A high-temperature-resistant and corrosion-resistant alloy material and a preparation method thereof

Abstract

The application relates to the field of alloy materials, in particular to a high-temperature-resistant and corrosion-resistant alloy material and a preparation method thereof.The alloy material comprises the following components in percentage by mass: C<=0.25%, Si<=1.50%, Mn<=2.00%, Ti is 1.5-3%, Cr is 22.0-25.0%, Ni is 18.0-21.0%, Mo is 2.5-4.5%, V is 3.5-5%, P<=0.045%, S<=0.030%, and the balance is Fe and inevitable impurities.The high-temperature-resistant and corrosion-resistant alloy material has excellent high-temperature mechanical properties, high oxidation resistance, high electrochemical corrosion resistance and high chemical corrosion resistance.The alloy material can be well applied to industrial applications in a high-temperature and high-corrosion environment, such as high-temperature fluid heaters, aerospace, energy and chemical engineering and the like.

Description

Technical Field

[0001] This invention relates to the field of alloy materials, and more particularly to a high-temperature resistant and corrosion-resistant alloy material and its preparation method. Background Technology

[0002] With the continuous development of industrial technology, the requirements for material performance are becoming increasingly stringent, especially in high-temperature and highly corrosive environments, where traditional materials often struggle to meet the demands. Therefore, developing an alloy material with excellent high-temperature mechanical properties, oxidation resistance, electrochemical corrosion resistance, and chemical corrosion resistance has become an important research direction in the field of materials science.

[0003] While existing high-temperature alloys possess certain mechanical properties and oxidation resistance at high temperatures, their resistance to electrochemical and chemical corrosion in extreme corrosive environments still needs improvement. For example, existing Inconel and Hastelloy series alloys contain more than 50% Ni, resulting in high costs. Furthermore, their high-temperature creep strength decreases significantly and their resistance to hot corrosion declines at temperatures above 650°C. Traditional stainless steels, such as 316L and S304, are prone to pitting corrosion in Cl- environments, leading to a significant reduction in high-temperature strength and making them unsuitable for extreme conditions. In addition, the complex composition design and manufacturing processes of existing alloys further limit their widespread application.

[0004] The aluminum alloy material for laser cladding disclosed in Chinese invention patent application CN119351833A contains a high proportion of rare metal elements, such as nickel 3.12-5.34%, molybdenum 4.24-6.76%, cobalt 6.54-8.12%, and various rare earth elements. Although the coating formed by it has sufficient uniformity in terms of wear resistance, high temperature resistance, and corrosion resistance, the production cost is relatively high. Chinese invention patent application CN119265458 A discloses a method for preparing a heat-resistant aluminum alloy, which is composed of the following materials in the following mass percentages: Cu 2.5-4.5%, Si 7.5-9.5%, Zn 0.5-1.0%, Mn≤0.2%, Mg 0.3-0.5%, Fe≤0.25%, Sr 0.01-0.045%, Mo 0.05-0.25%, W 0.05-0.25%, V 0.03-0.15%, with the balance being Al and impurities, wherein the total impurity content is ≤0.25%. Although the raw material cost is relatively low, the high-temperature mechanical properties can only be adapted to environments below 300℃, limiting its application scenarios.

[0005] The core problem that urgently needs to be solved in this field is how to provide an alloy system that can achieve a breakthrough in comprehensive performance through the synergistic regulation of multiple components and is cost-controllable, so as to solve the technical bottleneck that traditional materials cannot meet the requirements of high temperature and high corrosion environments. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a high-temperature and corrosion-resistant alloy material and its preparation method. Through precise composition design and process optimization, it achieves a synergistic improvement in high-temperature mechanical properties, oxidation resistance, and corrosion resistance, while significantly reducing costs compared to existing commercial high-temperature alloys. The specific details of this invention are as follows.

[0007] (1) Formulation of high-temperature and corrosion resistant high-performance alloy materials The high-temperature and corrosion-resistant alloy material has the following core components by mass percentage: The alloy composition, by mass percentage, comprises: C≤0.25%, Si≤1.50%, Mn≤2.00%, Ti 1.5-3%, Cr 22.0-25.0%, Ni 18.0-21.0%, Mo 2.5-4.5%, V 3.5-5%, P≤0.045%, S≤0.030%, with the balance being Fe and unavoidable impurities. In this invention, through alloy material composition design, the optimized alloy chemical composition, by mass percentage, mainly includes: C≤0.25%, Si≤1.50%, Mn≤2.00%, P≤0.045%, S≤0.030%, with key additions of 1.5-3% Ti, 2.5-4.5% Mo, and 3.5-5% V. Its high content of 22.0-25.0% Cr and 18.0-21.0% Ni forms the basis of the material, with the balance being Fe and unavoidable impurities. The alloy system, which achieves a breakthrough in comprehensive performance through the synergistic regulation of the above-mentioned multi-components, has excellent high-temperature mechanical properties, oxidation resistance, electrochemical corrosion resistance, and chemical corrosion resistance, making it suitable for industrial applications in high-temperature and highly corrosive environments.

[0008] Preferably, the high-temperature and corrosion-resistant alloy material, by mass percentage, comprises: C ≤ 0.20%, Si ≤ 1.30%, Mn ≤ 1.80%, Ti 1.8-2.9%, Cr 22.0-24.0%, Ni 19.0-22%, Mo 2.8-4.3%, V 3.7-4.5%, P ≤ 0.040%, S ≤ 0.025%, with the balance being Fe and unavoidable impurities. This invention, through optimized composition design of the high-temperature and corrosion-resistant alloy material, can further improve its comprehensive properties, including high-temperature mechanical properties, oxidation resistance, electrochemical corrosion resistance, and chemical corrosion resistance, making it more suitable for industrial applications in high-temperature and highly corrosive environments.

[0009] Preferably, by mass percentage, the composition is: C 0.15-0.20%, Si 1.00-1.20%, Mn 1.50-1.80%, Ti 2.0-2.8%, Cr 22.0-23.0%, Ni 19.0-20%, Mo 3.0-4.2%, V 3.8-4.5%, P ≤0.035%, S ≤0.020%, with the balance being Fe and unavoidable impurities. The optimal conditions yield the best results.

[0010] Preferably, the high-temperature and corrosion-resistant alloy material exhibits a tensile strength ≥680MPa, a yield strength ≥550MPa, an elongation ≥25% at 650℃, a creep rupture time ≥500h at 650℃ / 300MPa, and an oxidation weight gain rate ≤0.12g / (m³) at 900℃. 2 •h), the critical peeling temperature of the oxide film is ≥1050℃.

[0011] Preferably, in a 6% FeCl3 solution at 35°C, the pitting potential is ≥1.2V; in a 60% H2SO4 solution at 80°C, the corrosion rate is ≤0.08mm / a; and in a 10% NaCl solution, the electrochemical impedance modulus is ≥1×10⁻⁶. 6 Ω·cm 2 .

[0012] The high-temperature and corrosion-resistant alloy material of this invention has a performance parameter range that meets the requirements for applications in extreme environments. Its excellent performance indicators are as follows: First, high-temperature mechanical properties; at temperatures exceeding 650℃, the material must possess excellent strength and ductility, with a tensile strength of not less than 680 MPa, a yield strength of not less than 550 MPa, an elongation of not less than 25%, and a creep rupture life of over 500 hours under 650℃ / 300 MPa conditions. Second, oxidation resistance; the material must have excellent high-temperature oxidation resistance, with an oxidation weight gain rate controlled at 900℃ of 0.12 g / (m²). 2 Within a certain range (h), the critical peeling temperature of its oxide film is not lower than 1050℃. Third, corrosion resistance: in a 6% FeCl3 solution at 35℃, its pitting potential is not lower than 1.2V; in a 60% H2SO4 solution at 80℃, the annual corrosion rate is not higher than 0.08mm; simultaneously, the electrochemical impedance modulus measured in a 10% NaCl solution reaches 1×10⁻⁶. 6 Ω·cm 2 The above demonstrates excellent resistance to pitting corrosion, uniform corrosion, and chloride ion attack.

[0013] Preferably, the mass percentage of Ti, Mo and V is 1:(1.4-1.6):(2-2.8), and more preferably 1:1.5:(2-2.75). This invention optimizes the composition design of high-temperature and corrosion-resistant alloy materials, as well as the core ratio of Ti, Mo, and V, to further enhance the synergistic effect of the multi-scale phase structure and interface stability of the alloy, achieving deep coupling optimization of high-temperature mechanical properties, oxidation resistance, and corrosion resistance. Ti, as the core forming element of MC-type carbides (TiC), synergistically precipitates VC carbides with V. Within this ratio range, the carbide size can be precisely controlled to remain stable within the optimal strengthening range of 10-50 nm, and uniformly dispersed in the γ matrix, maximizing the strengthening effect of pinning dislocations and hindering grain growth, while avoiding carbide agglomeration or coarsening due to excessive amounts of a single element, ensuring a balance between the alloy's plasticity and toughness. Mo, as a key component of the Laves phase Fe2Mo, ensures that the Laves phase maintains a fine and dispersed morphology at high temperatures by matching its ratio with Ti, avoiding mechanical property degradation caused by the precipitation of coarse and brittle phases. It also provides stable support for stress bearing under high-temperature conditions, forming carbide strengthening and Laves phase strengthening with MC-type carbides. A dual high-temperature mechanical strengthening system is supported by mutual reinforcement; the synergistic ratio of V to Mo further optimizes [MoO4] under corrosive conditions. 2- With [VO3] - The improved cross-linking efficiency results in a tighter chemical bond and denser structure in the passivation film, increasing grain boundary coverage from 85% to over 90%, significantly enhancing resistance to pitting corrosion, uniform corrosion, and intergranular stress corrosion cracking. Furthermore, this design ratio promotes the synergistic growth of multilayer oxide films during high-temperature oxidation: the matched Ti content ensures a continuous repair network within the TiO2 inner layer; the synergistic ratio of Mo to Cr enhances the density and stability of the Cr2O3 outer layer; and the adhesion of the NiCr2O4 transition layer is significantly strengthened. Ultimately, this results in a stable critical peeling temperature above 1050℃ and an oxidation weight gain rate consistently below 0.12 g / (m²) at 900℃. 2 ·h), achieving simultaneous breakthroughs in the three core performance aspects.

[0014] Further preferred, the microstructure contains a γ matrix Ni-Fe-Cr, nanoscale MC-type carbides TiC and VC, and a uniformly distributed Laves phase Fe2Mo, wherein the size of the nanoscale MC-type carbides is 10-50 nm.

[0015] Further preferably, the high-temperature and corrosion-resistant alloy material forms a multi-layer oxide film under high-temperature conditions. This multi-layer oxide film preferably comprises an outer continuous Cr₂O₃ film with a thickness of 2-5 μm, an intermediate NiCr₂O₄ spinel transition layer, and an inner TiO₂ repair network. The high-temperature and corrosion-resistant alloy material also forms [MoO₄] under corrosive conditions. 2- With [VO3] - The passivation film with cross-linked structure has a grain boundary coverage of more than 85%.

[0016] According to the present invention, the core strengthening mechanism and superior performance of the high-temperature and corrosion-resistant alloy material also stem from its multi-level synergistic effect: First, multi-scale phase structure design; based on the tough γ matrix Ni-Fe-Cr, dislocations are pinned and grains are refined by precipitating 10-50 nm MC-type carbides TiC and VC, and stress is borne by the Laves phase Fe2Mo at high temperatures, thus achieving synergistic strengthening from the micro to the nano scale. Second, oxide film self-healing system; an outer continuous Cr2O3 film with a thickness of 2-5 micrometers; a transition layer of NiCr2O4 spinel structure; and an inner TiO2 selective oxidation to form a repair network. Third, corrosion protection synergy; through the interaction of various components, especially the composite effect of Mo and V, a dense [MoO4] structure is formed on the surface. 2- With [VO3] - Cross-linked passivation film; at the same time, by using grain boundary engineering design to induce Ti elements to preferentially segregate at the grain boundaries to form a high coverage protective layer, thereby synergistically and significantly improving the material's resistance to uniform corrosion and resistance to intergranular stress corrosion cracking.

[0017] (2) Preparation steps of high performance alloys The method for preparing the high-temperature resistant and corrosion-resistant alloy material provided by the present invention includes the following steps: 1) The raw materials are subjected to vacuum induction melting and electroslag remelting to obtain alloy liquid.

[0018] 2) The alloy liquid is poured to obtain the first alloy.

[0019] 3) The first alloy is subjected to solution treatment and then water quenched to obtain the second alloy.

[0020] The solution treatment temperature is 1100-1200℃, and the holding time is 1-2h.

[0021] 4) The second alloy is subjected to a stepped aging treatment. The high-performance alloy of the present invention is prepared using the above-described optimized process to ensure uniform composition, pure microstructure, and stable performance.

[0022] Preferably, in step 1), the oxygen content of the ingot is ≤15ppm; the temperature of the vacuum induction melting is 1600-1700℃, and the holding time is 1-2h. In this invention, raw materials such as pure iron, pure nickel, pure chromium, pure titanium, pure molybdenum, pure vanadium, pure silicon, pure manganese, and pure carbon are prepared according to specific composition ratios and melted using a dual process of vacuum induction melting and electroslag remelting. Preferably, melting is carried out in a vacuum induction furnace at 1600-1700℃ for 1-2h to fully alloy and remove gases; then electroslag remelting is performed to further purify the metallurgical quality.

[0023] Preferably, in step 2), the pouring temperature is 1500-1550℃. In this invention, the refined high-temperature alloy liquid is poured into a preheated mold at a pouring temperature of 1500-1550℃ to obtain an ingot with uniform composition and few defects.

[0024] Preferably, in step 4), the stepped aging treatment includes: holding at 700-800℃ for 6-8 hours, and then holding at 600-650℃ for 16-20 hours. In this invention, the material after solution treatment undergoes a stepped aging treatment, holding at 700-800℃ for 6-8 hours, followed by aging at 600-650℃ for 16-20 hours, and finally air-cooling to room temperature to achieve sufficient dispersion precipitation of the strengthening phase, promoting the fine and dispersed precipitation of MC-type carbides and Laves phase, thereby achieving strengthening.

[0025] Thirdly, the present invention provides the application of the high-temperature and corrosion-resistant alloy material or the high-temperature and corrosion-resistant alloy material obtained by the preparation method in high-temperature and high-corrosion environments; preferably, it is used in petrochemical pyrolysis furnace tubes, underground high-temperature heaters, ship propulsion systems, nuclear power high-temperature components or chemical reactors.

[0026] The high-temperature and corrosion-resistant alloy material provided by this invention reduces costs by more than 40% compared to traditional high-alloy materials, increases high-temperature strength by 20-35%, and has excellent comprehensive performance in all aspects. It has significant application advantages in extreme environments such as petrochemical cracking furnace tubes, high-performance heaters, and ship propulsion systems. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0028] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise range values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0029] Unless otherwise specified, the techniques or conditions described in the embodiments of this invention shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Devices, instruments, reagents, etc., without specified manufacturers, are all conventional products that can be purchased through legitimate channels. All experimental reagents and raw materials involved are commercially available products, and all reagents are analytical grade products.

[0030] To illustrate the composition design, preparation method, and comprehensive performance of the alloy material of the present invention, the following examples are provided and compared with comparative examples such as the commercial high-temperature alloy Inconel 625.

[0031] Example 1 This embodiment provides a high-temperature and corrosion-resistant alloy material, which is formulated with the following raw materials in weight percentages: C: 0.20%, Si: 1.20%, Mn: 1.80%, Ti: 2.0%, Cr: 25.0%, Ni: 20.5%, Mo: 3.0%, V: 4.5%, P: 0.040%, S: 0.025%, with the balance being Fe, and unavoidable impurities.

[0032] (1) Implementation steps The method for preparing the high-temperature and corrosion-resistant alloy material provided in this embodiment is carried out using the following steps.

[0033] 1) Raw material preparation: Prepare raw materials such as pure iron, pure nickel, pure chromium, pure titanium, pure molybdenum, pure vanadium, pure silicon, pure manganese, and pure carbon according to the above component ratio.

[0034] 2) Smelting: A dual process of vacuum induction melting and electroslag remelting is adopted. First, the metallurgical process is carried out in a vacuum induction furnace at 1650℃ for 1.5 hours to fully alloy and remove gases. Then, electroslag remelting is performed to further purify the metallurgical quality, controlling the oxygen content of the final melt to ≤15ppm. High-purity molten steel with oxygen content ≤15ppm and uniform composition is obtained.

[0035] 3) Casting: The refined high-temperature alloy liquid is poured into a graphite mold that has been preheated at 400℃ for 2 hours at a casting temperature of 1520℃. The casting speed is controlled at 5-8 kg / min to obtain an ingot with uniform composition, no porosity, no shrinkage cavities and inclusion defects.

[0036] 4) Rolling Treatment: After the cast ingot is cooled to room temperature in the furnace, it undergoes pre-treatment before rolling. First, the ingot is placed in a box-type resistance furnace and held at 1120℃ for 3 hours to ensure uniform internal temperature and full austenitization. Then, a hot continuous rolling process is used for multi-pass rolling, with the deformation amount controlled at 10-20% per pass, and the cumulative deformation amount at 70%. The final rolling temperature is strictly controlled to be ≥950℃. After rolling, it is cooled to room temperature by air cooling to obtain an alloy plate with a thickness of 30mm. Rolling refines the as-cast grains and eliminates casting defects, laying a good microstructure foundation for subsequent heat treatment strengthening.

[0037] 5) Heat treatment: The cast alloy is subjected to solution treatment at a temperature of 1150℃ and a holding time of 1.5h, followed by water quenching at a cooling rate of ≥50℃ / min to suppress premature precipitation of strengthening phases and obtain a uniform γ matrix structure.

[0038] 6) Aging treatment: The solution-treated material is subjected to a step-age treatment. First, it is kept at 750℃ for 8 hours, then aged at 650℃ for 16 hours, and finally air-cooled to room temperature to complete the full dispersion precipitation of the strengthening phase, promote the fine and dispersed precipitation of MC-type carbides and Laves phase, and achieve strengthening.

[0039] (2) Effect characterization The high-temperature and corrosion-resistant alloy material provided in this embodiment, after undergoing the above-described preparation process, was characterized by microstructure, tested for high-temperature oxidation performance, analyzed for corrosion passivation film, and tested for comprehensive mechanical properties. Targeted tests are shown in Table 1, and some of the tests and results are as follows: 1) Microscopic tissue characterization test Used to verify the characteristics of the γ matrix, nano-MC carbides, and Laves phase.

[0040] Test method: Macroscopic microstructure observation. Using a metallographic microscope (OM), alloy plates were sampled, ground, polished, and etched with aqua regia to observe the uniformity of the microstructure and defects.

[0041] Microscopic phase and carbide analysis. Transmission electron microscopy was used to observe the morphology, size and distribution of strengthening phases in 100 nm ultrathin sections of the rolled and heat-treated alloys, and the phase composition was analyzed by energy dispersive spectroscopy.

[0042] Qualitative verification of phase composition. X-ray diffraction (XRD) was used with a Cu target and Kα rays, scanning range 2θ = 20°-80°, step size 0.02°, to confirm the phase composition of the alloy and rule out the formation of brittle phases.

[0043] Test results: Macrostructure: OM observation shows that the alloy plate has a uniform and dense structure, free from porosity, shrinkage cavities, inclusions and grain boundary segregation defects, with an average grain size of about 60μm. The rolling process effectively eliminated casting defects.

[0044] Phase composition: The XRD pattern clearly shows the γ-Ni-Fe-Cr matrix with characteristic diffraction peaks at 2θ = 43.3°, 50.5°, and 74.3°; TiC with characteristic diffraction peaks at 2θ = 36.1° and 42.0°; VC with characteristic diffraction peaks at 2θ = 37.4° and 43.4°; and Fe2MoLaves phase with characteristic diffraction peaks at 2θ = 41.6° and 48.4°. No brittle phases such as σ or μ phases were detected.

[0045] Nanoscale carbides and Laves phase: TEM bright-field imaging shows two types of reinforcing phases uniformly dispersed on the γ-matrix. The nanoscale MC-type carbides, namely TiC and VC, are spherical or near-spherical, with sizes concentrated in the 15-40 nm range and a number density of approximately 2.5 × 10⁻⁶. 5 pcs / mm 2 There is no agglomeration; the Laves phase Fe2Mo is in the form of short rods with a size of 100-300nm, uniformly distributed along the grain interior and grain boundaries, and tightly bonded to the γ matrix interface without debonding or cracks.

[0046] This embodiment successfully achieved a multi-scale synergistic strengthening structure of γ matrix + nano-MC carbide + Laves phase through precise composition design (Ti:Mo:V = 1:1.5:2.25), hot continuous rolling process with 70% cumulative deformation, and stepped aging treatment. The rolling process refines the as-cast grains and introduces an appropriate amount of dislocations, providing more nucleation sites for TiC / VC carbides, allowing them to disperse in the matrix. By pinning dislocations and hindering grain growth, the high-temperature strength of the alloy is significantly improved, with a tensile strength of 705 MPa at 650℃. The Laves phase Fe2Mo is structurally stable at high temperatures and bears stress transmission, forming a dual effect of dispersion strengthening and high-temperature load bearing with TiC / VC, balancing strength and plasticity, with an elongation of 26% at 650℃. No brittle phases are formed, ensuring that the alloy has no risk of performance degradation during high-temperature service.

[0047] 2) High-temperature oxide film structure and performance testing Test method: High-temperature oxidation performance test. In accordance with GB / T 13303-2008 standard, the alloy sample was placed in an air environment at 900℃ for constant temperature oxidation for 100h. The mass change before and after oxidation was measured using an electronic balance, and the oxidation weight gain rate was calculated.

[0048] Oxide film critical peeling temperature test. A thermal shock test was used, in which the oxidized sample was rapidly immersed from 1050℃ into 25℃ deionized water and circulated 10 times. The peeling of the oxide film was observed by SEM. If there was no obvious peeling, the temperature was increased to 1100℃ and the test was repeated to determine the critical peeling temperature.

[0049] Oxide film structure characterization. The surface and cross-sectional morphology of the oxide film were observed using scanning electron microscopy, and the elemental distribution of each layer was analyzed using energy dispersive spectroscopy (EDS). The phase composition of the oxide film was analyzed using XRD.

[0050] Test results: Oxidation performance indicators: After oxidation at 900℃ for 100 hours, the oxidation weight gain rate is 0.09 g / (m²). 2 (·h), far below 0.12g / (m 2 •h); Thermal shock test showed that the oxide film did not peel off significantly at 1080℃, the critical peeling temperature was ≥1080℃, and it met the requirement of ≥1050℃.

[0051] Oxide film cross-sectional structure: The total thickness of the oxide film is approximately 3.2 μm, exhibiting a clear three-layer structure. The outer layer is a continuous Cr2O3 film with a thickness of 1.8 μm and a Cr element content ≥85%, which is dense and free of pores and cracks; the middle layer is a NiCr2O4 spinel transition layer with a thickness of 0.8 μm, in which Ni and Cr elements are uniformly distributed without obvious elemental segregation; the inner layer is a TiO2 repair network with a thickness of 0.6 μm, exhibiting a continuous network structure that is tightly adhered to the substrate.

[0052] Phase verification: In the XRD pattern of the oxide film, the outer diffraction peaks correspond to Cr2O3, the middle layer to NiCr2O4, and the inner layer to TiO2. The multilayer oxide film in this embodiment achieves excellent high-temperature oxidation resistance through the synergistic effects of dense protection, interface coordination, and self-healing. The outer Cr2O3 film has an extremely low oxygen diffusion coefficient of 10. -14 -10 -12 cm 2 The high-temperature oxygen content ( / s) rapidly blocks the intrusion of high-temperature oxygen into the substrate, reducing substrate oxidation loss. The lattice constant of the intermediate NiCr2O4 spinel transition layer is between that of Cr2O3 and TiO2, effectively alleviating lattice mismatch stress between the outer and inner layers, improving the overall adhesion of the oxide film, and preventing peeling during thermal shock. The inner TiO2 repair network utilizes the selective oxidation characteristics of Ti to quickly fill any micro-cracks that may occur in the outer Cr2O3 film, ensuring the integrity of the oxide film. This structure allows the alloy to maintain a significantly lower oxidation rate than commercial alloys during long-term service at 900℃, exhibiting outstanding oxide film stability and making it perfectly suited for applications such as high-temperature fluid heaters and high-temperature components in nuclear power plants.

[0053] 3) Corrosion passivation film structure and properties Test results: Pitting potential 1.35V in 6% FeCl3 solution at 35℃; corrosion rate 0.09mm / a in 60% H2SO4 solution at 80℃; electrochemical impedance modulus 1.8×10⁻⁶ in 10% NaCl solution. 6 Ω·cm 2 XPS analysis confirmed that the passivation film was [MoO4]. 2- With [VO3] - The cross-linked structure has a grain boundary coverage of 92%. Mo and V synergistically form a dense cross-linked passivation film, effectively blocking Cl. - SO4 2- Penetration; Ti element grain boundary segregation forms a protective layer to avoid grain boundary corrosion, making it suitable for highly corrosive environments such as chemical reactors and ship propulsion systems.

[0054] 4) Economic efficiency The material cost is 85 yuan / kg. By optimizing the Ni content and replacing high-cost rare metals, a significant cost reduction is achieved while maintaining high performance, giving it advantages for large-scale industrial applications.

[0055] Example 2 The method is the same as in Example 1, except that: In this embodiment, the raw materials are prepared according to the following weight percentages: C: 0.15%, Si: 1.00%, Mn: 1.50%, Ti: 2.8%, Cr: 23.0%, Ni: 19.0%, Mo: 4.2%, V: 3.8%, P: 0.035%, S: 0.020%, with the balance being Fe, and unavoidable impurities.

[0056] (1) Implementation steps The method for preparing the high-temperature and corrosion-resistant alloy material provided in this embodiment adopts the following steps: 1) Raw material preparation: Prepare pure iron, pure nickel, pure chromium, pure titanium, pure molybdenum, pure vanadium, pure silicon, pure manganese, pure carbon and other raw materials according to the above composition ratio. The purity of all raw materials is ≥99.9% to reduce the adverse effects of impurities on the performance of high Ti and Mo alloys.

[0057] 2) Smelting: A dual process of vacuum induction melting and electroslag remelting is adopted. First, the metal is smelted in a vacuum induction furnace at 1680℃ for 1 hour. The higher melting temperature promotes the full dissolution of refractory elements such as Ti and Mo, achieving composition homogenization and efficient removal of gaseous impurities. Then, electroslag remelting is carried out, using CaF2, CaO, and Al2O3 as the slag system to further reduce the content of non-metallic inclusions. The oxygen content of the final melt is strictly controlled to ≤12ppm to obtain high-purity molten steel.

[0058] 3) Casting: The refined high-temperature alloy liquid is poured into a graphite mold that has been preheated at 450℃ for 2.5 hours at a casting temperature of 1530℃. The casting speed is controlled at 6-9 kg / min to match the composition characteristics of high Ti and Mo content, avoid element segregation, and obtain an ingot with uniform composition, no porosity, no shrinkage cavities and inclusion defects.

[0059] 4) Rolling treatment: After the cast ingot is cooled to room temperature in the furnace, it undergoes pretreatment before rolling. It is held at 1130℃ for 3 hours to ensure that the high Ti and Mo content ingot is fully austenitized; then, it is rolled in multiple passes using a hot continuous rolling process, with a deformation of 12-20% per pass, a cumulative deformation of 75%, and a final rolling temperature controlled at 970℃; after rolling, it is air-cooled to room temperature to obtain an alloy plate with a thickness of 28mm. The higher cumulative deformation further refines the grains, eliminates casting defects, and provides sufficient nucleation sites for the dispersion precipitation of strengthening phases.

[0060] 5) Heat treatment: The rolled alloy sheet is solution treated at 1180℃ and held for 1 hour, followed by rapid water quenching at a cooling rate of ≥60℃ / min to fully dissolve coarse carbides, inhibit premature precipitation of strengthening phases, and obtain a uniform γ matrix structure.

[0061] 6) Aging treatment: The solution-treated material is subjected to a step-by-step aging treatment. First, it is kept at 800℃ for 6 hours to promote the initial nucleation of the Laves phase Fe2Mo; then it is kept at 600℃ for 20 hours to promote the full dispersion and precipitation of nano-sized MC-type carbides; finally, it is air-cooled to room temperature to complete the synergistic precipitation of the strengthening phase.

[0062] (2) Effect characterization The high-temperature and corrosion-resistant alloy material provided in this embodiment, after undergoing the above-described preparation process, and based on targeted testing, is shown in Table 1. Some test results and effects are explained below: 1) Microscopic tissue characterization Test results: The alloy microstructure is uniform and dense, with no obvious defects, and the average grain size is about 55 μm; XRD analysis shows that it contains a γ-Ni-Fe-Cr matrix, TiC, VC, and Fe2Mo Laves phase, and no brittle phase; TEM observation shows that the nanoscale TiC / VC carbides are concentrated in the range of 10-35 nm, with a number density of 3.2 × 10⁻⁶. 5 pcs / mm 2The Fe2Mo phase is short rod-shaped, with a size of 120-320 nm, and is uniformly dispersed. In this embodiment, Ti:Mo:V = 1:1.5:1.36. The high Ti content and extended low-temperature aging time result in finer and more numerous MC carbides, leading to a more significant dislocation pinning effect. The high Mo content and initial aging temperature of 800℃ promote the full nucleation of the Laves phase, forming a synergistic strengthening effect with the carbides, thus balancing high-temperature strength and structural stability.

[0063] 2) Structure and properties of high-temperature oxide films Test results: After oxidation at 900℃ for 100 hours, the oxidation weight gain rate was 0.11 g / (m²). 2 •h); Thermal shock tests show that the critical peeling temperature of the oxide film is ≥1100℃; The total thickness of the oxide film is approximately 3.0μm, exhibiting a three-layer structure: an outer Cr2O3 layer of 1.7μm + a NiCr2O4 transition layer of 0.7μm + an inner TiO2 layer of 0.6μm. The Cr2O3 film is dense and crack-free, while the TiO2 inner layer is intact. High Ti and Cr content, along with optimized processes, result in a lower oxygen diffusion coefficient in the outer Cr2O3 film, alleviate lattice mismatch stress in the intermediate layer, and a denser inner TiO2 repair network due to higher Ti content. This improves crack filling efficiency, enhances oxide film stability, and makes it suitable for extreme high-temperature environments.

[0064] 3) Corrosion passivation film structure and properties Test results: Pitting potential 1.28V in 6% FeCl3 solution at 35℃; corrosion rate 0.07mm / a in 60% H2SO4 solution at 80℃; electrochemical impedance modulus 2.1×10⁻⁶ in 10% NaCl solution. 6 Ω·cm 2 The grain boundary coverage reaches 95%. The high Mo content results in a passivation film porosity of <0.3%, which enhances its ability to block corrosive media; the Ti element grain boundary segregation is more significant, further reducing the risk of intergranular stress corrosion cracking.

[0065] 4) Economic efficiency The material cost is 90 yuan / kg. Although the Ti and Mo content is slightly higher, the cost advantage is still maintained by optimizing the smelting and rolling processes to reduce production losses.

[0066] Example 3 The method is the same as in Example 1, except that: In this embodiment, the raw materials are prepared according to the following weight percentages: C: 0.18%, Si: 1.10%, Mn: 1.60%, Ti: 2.4%, Cr: 22.5%, Ni: 19.5%, Mo: 3.6%, V: 5.0%, P: 0.038%, S: 0.022%, with the balance being Fe, and unavoidable impurities.

[0067] (1) Implementation steps 1) Raw material preparation: Prepare pure iron, pure nickel and other raw materials with a purity of ≥99.9% according to the above composition ratio to reduce the interference of impurities on the overall performance of the alloy.

[0068] 2) Smelting: A dual process of vacuum induction melting and electroslag remelting is adopted. The vacuum induction furnace is smelted at 1660℃ for 1.2h to promote uniform dissolution and degassing of elements. The subsequent electroslag remelting purification strictly controls the oxygen content of the melt to ≤13ppm to obtain high-purity molten steel.

[0069] 3) Casting: The refined alloy liquid is poured into a graphite mold that has been preheated at 420℃ for 2.2 hours at a casting temperature of 1525℃. The casting speed is controlled at 5.5-8.5 kg / min to avoid compositional segregation and obtain defect-free ingots.

[0070] 4) Rolling treatment: After the ingot is cooled to room temperature, it is held at 1125℃ for 3 hours to complete austenitization; hot continuous rolling is used for multiple passes, with a deformation of 11-19% per pass, a cumulative deformation of 65%, and the final rolling temperature is controlled at 965℃; after rolling, it is air-cooled to room temperature to obtain an alloy plate with a thickness of 29mm.

[0071] 5) Heat treatment: After rolling, the plate is solution treated at 1160℃, held for 1.2h and then rapidly water quenched at a cooling rate of ≥55℃ / min to obtain a uniform γ matrix.

[0072] 6) Aging treatment: After solution treatment, the material is first kept at 720℃ for 7h to promote uniform nucleation of the Laves phase; then kept at 630℃ for 18h to promote the full dispersion and precipitation of nano-MC carbides; finally, it is air-cooled to room temperature.

[0073] (2) Effect characterization Microstructure: The alloy has a dense and defect-free microstructure with an average grain size of approximately 58 μm; XRD analysis revealed the presence of a γ-Ni-Fe-Cr matrix, TiC, VC, and Fe2Mo phases, with no brittle phases; TEM observation showed that the TiC / VC carbides had a size of 12-38 nm and a number density of 2.8 × 10⁻⁶. 5 pcs / mm 2 The Fe2Mo phase has a size of 110-310 nm and is uniformly distributed.

[0074] High-temperature oxidation performance: After oxidation at 900℃ for 100 hours, the oxidation weight gain rate is 0.10 g / (m²). 2 •h); The critical peeling temperature of the oxide film is ≥1090℃, the three-layer structure is intact, the outer layer of Cr2O3 is dense, and the inner layer of TiO2 has good repairability.

[0075] Corrosion passivation film structure and properties: Pitting potential 1.32V in 6% FeCl3 solution at 35℃; corrosion rate 0.08mm / a in 60% H2SO4 solution at 80℃; electrochemical impedance modulus 1.9×10⁻⁶ in 10% NaCl solution. 6 Ω·cm 2 The cross-linked passivation film has a complete structure with a grain boundary coverage of 93%. The high V content and Mo synergistically optimize the cross-linking density of the passivation film, and the Ti element grain boundary segregation forms a stable protective layer with balanced resistance to pitting corrosion and uniform corrosion.

[0076] Economic efficiency: Material cost is 88 yuan / kg. By precisely controlling the ratio of Ti, Mo, and V to 1:1.5:2.08, excessive addition of precious elements is reduced, and the rolling process reduces the scrap rate, resulting in a significant cost advantage.

[0077] Example 4 The method is the same as in Example 1, except that: In this embodiment, the raw materials are prepared according to the following weight percentages: C: 0.17%, Si: 1.05%, Mn: 1.70%, Ti: 2.2%, Cr: 22.8%, Ni: 19.8%, Mo: 3.3%, V: 4.0%, P: 0.036%, S: 0.021%, with the balance being Fe, and unavoidable impurities.

[0078] (1) Implementation steps 1) Raw material preparation: Select various raw materials with a purity of ≥99.9% and accurately proportion them to achieve a synergistic ratio of Ti, Mo, and V of 1:1.5:1.82.

[0079] 2) Smelting: Vacuum induction melting and electroslag remelting are combined. The vacuum induction furnace is smelted at 1670℃ for 1.3 hours, which is highly efficient in degassing. After electroslag remelting, the oxygen content of the melt is ≤14ppm, the non-metallic inclusion content is extremely low, and the purity of the molten steel is high.

[0080] 3) Casting: At a casting temperature of 1535℃, the alloy liquid is poured into a graphite mold that has been preheated at 430℃ for 2.3 hours. The casting speed is 6-8.8 kg / min to obtain an ingot with uniform composition and no porosity or shrinkage cavities.

[0081] 4) Rolling treatment: After the ingot is held at 1130℃ for 3 hours to austenitize, it is hot rolled in multiple passes with a deformation of 12-18% per pass, a cumulative deformation of 72%, and a final rolling temperature of 975℃. After rolling, it is air-cooled to room temperature to obtain an alloy plate with a thickness of 28.5mm.

[0082] 5) Heat treatment: The plate is solution treated at 1170℃, held for 1.1h and then rapidly water quenched at a cooling rate of ≥58℃ / min to fully dissolve the coarse carbides and obtain a uniform γ matrix.

[0083] 6) Aging treatment: A stepped aging process of 780℃ for 6.5h + 620℃ for 19h is adopted to promote the synergistic dispersion and precipitation of Laves phase and MC carbides.

[0084] (2) Effect characterization Microstructure: The alloy has an average grain size of approximately 56 μm, and the microstructure is dense and defect-free. XRD analysis confirmed the presence of a γ-Ni-Fe-Cr matrix, TiC, VC, and Fe2Mo phases, with no brittle phases. TEM observation showed that the TiC / VC carbides have a size of 11-36 nm and a number density of 3.0 × 10⁻⁶. 5 pcs / mm 2 The Fe2Mo phase is uniformly distributed within the crystals and at the grain boundaries.

[0085] High-temperature oxidation performance: After oxidation at 900℃ for 100 hours, the oxidation weight gain rate is 0.105 g / (m²). 2 •h); The critical peeling temperature of the oxide film is ≥1095℃, and the three-layer structure of Cr2O3 outer layer 1.75μm + NiCr2O4 transition layer 0.75μm + TiO2 inner layer 0.6μm is dense and complete.

[0086] Corrosion passivation film structure and properties: Pitting potential 1.30V in 6% FeCl3 solution at 35℃; corrosion rate 0.075mm / a in 60% H2SO4 solution at 80℃; electrochemical impedance modulus 2.0×10⁻⁶ in 10% NaCl solution. 6 Ω·cm 2 [MoO4] 2- With [VO3] - The cross-linking is uniform, with a grain boundary coverage of 94%. The synergistic ratio of Ti, Mo, and V gives the passivation film both density and adhesion. Ti grain boundary segregation and the passivation film work together to provide effective protection against Cl. - erosion.

[0087] Economic efficiency: Material cost is 89 yuan / kg. By optimizing the raw material ratio and heat treatment process, and reducing element loss during production, the overall performance is close to that of Example 2, while the cost is more competitive, making it suitable for large-scale application.

[0088] Comparative Example 1 This comparative example uses the commercially available Inconel 625 alloy.

[0089] Comparative Example 2 This comparative example uses commercial alloy Haynes 230.

[0090] Comparative Example 3 This comparative example uses the same preparation method as Example 1, except that its composition is as follows: raw materials are prepared by weight percentage. C: 0.22%, Si: 1.30%, Mn: 1.70%, Ti: 1.0%, Cr: 21.0%, Ni: 17.0%, Mo: 2.2%, V: 3.0%, P: 0.042%, S: 0.028%, with the balance being Fe and unavoidable impurities.

[0091] Comparative Example 4 This comparative example uses the same component ratio as Example 1, the difference being the preparation process: melting is performed only using vacuum induction melting, omitting the electroslag remelting step; melting is carried out in a vacuum induction furnace at 1650℃ for 1.5 hours, with the oxygen content of the melt controlled at ≤30ppm. The aging treatment does not employ a stepped process, only holding at 650℃ for 24 hours, without the initial aging step at 700-800℃.

[0092] The performance of the alloys in the embodiments of the present invention was compared with that of commercial alloys Inconel 625, Haynes 230, and Comparative Examples 3 and 4. The results are shown in Table 1.

[0093] Table 1 Performance test results of the examples and comparative examples

[0094] The high-temperature and corrosion-resistant alloy material provided in this invention reduces costs by more than 40% compared to traditional high-alloy materials, increases high-temperature strength by 20-35%, and has superior overall performance. It has significant application advantages in extreme environments such as petrochemical cracking furnace tubes, high-performance heaters, and ship propulsion systems.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-temperature and corrosion-resistant alloy material, characterized in that, The composition by mass percentage includes the following components: C≤0.25%, Si≤1.50%, Mn≤2.00%, Ti 1.5-3%, Cr 22.0-25.0%, Ni 18.0-21.0%, Mo 2.5-4.5%, V 3.5-5%, P≤0.045%, S≤0.030%, with the balance being Fe and unavoidable impurities.

2. The alloy material according to claim 1, characterized in that, By mass percentage, C≤0.20%, Si≤1.30%, Mn≤1.80%, Ti 1.8-2.9%, Cr 22.0-24.0%, Ni 19.0-22%, Mo 2.8-4.3%, V 3.7-4.5%, P ≤0.040%, S ≤0.025%, with the balance being Fe and unavoidable impurities.

3. The alloy material according to claim 1 or 2, characterized in that, The mass percentages of Ti, Mo, and V are 1:(1.4-1.6):(2-2.8).

4. The alloy material according to any one of claims 1-3, characterized in that, The high-temperature and corrosion-resistant alloy material exhibits a tensile strength ≥680MPa, a yield strength ≥550MPa, an elongation ≥25% at 650℃, a creep rupture time ≥500h at 650℃ / 300MPa, and an oxidation weight gain rate ≤0.12g / (m³) at 900℃. 2 •h), the critical peeling temperature of the oxide film is ≥1050℃; Preferably, in a 6% FeCl3 solution at 35°C, the pitting potential is ≥1.2V; in a 60% H2SO4 solution at 80°C, the corrosion rate is ≤0.08mm / a; and in a 10% NaCl solution, the electrochemical impedance modulus is ≥1×10⁻⁶. 6 Ω·cm 2 .

5. The alloy material according to any one of claims 1-4, characterized in that, The microstructure contains a γ matrix Ni-Fe-Cr, nanoscale MC-type carbides TiC and VC, and uniformly distributed Laves phase Fe2Mo, wherein the size of the nanoscale MC-type carbides is 10-50 nm. Preferably, the high-temperature and corrosion-resistant alloy material forms a multi-layer oxide film under high-temperature conditions. The multi-layer oxide film preferably comprises an outer 2-5 μm thick continuous Cr2O3 film, an intermediate NiCr2O4 spinel transition layer, and an inner TiO2 repair network. The high-temperature and corrosion-resistant alloy material also forms [MoO4] under corrosive conditions. 2- With [VO3] - The passivation film with cross-linked structure has a grain boundary coverage of more than 85%.

6. A method for preparing the high-temperature resistant and corrosion-resistant alloy material according to any one of claims 1-5, characterized in that, Includes the following steps: 1) The raw materials are subjected to vacuum induction melting and electroslag remelting to obtain an alloy liquid; 2) The molten alloy is poured to obtain the first alloy; 3) The first alloy is solution treated and then quenched in water to obtain the second alloy; The solution treatment temperature is 1100-1200℃, and the holding time is 1-2 hours; 4) Perform a stepped aging treatment on the second alloy.

7. The preparation method according to claim 6, characterized in that, In step 1), the oxygen content of the ingot is ≤15ppm; the temperature of the vacuum induction melting is 1600-1700℃, and the holding time is 1-2h.

8. The preparation method according to claim 6 or 7, characterized in that, In step 2), the pouring temperature is 1500-1550℃.

9. The preparation method according to any one of claims 6-8, characterized in that, In step 4), the stepped aging treatment includes: holding at 700-800℃ for 6-8 hours, and then holding at 600-650℃ for 16-20 hours.

10. The application of the high-temperature and corrosion-resistant alloy material according to any one of claims 1-5 or the high-temperature and corrosion-resistant alloy material obtained by the preparation method according to any one of claims 6-9 in a high-temperature and high-corrosion environment; Preferably, it is used in petrochemical pyrolysis furnace tubes, underground high-temperature heaters, ship propulsion systems, nuclear power high-temperature components, or chemical reactors.

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