample 1 after being subjected to a tensile force of 35 MPa at 950℃ for 890 hours. The sampling location was the bearing end of the sample, i.e., the part that was only subjected to high temperature but not tensile force. The microstructure was observed, and the results are shown in Figures 5-8. Figure 5 is an image in backscattered electron mode from a scanning electron microscope, and Figures 6 to 8 are the elemental energy spectra of selected regions 1, 2, and 3, respectively. Among them, Figures 6 and 7 correspond to M, M, and M, respectively. 23 The energy spectrum of C6 precipitate (M represents a certain metal element, mainly Cr element here) and MC precipitate (M mainly Nb element here) is shown in Figure 8. As can be seen from the energy spectrum of the material matrix, as predicted by the F model calculation results, no NiAl phase and BCC phase were found in the microstructure of sample 1, and the material has good high-temperature creep performance.

[0095] It should be noted that the above descriptions are merely preferred embodiments of the present invention and should not limit the scope of protection of the technical solutions of the present invention. Any modifications made to the technical solutions described in the foregoing embodiments, or equivalent substitutions of technical features, by those skilled in the art within the spirit and principles of the present invention, should be included within the scope of protection of the present invention.

Claims

1. A high-temperature alloy material of iron, chromium, nickel, and aluminum, characterized in that, It includes the following elements: The elements are carbon, manganese, silicon, chromium, nickel, aluminum, niobium, titanium, tungsten, iron, molybdenum, nitrogen, calcium, tantalum, zirconium, hafnium, yttrium, and cerium. Specifically, the mass percentages of carbon, nickel, chromium, and tungsten are: 0.4-0.6 wt%, nickel, chromium, manganese (below 2 wt%), silicon, aluminum, niobium, tungsten, and molybdenum. The mass percentages of titanium, nitrogen, calcium, yttrium, cerium, tantalum, zirconium, and hafnium are 0.001-0.5 wt%, respectively, and the mass percentages of chromium, aluminum, and nickel are such that the value of f(x) in the following calculation model is less than 3%.

2. Among them, f(x) represents the volume percentage of NiAl precipitates in the material, b1 represents the overall scaling parameter, b2 represents the influence coefficient of chromium, b3 represents the influence coefficient of aluminum, b4 represents the influence coefficient of nickel, b5 is a constant term, and b6 represents the exponential decay factor of temperature effect, with values ​​of: b1=1.5419, b2=-0.5839, b3=3.4687, b4=-1.3242, b5=61.3191, b6=0.2286; X cr X represents the mass percentage of chromium. Al X represents the mass percentage of aluminum. Ni The value represents the mass percentage of nickel, and T represents the absolute temperature at which the iron-chromium-nickel-aluminum high-temperature alloy material is applied.

3. The iron-chromium-nickel-aluminum high-temperature alloy material according to claim 1, characterized in that, The mass percentages of chromium, aluminum, and nickel elements satisfy the condition that the value of f(x) in the calculation model is less than 1%.

4. The iron-chromium-nickel-aluminum high-temperature alloy material according to claim 1, characterized in that, It contains impurity elements with a mass percentage of less than 400 ppm and the balance of iron, wherein the impurity elements include sulfur with a mass percentage of less than 100 ppm and phosphorus with a mass percentage of less than 300 ppm.

5. The iron-chromium-nickel-aluminum high-temperature alloy material according to claim 1, characterized in that, in, The carbon content is 0.45-0.55 wt%, the manganese content is below 0.5 wt%, the silicon content is 0.5-0.9 wt%, the chromium content is 24-31 wt%, the nickel content is 44-47 wt%, the aluminum content is 3.5-4.5 wt%, the niobium content is 0.7-0.9 wt%, the titanium content is 0.1-0.15 wt%, the tungsten content is 0.5-0.8 wt%, and the tantalum content is 0.1-0.2 wt%. The composition comprises 0.05-0.1 wt% zirconium, 0.05-0.1 wt% yttrium, 0.05-0.1 wt% cerium, 0.05-0.5 wt% molybdenum, 0.05-0.1 wt% nitrogen, 0.05-0.1 wt% hafnium, 0.01-0.2 wt% calcium, and iron as the balance excluding impurities. The impurities are present in a mass percentage of less than 130 ppm, including less than 30 ppm sulfur and less than 100 ppm phosphorus.

6. The iron-chromium-nickel-aluminum high-temperature alloy material according to claim 1, characterized in that, in, The elemental composition is as follows: carbon 0.42 wt%, manganese 0.1 wt%, silicon 0.41 wt%, chromium 25 wt%, nickel 45.1 wt%, aluminum 4.0 wt%, niobium 0.9 wt%, titanium 0.11 wt%, tungsten 0.8 wt%, and tantalum 0 wt%. The composition includes 0.14 wt% zirconium, 0.06 wt% yttrium, 0.01 wt% cerium, 0.3 wt% molybdenum, 0.11 wt% nitrogen, 0.012 wt% hafnium, 0.012 wt% calcium, and iron (excluding impurities, including 21 ppm sulfur and 200 ppm phosphorus).

7. The application of the iron-chromium-nickel-aluminum high-temperature alloy material according to any one of claims 1-5 in the furnace tubes of an ethylene radiant furnace.

8. The application according to claim 6, comprising: The iron-chromium-nickel-aluminum high-temperature alloy material is used to form the furnace tube of an ethylene radiant furnace and then subjected to pre-oxidation treatment.

9. The application according to claim 7, characterized in that, The pre-oxidation treatment is performed at a temperature of 900°C for 12-36 hours.

10. The application according to claim 7, characterized in that, The oxygen partial pressure of the pre-oxidation is 10. -27 Below bar.

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